Bhagya

By going through these Maharashtra State Board Secretarial Practice 12th Commerce Notes Chapter 1 Introduction To Corporate Finance students can recall all the concepts quickly.

Maharashtra State Board Class 12 Secretarial Practice Notes Chapter 4 Issue of Debentures

→ The company can make a public issue of debentures only when:

• Company or its Promoters or its Directors are not prohibited from accessing securities market by SEBI.
• Company or its Promoters or its Directors have not declared themselves as defaulters or has not defaulted in repaying principal, interest or debt for a period of more than 6 months.

→ The company can issue debentures to its members through:

• Public Offer
• Private Placement

→ The company can also list its debentures on stock exchanges.

→ Section 71 of the Companies Act 2013, deals with the issue of debenture.

→ SEBI Regulation 2008 deals with provision for issue and listing of debenture which is not convertible.

→ SEBI Regulation 2009 deals with the provision for the issue of debenture and the listing of debenture that are convertible.

→ The Board of Directors has the power to issue debentures at:

• Par
• Premium
• Discount.

→ The Board of Directors can issue debentures up to a limit mentioned in the Articles of Association. Special Resolution is required to be passed in General Meeting to issue more debentures.

→ Following provisions are to be followed while issuing debentures:

• Provisions laid by Companies Act, 2013
• Provisions laid by Companies (Share Capital and Debentures) Rules 2014
• SEBI Regulation

→ Company issuing prospectus or more than 500 debentures has to appoint one or more Debenture Trustees.

→ Debenture Trust Deed is an agreed contract between the company and Debenture Trustee containing terms and conditions.

By going through these Maharashtra State Board Book Keeping & Accountancy Notes 12th Chapter 5 Reconstitution of Partnership (Death of Partner) students can recall all the concepts quickly.

Maharashtra State Board 12th Accounts Notes Chapter 5 Reconstitution of Partnership (Death of Partner)

Meaning-

Death means the permanent end of all functions of life in an organism. Accordingly when a partner dies, he no more remains as partner of a firm. On death of a partner, he ceases to be partner of a firm on natural grounds. Thus, death of a partner is equivalent to compulsory retirement. The surviving partners may continue the business if partnership firm makes provisions in partnership deed. On the death of a partner, total amount due to deceased partner is transferred to his Legal Heir’s Account or Legal Representative’s Account or Executor’s Account. Surviving partners make arrangement to make payment of deceased partner’s dues with his legal representative who is entitled to interest at 6 % p.a. on the amount due from the date of death to the date of payment. On death of a partner, profit sharing ratio of the surviving partners get increased because profit sharing ratio of deceased partner gets divided and received by surviving partners.

New Profit Sharing Ratio-

New profit sharing ratio is a ratio in which the continuing partners share the future profit or loss of the firm after the death of a partner.

Gain (Benefit) Ratio-

Profit sharing ratio which is acquired by the continuing or surviving partners on account of death of a partner is called Gain Ratio or Benefit Ratio. Gain ratio is calculated by using the following formula : Gain ratio = New ratio – Old ratio. Usually gain ratio is used by the firm to write off goodwill raised only to the extent of deceased partner’s share.

Revaluation of Assets and Liabilities-

At the time of death of a partner, all the assets and liabilities of the partnership firm are usually revalued and changes in their values are effected through a Profit and Loss Adjustment Account or Revaluation A/c. A reduction in the values of assets and an increase in the values of liabilities are debited to this Account while an increase in the values of assets and a reduction in the values of liabilities are credited to this Account. Tp transfer the deceased partner’s share in profit or loss made on revaluation of assets and liabilities, the following journal entries are passed :

(a) Transfer of profit on revaluation :

(Being share of deceased partner in revaluation profit transferred to his Capital A/c)

(b) Transfer of loss on revaluation :

(Being share of deceased partner in revaluation loss transferred to his Capital A/c)

Note : Please note that journal entries for revaluation of assets and liabilities are the same as those for admission of a partner. For pro forma journal entries and ledger accounts for revaluation of assets and liabilities, refer to Chapter 3 on Admission of a Partner in this book.

Amount due to deceased partner’s executor-

In order to ascertain the total amount payable to the deceased partner’s executor the following counting items are considered :

(1) Capital balance : Capital balance of the deceased partner shown in the last Balance Sheet is required to the transferred to Capital Account of the deceased partner on credit side as ‘By Balance b/d’.

(2) Interest op capital : If there is a provision in the partnership deed to pay interest on Partners’ Capital, the interest bmegpital for the period beginning from the date of the last Balance Sheet to the date of death of a partner is calculated at specified rate and transferred to his Capital Account by recording the following journal entries :

(3) Transfer of the deceased partner’s share in general reserve, undistributed profits and unadjusted losses : If there are any items like Reserve Fund/General Reserve/undistributed profits or unadjusted losses shown in the last Balance Sheet, then the share of the deceased partner in those items should be calculated and transferred to his Capital Account by recording the following journal entries :

(a) Transfer of general reserve and undistributed profits :

(Being share of deceased partner in general reserve and undistributed profit transferred)

(b) Transfer of unadjusted losses :

(Being share of deceased partner in unadjusted losses transferred)

(4) Share of goodwill : On the death of a partner, goodwill of the firm is to be valued as per the terms and conditions contained in the partnership agreement of the partnership firm and accordingly the share of the deceased partner can be ascertained. The share of goodwill of the deceased partner is transferred to his Capital Account by passing the following journal entry :

(Being share of deceased partner in goodwill transferred to his Capital A/c)

(5) Salary due to a deceased partner : If there is a provision in the partnership deed to pay salary to partners, salary payable for the period from last Balance Sheet to the date of death of a partner is calculated and then transferred to the deceased Partner’s Capital Account by recording the following journal entry :

(Being salary due to deceased partner transferred to his Capital A/c)

(6) Drawings of the partner : Deceased partner’s drawings for a period from the date of last Balance
Sheet till the date of his death are to be calculated and transferred to his Capital Account by recording the following journal entry :

(Being drawings of the deceased partner adjusted to his Capital A/c)

(7) Interest on Drawings : If there is a provision in the partnership deed to charge interest on partner’s drawings, the interest on drawings for the period beginning from the date of last balance sheet to the date of death is calculated at specified rate and transferred to his Capital Account by recording the following journal entry :

(Being interest due on drawings adjusted to Capital A/c)

(8) Share of the deceased partner in the accrued profits of the firm i.e. profits accrued to firm from the date of last Balance Sheet to the date of death of a partner : The accrued profit of the firm from the date of the last Balance Sheet to the date of death of a partner may be calculated either on the basis of the last year’s profit or the average of the profits for last two to five years. Deceased partner’s share for a period from the date of the last Balance Sheet to the date of death, in the accrued profit of the firm can be calculated by using the following formula :

Deceased partner’s share in accrued profit = Deceased partner’s profit sharing ratio x proportionate period for which he was in the firm during the accounting year of death x Average accrued profit of last year’s profit.
To transfer this share of profit to the Deceased Partner’s Capital A/c the following journal entry is to be passed :

(9) Share in revaluation of Assets and Liabilities :
For this, refer to Brief Overview point no. 5.4 of this Chapter.

Settlement of amount due-

After recording all the above entries, the total amount due to a deceased partner is calculated and then it is to be transferred to the Deceased Partner’s Executor’s A/c or Legal Heir’s A/c. To effect this transfer, the following journal entry is recorded in the books of the firm :

If any payment is made to Deceased Partner’s Executor/Legal Heir, then the following journal entry is passed :

The balance left in Deceased Partner’s Executor’s A/c/Legal Heir’s A/c is then treated as Deceased Partner’s Executor’s / Legal Heir’s Loan.

Accounting treatment-

Deceased Partner’s Capital Account:
In order to ascertain the amount due to a deceased partner’s executor or legal heirs or legal representative, his Capital Account is prepared. It is shown below :

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 15 Biodiversity, Conservation and Environmental Issues students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 15 Biodiversity, Conservation, and Environmental Issues

Introduction-

• Biodiversity: A variety of life that includes a vast array of species from microorganisms, viruses, algae, fungi, plants and animals present in different habitats on the earth is called biodiversity.
• Diversity is seen in shape, colour, form, mode of nutrition, habitats, reproduction, motility, duration of the life cycle, life span, etc. All of these adaptations help in the survival of species and hence diverse forms are seen.
• The term Biodiversity was coined by Walter Rosen in 1982.
• Edward Wilson popularised the term. He described it as combined diversity at different levels of biological organisation.
• Definition of biodiversity: Biodiversity is the part of nature that includes differences in the genes among individuals of a species, variety of animal and plant species in different habitats, regions, countries and the world which form different types of ecosystems within a defined area.
• Biodiversity was developed for 3.5 billion years when the evolution took place gradually.

Levels of biodiversity-

• Various levels at which diversity can be seen ranging from molecular to ecosystem levels. The three main levels, which form a hierarchy and interrelation: Genetic diversity, species diversity (community), and ecosystem diversity (Ecological diversity).
• Genetic diversity: Also called intraspecific diversity. The diversity present in the number and types of genes and chromosomes present in different species and variations in them and their alleles in the same species is called genetic diversity. Subspecies and races are also examples of genetic diversity.
• Species diversity: Also called interspecific diversity. The diversity in the number of species of plants and animals which are present in a particular region is called species diversity. Species diversity decides species richness (variety of species) and species evenness (number of individuals of different species).
• Ecological or ecosystem diversity: The diversity of different types of ecosystems and habitats
  within a given geographical area is called ecological or ecosystem diversity. E.g. Deserts, rain forests, deciduous forests, estuaries, wetlands, grasslands are different ecosystems with diverse features.

Patterns of biodiversity-

• Latitudinal and altitudinal gradient and species-area relationship are the two patterns of diversity.
• Latitudinal species diversity: There is greater species richness at a lower latitude which steadily declines towards the poles. This is called as distribution of diversity along the latitudes.
• The overall stability of tropical regions, lesser annual climatic changes, availability of plenty of sunlight, lesser drastic disturbances like periodic glaciations, lesser migrations causing reduced gene flow, normal temperature, and higher annual rainfall are all the factors that cause more diversity in these regions.
• Altitudinal species diversity: The diversity is more at lower altitudes, but at higher altitudes, it declines due to change in climatic conditions and drastic seasonal variations.
• Species area relationship: The number of species present in any area is directly proportional to the size of this area. Species richness increases with an increase in the area up to a certain limit this was observed by Alexander wan Humboldt.
• Importance of species diversity to the ecosystem: A stable community has fairly constant average biomass production over a particular time period. It withstands the disturbance and recovers quickly and also resists the invasive species.
• Productivity stability hypothesis (David Tillman): Rich diversity leads to lesser variation in the production of biomass over a particular time period.
• Rivet Popper hypothesis (Paul Ehrlich): Relationship between diversity and wellbeing of the ecosystem is not linear. When key species are lost there is a threat in a very short span of time which affects the food chain, food web, energy flow, and natural cycles resulting in an imbalance of the ecosystem.

Biodiversity current scenario-

• According to the IUCN data (2004), over 1.5 million species have been documented so far but still lot more are yet to be studied.
• Most of the temperate species have been studied but tropical species are yet to be explored.
• Robert May estimated that there are 7 million species on the earth.
• India has 8.1% of total global biodiversity. India is one of the 12 mega diversity countries. On total Indian land area which is 2.4% of the world, there are about 45000 plant species and 90000 animal varieties. 22% of global natural wealth has been recorded so far.
• But due to rapid deforestation and reclamation, many species and varieties could be lost forever before they are documented.

Loss of biodiversity-

1. Imbalance in the ecosystem occurs if biodiversity is lost. Extinction of species means a threat to biodiversity.
2. Three types of extinctions are :

• Natural extinction: Occurring due to natural causes such as forest fires, earthquakes, volcanic eruptions, etc.
• Mass extinction: Great impact causing major loss of species.
• Manmade or Anthropogenic extinction: Habitat destruction, hunting, settlement, overexploitation, reclamation are man-made causes of extinction.

3. There were five mass extinctions during different stages of the history of Earth.
4. The sixth extinction is taking place now which is a hundred to a thousand times faster than that
occurred in pre-human times.50% of diversity is said to be lost and this loss of biodiversity can alter environmental processes such as plant productivity and disease cycles.

5. Causes of biodiversity losses :
(1) Four major causes of biodiversity loss, known as an evil quartet.

• Habitat loss and fragmentation
• Overexploitation
• Alien species invasion
• Co-extinctions

(2) Extinct species: The species which are totally eliminated from the Earth.
E.g. Dinosaurs

(3) Endangered species: The species having dwindling numbers.

(4) The international union for conservation of nature and natural resources (IUCN) maintains a red data Book or red list to record the conservation status of plant and animal species.

(5) Categories of species according to IUCN:

• Extinct (EX)
• Extinct in the wild (EW)
• Critically endangered (CR)
• Endangered (EN)
• Vulnerable (VU)
• Near threatened (NT)
• Least concern (LC)
• Data deficient (DD)
• Not evaluated (NE)

Conservation and biodiversity-

1. Protection, upliftment, and scientific management of biodiversity so that it can remain at optimum level and give us sustainable benefits is called conservation of biodiversity.
2. Reasons for conservation of biodiversity :

(1) Narrowly utilitarian reasons: Humans obtain benefits from biodiversity in the form of resources for food, cloth, shelter industrial products, aesthetic products, ornaments, artifacts, and medicines.
Bioprospecting is done for systematically searching the new sources of chemical compounds, genes, microorganisms, and other valuable products that we could obtain from nature.

(2) Broadly utilitarian reasons: Oxygen supply, seed dispersal, pollination, extra aspects that nature gives us free.

(3) Ethical reasons: Humans share the earth with all the other diverse life forms and all of them have equal rights to survive. Therefore, ethically we should not finish them for our prospective economic use.

3. Conservation of biodiversity :

(1) In situ conservation :

• The protection of an organism in its natural surrounding or habitat is called in situ conservation.
• 34 biodiversity hotspots having high species richness and high density are strategically protected under in situ conservation in India.
• Traditionally used varieties for farming and horticulture are also conserved by this method.
• The Western Ghats, Indo-Burma, and Eastern Himalayas are 3 of world’s biodiversity hotspots located in India.
• In India, there Eire 14 biosphere reserves, 90 national parks, 448 wildlife sanctuaries, sacred groves are also typed of in situ conservation in which flora and fauna are protected in the name of God.
• Sacred groves are found in Khasi and Jaintia hills in Meghalaya, in Western Ghats of Maharashtra (especially Sindhudurg district), and Karnataka, Aravalli hills of Rajasthan and Bastar, Chanda and Sarguja areas in Madhya Pradesh.

(2) Ex-situ conservation :

• Critically endangered species are protected in captivity, which is called ex-situ conservation.
• An ex-situ conservation, living beings are protected in wildlife safari parks, zoological parks, botanical gardens, etc.
• Seed banks, tissue culture, cryopreservation, etc. are modern techniques that are used in this conservation method.

Biological Diversity Act 2002-

1. Earth Summit, held at Rio de Janeiro came out with the Convention on Biological Diversity (CBD-1992).
2. Indian Government has passed Biological Diversity Act (BD Act) in the year 2002 in compliance with CBD.
3. It gives framework for the sustainable management and conservation of our country’s natural resources. The law excludes value added products and human genetic material.
4. The main objectives for proposing this act are

• Regulation of access to Indian biological resources.
• Scientific cataloguing of traditional knowledge about ethnobiological materials.

5. There is three tier system in India, comprising of

• National Biodiversity Authority (NBA) at the national level
• State Biodiversity Boards (SBBs) at the state level
• Biodiversity Management Committees (BMCs) at the local level.

Environmental issues-

1. To protect and improve the quality of our environment, Indian Government has passed the Environment Protection Act in 1986.
2. Reasons for rampant loss of natural resources :

• Exponential growth of human population
• Industrial development
• Uncontrolled exploitation of nature
• Utilization and production of synthetic materials
• Construction activities
• Resultant pollution

3. Types of pollution :

• Air pollution, Noise pollution, Water pollution, Radioactive pollution, Soil pollution are different types of pollution.
• Pollutant: Substance that causes pollution is called a pollutant.

4. Air pollution :

(1) Unfavourable alteration in air quality causing damage to the respiratory system is called air pollution.
(2) Duration of exposure, concentration of pollutant and type of organism decide the severity of damage caused by air pollution.
(3) In plants, yield of crops are affected. Premature death of plants is another effect of air pollution.
(4) Major cause of air pollution is automobile traffic.

(5) Types of air pollutants : Two main types -> Particulate and Gaseous pollutants.

• Particles of less than 2.5 micrometres in diameter are extremely harmful to humans.
• Gaseous pollutants : CO, CO₂, SO₂, NO, NO₂, etc.

(6) Control measures for air pollution : For controlling emissions of gases and particulate pollutants which are released through vehicles and industries following devices are used :

• Electrostatic precipitator
• Exhaust gas scrubbers
• Catalytic converters

(7) Noise pollution :

• Noise is considered as an air pollutant which causes psychological and physiological changes in human beings.
• Sound level can damage the ear drum causing permanent hearing loss. Other problems that noise causes are sleeplessness, increased heartbeat, altered breathing, psychological stress, interference in learning etc.
• Sources of noise pollution : Machines, transportation, construction sites and industry.
• Using sound absorbing material can cause reduction in noise pollution.

5. Water pollution :

• Most of the water pollution is manmade.
• Smelling water having many pathogens, heavy metals and oils is called polluted water.
• Water Prevention and Control of Pollution Act 1974 to safeguard the water resources.
• Domestic sewage and Industrial effluents cause water pollution.
• (5) Domestic sewage contains biodegradable organic matter which can be removed by treatment.
• BOD or biochemical oxygen demand is a measure to estimate biodegradable organic matter present in the polluted water.  It is defined as the amount of dissolved oxygen required by microorganisms for decomposing the organic matter present in water which is expressed in milligram of oxygen per litre (mg/L) of water.
• Algal bloom : Excessive growth of free floating planktonic blue green algae causes algal bloom. It releases toxins in the water causing death of inhabitant fish. –
• Water hyacinth (Eichhornia crassipes) : Commonly called Terror of Bengal’ is an invasive species which grows excessively in water bodies and cause nuisance.
• Natural eutrophication : Ageing of lake over a very long period due to nutrient enrichment of water is called natural eutrophication.
• Cultural or accelerated eutrophication: Pollutants passing in the water body due to human activities cause cultural eutrophication in which there is accelerated aging process for the water body.
• Biological magnification or biomagnification : Accumulation of certain pollutant in the tissues of organisms and their increasing concentrations along the food chain is called biomagnification. E.g. DDT and mercury show biomagnification.

6. Thermal pollution : When the temperature of water is raised due to human activities, it causes thermal pollution. E.g. Effluents from thermal and nuclear power plants. Sensitive organisms are killed due to raised temperature, thus thermal pollution causes loss of flora and fauna.

7. Ecosan or Ecological sanitation :

• Use of excreta as agricultural manure in a safe and reusable manner is called ecological sanitation.
• Principle of recovery and recycling of nutrients is practised in this way.
• Ecosan is a closed system toilet which requires no water and is an alternative to leach pit toilet.
• Through such toilets composted organic manure is formed.

8. Reverse osmosis : Sewage water is reused after performing reverse osmosis.
It solves the problem of water scarcity and treatment of sewage water.

9. Rainwater harvesting : By harvesting rainwater, scarcity of water can be solved. For new constructions now it is mandatory to have provision for RWH.

10. Solid waste management :

(1) Everything that is disposed into the trash is called solid wastes.

(2) Municipal wastes : Wastes from homes, offices, stores, schools, hospitals, etc. together are called Municipal wastes. Municipality collects and disposes the same. It may contain paper, food wastes, plastics, glass, metals, rubber, leather, textile, etc.

(3) One of the ways to dispose the solid waste is to burn them. Volume of the waste is reduced by burning but burning creates air pollution.

(4) Sanitary landfills : Dumping the trash in open can attract rats and flies causing open dumps as the breeding ground for these pests. Therefore, sanitary landfills are created. At sanitary landfill sites, the wastes are compacted and buried in trenches. Everyday newer trash is added to landfills.

(5) However, this method is not a fool proof solution for the waste management as in large metro cities amount of trash is increasing day by day and hence such landfills are falling short. There is also seepage of dangerous chemicals from the sanitary landfills which results into the pollution of underground water reserves.

(6) Therefore, every human being should be sensitized towards the environmental issues. Common man should have ecological conscience to reduce the non-biodegradable trash.

(7) The solid wastes are categorized into three types :

(1) Bio-degradable
(2) Recyclable
(3) Non-biodegradable.

(8) The generated garbage should be sorted prior to disposal. The matter that could be reused or recycled should not be thrown into trash but to be given to kabadiwallahs and rag¬pickers.

(9) The biodegradable materials undergo natural breakdown. Therefore they can be buried deep down in the ground in pits.

(10) The non-biodegradable material should be reduced at source to curb the garbage generation. Packaging material, plastics, polybags, etc. which are used to a greater extent in modern times cause environmental pollution. Use of eco-friendly packaging and reduction in plastic has been advocated by the State Governments.

(11) Biomedical wastes : Hazardous wastes generated by hospitals contain disinfectants, harmful chemicals and disease-causing pathogenic microorganisms. Therefore such wastes should be carefully handled, treated and then disposed. For disposal of harmful biomedical wastes the incinerators are used.

(12) Electronic wastes (e-wastes) :

• e-wastes are any material of electronic origin, such as irreparable computers, mobile phones, CDs, floppies, batteries, etc.
• e-wastes are managed by burying them in landfills or they are incinerated.
• e-wastes generated in the developed world are exported to developing countries for further recycling and disposal.
• In China, India and Pakistan, metals like copper, iron, silicon, nickel and gold are recovered from e-wastes during recycling process.
• Developed countries, have facilities for recycling of e-wastes. But it involves manual participation and this exposes the workers to toxic substances present in e-wastes. For treating e-wastes, recycling is the only control measure. But it has to be done in an eco-friendly r manner.

11. Anti-plastic notifications : Government of Maharashtra has banned used of plastic by notification (23rd June 2018). This is a mission to make ‘Plastic Free Maharashtra’.

Greenhouse effect and Global warming-

1. Greenhouse effect :

• The greenhouse effect is the phenomenon that occurs naturally on the earth.
• The average temperature at surface of earth is increased due to greenhouse effect. If it would
  not have been there, the temperature of the earth would have been -18 °C. But due to the greenhouse now it is at the average 15 °C. This was called a good greenhouse effect.
• But in recent years the excessive greenhouse effect is causing generalized global warming and climate change.
• Infrared radiations are trapped due to atmospheric gases such as carbon dioxide, methane, etc. These gases absorb a major fraction of it and re-radiate the heat energy back to the earth’s surface. This exchange of heat goes in a cyclic manner.
• Carbon dioxide and methane are main greenhouse gases; additionally, chloroflorocarbons (CFC), Nitrous oxide (N₂O) and water vapours add to this effect.

2. Global warming :

(1) Due to air pollution and increased burning of fuels there is an increase in the proportion of greenhouse gases. The loss of forests and tree cover also adds to the increased CO₂ concentration. All this has led to global warming.
(2) In the last 100 years there is an increase in the Earth’s temperature by about 0.6 °C. Especially in last three decades the climate change is severe. Problems like El Nino effect; melting of polar ice caps, Alps and Himalayas, etc. and increasing sea level leading to coastal submergence are all due to global warming.

3. Measures to reduce greenhouse effect and Global warming : Reduction in use of fossil fuel, improving efficiency

Ozone depletion-

1. In the upper stratosphere strata there is ozone layer. It is continuously formed by action of ultraviolet radiations on molecular oxygen. Molecular oxygen also degrades back into ozone in the stratosphere. Ozone layer absorbs ultraviolet radiation from the sun and protects the flora and fauna from deleterious effects of radiation.

2. Living organisms are affected due to UV radiation because it causes damage to their DNA and proteins by breaking the chemical bonds within DNA and proteins.
3. The unit for measuring thickness of ozone is Dobson unit (DU).

4. A balance between production and degradation of ozone in the stratosphere is lately disturbed due to excessive proportion of chlorofluorocarbons (CFCs) in the atmosphere.

5. Chlorofluorocarbons are used in refrigerators. When released they move upward and reach stratosphere. The ultraviolet rays in stratosphere, react with CFC and release Cl- atoms. Ozone is degraded by Cl “atoms.

6. This later causes ozone depletion or formation of ozone hole as it is clearly seen over the Antarctic region.

7. Deleterious effects of Ozone depletion :

• Aging of skin.
• Damage to skin cells causing skin cancers.
• Inflammation of cornea of human eye causing snow-blindness cataract.
• Permanent damage to the cornea.
• UV-B radiation cause damage to DNA and mutations.

8. Montreal Protocol : An international treaty signed at Montreal (Canada) in 1987 (effective in 1989) to control the deleterious emission of ozone depleting substances like CFCs.

Deforestation –

1. Converting forested land into barren land is called deforestation.
2. Tropical forests are reduced by about 40% whereas temperate forests are lessened by 1% in the temperate region.
3. India is facing severe deforestation. There was 30% of forests in Indian land in early twentieth century. Now it has reduced to 19.4%.
4. It is recommended by National Forest Policy (1988) of India that the hilly area should have 67% while the plain area should have 33% forest cover.
5. Causes of deforestation :

• Unplanned human activities.
• Creation of agricultural land by cutting down forests.
• For the timber and firewood, trees are felled and forests are cleared.
• Clearing forests for cattle ranching.
• Slash and burn agriculture or Jhum cultivation in the north-eastern parts of India.
• Severe deforestation is caused due to increasing human population and repeated cultivation that resulted into shortening of recovery phase.

6. Consequences of deforestation :

Enhanced carbon dioxide concentration.

• Carbon held in the biomass is lost with deforestation.
• Loss of biodiversity due to habitat destruction.
• Disturbance in the hydrologic cycle.
• Soil erosion.
• Desertification.

7. Reforestation : Restoring a forest that once existed is called reforestation.
There can be a natural reforestation or it can be due to human efforts by planting trees. However, when it is due to human efforts the natural biodiversity may be lost.

8. Environmental heroes : Reforestation undertaken by these two environmentalists.

• Saalumara Thimmakka. (Karnataka)
• Moirangthem Loiya (Manipur).

9. Case study of people’s participation in conservation of forests : Following examples show people’s participation in the conservation of forests :

(1) In 1731, Amrita Devi had sacrificed her life to save trees along with other people of Bishnoi’s community. It was the example of sacrificing lives for the cause of saving trees and environment.
Amrita Devi Bishnoi Wildlife Protection Award for individuals or communities from rural areas has been installed by the Government of India.

(2) Chipko Movement is people’s participation for the protection of trees. This happened in 1974 in Garhwal region of Himalayas. Chipko movement has now spread world-wide in which people hug the trees and save it from the axe of tree-cutters.

(3) Joint Forest Management (JFM) has been introduced by the Government of India in 1980s for working with the local communities for protection and management of the forests. It is an attempt to conserve forests in a sustainable matter.

Mission Harit Maharashtra-

• Government of Maharashtra has decided to plant 50 crore trees, district-wise in 4 years, starting from in the year 2016.
• National Forest Policy (NFP) aims at maintaining 33% forest cover in India. This decision of government is in tune with NFP
• Helpline number 1926 called ‘Hello Forest’ has been set up to provide information regarding plantation, protection and for mass awareness.
• Mobile application called ‘My Plants’ to record details of the plantation such as numbers, species and location.
• Japanese Miyawaki method of plantation has been adapted in districts like, Beed, Hingoli, Pune, Jalgaon, Aurangabad, etc.

Know your conservatonist;

• Seed mother of Maharashtra, Rahibai Popere, from Ahmednagar district, runs seed bank for 54 crops and 116 varieties.
• Crops include wild varieties of brinjal, guava, mango, spinach, methi, millets, pulses, hyacinth beans and peas.
• Farmers and students are also trained by her for seed selection, enhancement of soil fertility, pest management and control.
• She is on BBC list of ‘100 women, 2018, along with 3 more Indian women.

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 1 Reproduction in Lower and Higher Plants students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 1 Reproduction in Lower and Higher Plants

Introduction – Reproduction

1. Reproduction is production of young ones like parents.
2. Essential Process related to continuity of species.
3. To maintain continuity of life, organisms produce offspring showing similar characters.
4. TWo types – Asexual reproduction and Sexual reproduction.

Asexual reproduction

1. Fusion of two compatible gametes or sex cell is not involved.
2. Production of genetically identical progeny, i. e. Clones.
3. Progeny from single organism.
4. Inheritance of genes of parent by progeny.
5. Modes of Asexual Reproduction

(1) Fragmentation

• Multicellular organism
• Small piece
• Accidental breaking E.g. Algae Spirogyra.

(2) Budding

• Unicellular organism
• One or more outgrowths, i.e. buds
• E.g. Yeast

(3) Spore formation

• Different types
• Flagellated motile zoospores
• Zoosporangia
• Biftagellate zoospores. E.g. Chlamydomonas

(4) Fission
Binary Fission E.g. Amoeba, Paramoecium

(5) Conidia formation
E.g. Fungus Penicillium

(6) Gemmule formation
E.g. Sponges

6. Vegetative reproduction :

• Asexual method
• Reproduction with vegetative plant parts.
• Artificial methods useful in agriculture and horticulture.
• New plants are identical to parent plant

7. Artificial methods-

(1) Cutting
Small piece of plant part selected.
Must possess one or more bud.

• Stem cutting
  e.g. Rose, Bougainvillea
• Leaf cutting
  e.g. Sansev feria
• Root cutting
  e.g. Blackberry

(2) Grafting

• Joining of two plant parts stock and scion
• Rooted plant — Stock
• Joined plant – Scion
• Grow together as one plant
  • Stem grafting e.g. Apple
  • Bud grafting, budding e.g. Rose

(3) Tissue Culture

• A small amount of plant tissue is carefully and aseptically grown to get plantlets.
• Micropropagation — Modern method to get plants from tissue culture. e.g. Orchids

Sexual Reproduction-

1. Involves fusion of two compatible gametes (male and female).
2. Takes place after certain maturity.
3. In higher plants, flowering indicates beginning of reproductive phase.
4. Production of genetically different offspring.
5. Variations are useful for survival and evolution of species.
6. Flowers, specialized reproductive structure producing haploid gametes-

7. Sexual reproduction – Two major events –

Meiosis-
Production of gametes (n):

• Male gametes in anther
• Female gametes in ovule

Fusion of gametes (Fertilization):

• Diploid zygote
• Embryo
• New plant-(2n) sporophyte

8. Diploid sporophyte is dominant plant body → Meiosis → Haploid spores →
gametes ← within flower ← Reduced structure ← gametophyte

9. Structure of anther – Mature anther :

• Usually dithecous (Having two lobes) → tetrasporangiate (Having four pollen sacs)
• Monothecous (Having single lobe) → Bisporangiate (Having two pollen sacs)
• When young it is homogeneous.
• Parenchymatous with epidermis.
• Heterogeneity appears with formation of archesporial cell.

10. T. S. of anther :

• Mature anther has anther wall and microsporangium.
• Anther wall is outer layer and microsporangium has sporogenous tissue.
• Anther wall has four layers, viz. Outer epidermis (Protective) followed by fibrous endothecium, thin walled middle layers and tapetum innermost nutritive layer.
• Microsporangium contains microspore mother cells (2n) which undergo meiosis to form microspore tetrad.
• Haploid (n) microspores separate from tetrad.
• When microspores develop wall around it then it is known as pollen grain.
• From archesporial cell primary parietal cell forms anther wall and sporogenous cell forms sporogenous tissue.

Microsporogenesis-

1. Process of formation of Microspores by meiosis from MMC — Microspore Mother Cell
2. Pollen grain – Non-motile with single nucleus.
Haploid
3. Pollen wall, double layered — Sporoderm

4. Pollen wall-

• Exine (outer wall)
• Intine (inner wall)

Exine (outer wall)

• Thick
• Composed of non- biodegradable sporopollenin
• Protective layer
• Smooth or variously sculptured, spiny
• Presence of thin areas germ pores for emergence of pollen tube

Intine (inner wall)

• Thin
• Cellulose and pectin
• Forms pollen tube
• Smooth

5. Pollen Viability : It is the ability of pollen grain to germinate and develop male gametophyte.

• Depends on environment factors – Temperature and humidity.
• It lasts for few minutes (Grasses, Wheat, Rice) to months (Members of Rosaceae, Solanaceae, Fabaceae, Leguminosae)

6. Development of male gametophyte :

• It is considerably reduced.
• Develops in flower.
• Pollen grain (n) is first cell of gametophyte.

7. Pollen grain-

1. First mitotic division → 2 unequal cells →

1. Vegetative cell
2. Generative cell

Vegetative cell

• Larger, Naked
• Rich in food
• Irregular nucleus

Generative cell

• Smaller, thin walled
• Dense cytoplasm
• Floats in cytoplasm of Vegetative cell

2. Second mitotic division → In generative cell → equal cells

• Two non-motile male gametes produced
• Either occur in pollen grain or in pollen tube.

3. Pollen grains are shed in either two celled stage or three celled stage.

• Pollen grains are lodged on stigma of pistil.

Structure of Anatropous ovule (Most common type)

1. Anatropous Ovule:

Ovule are preset in ovary.
Uniovulate – Mango, Wheat, Rice.
Multiovulate – Tomato, Lady’s finger

3. Parts of ovule :

• Funiculus : Stalk by which ovule is attached to placenta.
• Hilum : Point of attachment.
• Anatropous ovule : Curved ovule, where micropyle is near stalk.
• Nucellus : Parenchymatous tissue that forms body of ovule.
• Integuments : Outer and inner two protective coverings.
• Micropyle : Narrow opening at apex.
• Chalaza : Base of ovule.
• Female gametophyte or embryo sac remains embedded in nucellus.
  Oval, elongated, multicellular 7 celled structure.

Megasporogenesis-

1. Process of formation of haploid megaspores from Megaspore Mother Cell (MMC) which is diploid (2n).
2. Megaspore mother cell is situated in nucellus towards micropylar end.
3. By meiosis → Linear tetrad of 4 megaspores (n).
4. Upper 3 degenerate but lower one is functional,

• Functional megaspore – First cell of female gametophyte
• 1st mitosis -2 nuclei which migrate to opposite poles
• 2nd mitosis-2 nuclei formed at each pole
• 3rd mitosis-4 nuclei formed at each pole
• One from each pole moves towards centre – polar nuclei

5. Egg apparatus : 3 nuclei at micropylar end.
6. Central egg cell with 2 synergids.
7. Synergids with filiform apparatus – guides pollen tube towards egg.
8. Antipodal cells : 3 cells at chalazal end.
9. Definitive or secondary nucleus : 2 Polar nuclei fuse in central cell – form diploid nucleus.
10. This 7 celled 8 nucleate mature embryo sac is monosporic and endosporic, enclosed in ovule.

Pollination-

1. Pollination : Transfer of pollen grains from anther to stigma of flower.

• Pollen grains are non-motile and female gametes are produced at different site. To bring both gametes together, this is a necessary act.
• Agents of pollination also act as agent for seed dispersal.

2. Types of Pollination :
(1) Self pollination – Inbreeding

• Occurs in single flower or two flowers in same plant.
• Autogamy : Bisexual flower pollinated by its own pollen shows autogamy.
• Offspring produced by self-pollination is genetically identical to parents, e.g. Pea.

(2) Cross Pollination – Outbreeding

• Xenogamy : Two different plants are involved.
• Need pollinating agent.
• Genetically varied offspring e.g. food and fibre crops

(3) Types of cross pollination :

• Chasmogamy : When flowers open and expose their sex organs.
• Homogamy : Condition when anther and stigma mature at same time.
• Cleistogamy : Condition when flowers remain closed, e.g. Viola, Commelina.
• Geitonogamy : Conditon where transfer of pollen grains to stigma of other flower produced on same plant, e.g. Unisexual flowers of Cucurbita.

3. Agents of Pollination:

4. Comparison of different mechanisms of pollination:

Outbreeding devices – Contrivances-

1. Mechanism to prevent self-pollination and promote cross pollination.
2. Self-pollination results inbreeding depression, hence cross pollination needed.

3. Devices observed in plants.

(1) Unisexuality:

• Unisexuality flowers
• Dioecism e.g. Maize or Monoecism e.g. Papaya, Mulberry

(2) Dichogamy:

• Maturity at different times for anthers and stigma
• Protandry earlier maturity of androecium e.g. sunflower
• Ptotogyny earlier maturity of gynoecium e.g. Gloriosa

(3) Prepotency:
Rapid pollen germination on other stigma of same type e.g. Apple.

(4) Heteromorphy:

• Different forms of flowers
• Stigmas and anthers placed at different levels.
• Divided into two types
  1. Heterostyly
  2. Hcteroanthy e.g. Prtmula

(5) Herkogamy :

• Natural physical barrier between sex organs.
• Contact of pollen with stigma is avoided. eg. Calot ropis

(6) Self – sterility:

• Genetic mechanism
• Inhibits pollen germination on stigma of same flower e.g. Tobacco, Thea

Pollen-Pistil Interaction-

1. Pistil has ability to recognise right type of pollen.
2. Special proteins help in determining compatibility.
3. Physiological mechanism operates on stigmatic surface.
4. Compatible pollen absorbs water and nutrients.
5. Pollen tube emerges from germ pore and passes through style to ovule.
6. Tip of pollen tube enters synergid.
7. Growth of pollen tube is determined by specific chemicals.
8. Pollen grains can be induced to grow on artificial medium having sucrose and boric acid – in vitro tube growth.
9. Artificial hybridization :

• Crop improvement and plant breeding programmes
• Selected desired pollens are handpicked and pollinated.
• Emasculation (Removal of anthers before opening of flowers) and bagging are important steps.

Double fertilization-

1. Complex fertilization mechanism where both male gametes participate.
2. Characteristic feature of angiosperms

• Porogamy : Pollen tube entering the ovule through micropyle.
  (Most common type – enters synergid and releases its content – 2 non-motile male gametes)
• Chalazogamy : Entry of pollen tube through chalaza.
• Mesogamy : Entry of pollen tube through integuments.
• Siphonogamy : Non-motile gametes present in pollen tube.

Process of double fertilization :

Process of double fertilization in embryo sac

(1) Syngamy (Generative fertilization)

• 1 male gamete unites with egg cell, (n) + (n) =2n
• Zygote (2n)
• Embryo (Generative fertilization)

(2) Triple fusion (Vegetative fertilization)

• 1 male gamete unites with Secondary nucleus, n+(2n)=3n
• PEN – Primary Endosperm Nucleus (3n)
• Endosperm — Nutritive tissue (Vegetative fertilization)

Both male gametes are utilized in the fertilization process hence it is described as a double fertilization.

4. Significance of double fertilization :

• Unique feature of angiosperms.
• Concerned with production of seed.
• Zygote develops into embryo which in turn forms new plant.
• Triploid PEN forms endosperm – nutritive tissue for developing embryo.
• Restoration of diploid chromosome number.
• Avoids polyembryony.

Development of Endosperm-

1. Post fertilization event.
2. Developed from triploid PEN.
3. Development of embryo and endosperm is simultaneous.
4. Endosperm also regulates growth of embryo.

5. Types of endosperm:

(a) Nuclear

• Free nuclear divisions
• No wall formation
• Large central vacuole
• Wall formation at later stage
• e.g. Coconut, Wheat, Sunflower

(b) Cellular

• Divisions of PEN followed by wall formation
• e.g. Petunia
  Adoxa
  Balsam

(c) Helobial:

• First division of PEN followed by wall formation
• 2 celled unequal
• Smaller chalazal cell and larger micropylar cell
• Further free nuclear divisions

6. Mosaic Endosperm : It is variation in the endosperm having tissue of two different types, e.g. Corn – Patches of different colours giving mosaic pattern.

Development of Embryo-

1. Embryogenesis : The process of development of zygote into embryo is called Embryogenesis.
2. Zygotic embryo is situated towards micropylar end in embryo sac.
3. When some amount of endosperm is formed then only growth of embryo starts.
4. Zygote develops wall around it and becomes
oospore.
5. Oospore divided into 2 celled pro-embryo.
6. 2 celled proembryo

1. Larger Cell
2. Smaller Cell

Larger Cell

1. Towards micropyle
2. Called basal cell.
3. Suspensor initial
4. Transverse divisions to form filamentous suspensor
5. Suspensor pushes embryo
6. First swollen cell – Haustorium
7. Lowermost cell is hypophysis
8. Hypophysis forms radicle, root cap.

2. Smaller Cell:

• Towards Chalaza
• Called terminal or apical cell
• Embryonal initial
• 3 mitotic divisions
• 8 cells – octant
• Lower tier forms hypocotyl and part of radicle
• Upper tier forms plumule and Cotyledon
• Divisions to form heart shaped
• TWo lateral cotyledons
• Curvature – Horse shoe shaped

7. Embryogenesis is similar till octant stage in dicot and monocot embryo development.
8. In Monocot embryo – Single cotyledon

• Scutellum – shield shaped cotyledon
• Coleorhiza – Protective covering of radicle
• Coleoptile – Protective covering of plumule Unit

Seed and Fruit development-

1. Formation of seeds inside fruit for creating offspring for next generation.
2. Fertilization initiates seed formation.
3. Integuments form seed coat – Testa : Outer integument.
Tegmen : Inner integument.
4. Perisperm : Remnants of nucellus in seed e.g. black pepper, beet
5. Pericarp : Ovary wall becomes fruit wall
6. Seed

• Endospermic or albuminous- e.g. Castor, Maize
• Non-Endospermic or exalbuminous e.g. Bean. Pea

7. Cotyledons : Store food materials.
8. Micropyle in seed coat: For emergence of radicle.

9. Significance of Seed and Fruit Formation

• Nourishment to seed that is present inside fruit.
• Protection of seed.
• Propagating unit.
• Dispersal, spread of species.

10. Seed dormancy – Structural and physiological adaptive mechanism for survival.
11. Helpful during adverse environmental conditions.

Apomixis –

1. Phenomenon of formation of embryo through asexual methods.
2. Apogamy : Gametophytic cell produces embryo without fertilization.
3. Apospory : Sporophytic cell produces embryo without fertilization.
4. Agamospermy : Seed is produced but embryo inside is formed without meiosis and syngamy.

5. Apomixis

(A) Recurrent

• Diplospory – unreduced.
• Diploid embryo sac from megaspore mother cell.
• e.g. Taraxacum
• Apospory – apomictic embryo sac.

(B) Non-recurrent

• Parthenogenesis, Embryo formed from egg cell (n)
• Apogamy – embryo from haploid cell.
• Sterile plants.
• e.g. Nicotiana

(C) Adventive Embryony

• Addition to zygotic embryo, embryo formed from nucellus or integuments.
• e.g. Mango, Lemon, Orange.

Parthenocarpy-

1. Parthenocarpy: Fruit formation without fertilization.
2. Stimulus provided by placental tissue.
3. Chemical stimulus of auxins (IAA) responsible for enlargement of ovary.
4. No seed formation (seedless).
5. E.g. Banana, Pineapple, Papaya
6. Can be induced artificially by spraying hormones gibberellins or other physical methods.
E.g. Grapes.

Polyembryony-

1. Development of more than one embryo in the seed
2. Adventive Polyembryony : Embryo
development from nucellus or integuments.
3. Cleavage Polyembryony : Cleavage of zygote pre-embryo and the units develop into embryos.

4. Advantages :

• Genetically uniform seedlings.
• Emergence of multiple seedlings.
• Beneficial in horticulture – Growing fruits.

Learn this as well :

• Fibrous endothecium of anther wall helps in the dehiscence of anther when pollen grains are mature.
• Pollination by animals is known as zoophily. Animals like snakes, rodents, squirrel, monkeys, lemurs and elephant act as pollinating agents.
• Pollination by snails and slugs is known as malacophily.
• Pollenkitt substance in insect pollinated pollen grains is contributed by tapetum.
• In ovule, the part of the funiculus united with body of ovule, ovule wall is known as raphe. It is seen as a line or a Ridge.
• In maize grain, aleurone layer is the outer part of starchy endosperm which stores proteins.

Know your Scientist/Conservationist :

• Nawaschin : Discovery of phenomenon of double fertilization in Liliaceae family plants : Lilium and Fritillaria.
• Noll : Coined term parthenocarpy.
• Leeuwenhoek : Noticed polyembryony in Citrus seeds for first time.
• Rahibai Popare : Conservationist of Maharashtra, seed mother, created seed bank for varieties of native seed.

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 8 Respiration and Circulation students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 8 Respiration and Circulation

Respiration-

• Respiration is a biochemical process of oxidation of organic compounds in an orderly manner for the liberation of chemical energy in the form of ATP
• C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 38ATP

Organs of respiratory exchange-

1. Respiratory surface should possess the following features for efficient gaseous exchange.

• A large surface area.
• Thin, highly vascular and permeable to allow exchange of gases.
• Moist surfaces.

2. A terrestrial plant has stomata on leaves and young stems and lenticels on the stem surface for exchange of gases.

3. In animals, depending upon the complexity of organization and the surrounding medium, respiratory organs have become specialized and are usually associated with a transport system.

4. Respiratory organs In different organisms:

Human respiratory system-

Human respiratory system consists of nostrils, nasal chambers, pharynx, larynx, trachea, bronchi, bronchioles, lungs, aided by diaphragm and intercostal muscles.

1. Nostrils and nasal chambers :

(1) The nostrils are external openings of the nose. Oxygen rich air is taken into the body through the nostrils or external nares. Carbon dioxide and water vapour are released out of the body through the nostrils.

(2) The internal nares open into the pharynx. The space between the external and internal nares is known as nasal chamber. The nasal chamber is lined internally by mucous membrane and ciliated epithelium.

(3) The nasal chamber is divided into right and left parts by a cartilage called mesethmoid. Every nasal chamber is further divided into three regions, viz. vestibule, respiratory part and sensory part.

• Vestibule : The anteriormost part of the nasal chamber is vestibule. Hair present in this chamber prevent the dust particles from going inside.
• Respiratory part : It is the part which is richly supplied by capillaries. Air is made warm and moist in this region.
• Sensory part : The sensory epithelium lines this region. It is concerned with the detection of smell.

2. Pharynx :

• The pharynx is a short, vertical tube about 12 cm in length. The respiratory and food passages cross each other in the pharynx.
• The upper part of the pharynx is known as naso-pharynx. It conducts the air.
• The lower part is called laryngo-pharynx or oro-pharynx. It conducts food to the oesophagus.
• The tonsils are present in the pharynx. They are made of lymphatic tissue. They kill the bacteria that are trapped in mucus.

3. Larynx :

• The larynx produces sound. In males, it increases in size at puberty. This is termed as Adam’s apple.
• From the pharynx air enters the larynx. The opening through which it enters is called glottis.
• The glottis has a guarding flap called epiglottis.
• The epiglottis prevents the entry of food particles into the trachea.
• The vocal cords are seen along the side of the glottis. They are made of elastic tissue. They produce sound.
• Passage of air between the vocal cords and modulations created by tongue, teeth, lips and nasal cavity produce voice.

4. Trachea :

• The trachea or windpipe is about 10-12 cm long and 2.5 cm wide.
• It is situated in front of the oesophagus and runs downwards in the thorax.
• Fibrous muscular tissue supported by ‘C’ shaped cartilages form the walls of the trachea.
• 16 to 20 cartilage rings are present in the trachea.
• The trachea is lined internally by ciliated epithelium and mucous glands.
• Mucous and ciliary action remove the dust particles and push them upwards to the larynx. These particles are then gulped and taken into the oesophagus. Instant coughing can remove foreign particles that enter the trachea.

5. Bronchi and bronchioles :

• The trachea divides into two bronchi (singular- bronchus) at its distal end behind the sternum.
• The bronchus has complete ring of cartilage for support.
• The bronchi enter the lungs on either side.
• After entering the lungs each bronchus divides into secondary and tertiary bronchi. The tertiary bronchi divide further to form bronchioles.
• The bronchioles are minute and are without the cartilage rings in their walls.
• Each bronchiole ends into a bunch of alveoli which appear like a bunch of grapes. Each alveolus is balloon shaped.
• Many alveoli make the lung spongy and elastic.

6. Lungs :

• The lungs are principal respiratory organs located in the thoracic cavity.
• They are pinkish, soft, hollow, paired, elastic and distensible organs.
• The lung is enclosed in a pleural sac.
• The pleural sac has two membranes – an outer parietal and an inner visceral which enclose the pleural cavity.
• The pleural fluid which is present in the pleural cavity lubricates and prevents friction when pleural membranes slide on each other.
• The lungs are richly supplied with blood capillaries and hence are highly vascular organs.
• The left lung has two lobes while the right lung has three lobes.
• Each lobe has many bronchioles and alveolar sacs.
• The alveolar sacs are spherical and thin walled and contain about 20 alveoli.
• The alveoli are covered by a network of capillaries from pulmonary artery and pulmonary vein.
• Each alveolus has thin and elastic wall. It is about 0.1 mm in diameter.
• The alveolar wall is 0.0001 mm thick and is made of simple, non-ciliated, squamous epithelium. It has collagen and elastin fibres.
• Every lung has about 700 million alveoli which increase the surface area for the exchange of gases.
• The outermost covering of the lungs which is known as visceral pleura is made of smooth muscle fibres.
• The lobule in the lung consists of alveolar ducts, alveolar sacs and alveoli. In alveoli gaseous exchange takes place.

Mechanism of respiration –

1. The process of respiration includes breathing, external respiration, internal respiration and cellular respiration.

(A) Breathing :

• Breathing is the process by which the air comes in and goes out of the lungs.
• The rate of gaseous exchange is speeded up by breathing.
• Breathing is a part of respiration and the terms breathing and respiration are not synonymous.
• Inspiration and expiration together make breathing.

(i) Inspiration :

• Inspiration is an active process brought about by ribs, intercostal muscles, sternum and diaphragm.
• The intercostal muscles contract and pull the ribs outwards. This increases the space in the thoracic cavity. The lower part of sternum is simultaneously raised. The diaphragm contracts and flattens. This
  causes further increase in the volume of : thoracic cavity.
• Pressure in the lungs decreases and the volume | increases due to expansion of the lungs.
• Due to pressure difference the atmospheric * air rushes into the lungs through respiratory * passage as a result of which air is inspired * in.

(ii) Expiration :

• Expiration is the passive process.
• During expiration the intercostal muscles j relax and the ribs are pulled inwards.
• The diaphragm is relaxed and becomes ; dome-shaped.
• The volume of the thoracic cavity is reduced. :
• The pressure on the lungs is increased as a j result of which they get compressed.
• Air is thus expelled out of lungs through the j nares.

(iii) Respiratory cycle :

• Respiratory cycle is alternate inspiration and expiration process.
• In adult man there are 16 to 20 respiratory cycles per minute.
• The medulla oblongata in the brain controls the respiration.

(B) External respiration/exchange of gases at the alveolar level :

• Exchange of gases between the alveolar .air and the blood takes place through thin squamous epithelial layer of alveolus and similar layer of the capillary wall.
• Respiratory gases will always diffuse from an area of higher partial pressure to an area of lower partied pressure in these two regions.
• Due to difference in partial pressure, carbon dioxide diffuses from the capillaries into the alveolus whereas oxygen will diffuse from alveoli to the capillaries.
• Table : Pulmonary volumes and capacities :
  

(C) Internal respiration :

• Transport of O₂ : Only 3% of total oxygen is carried in a dissolved state by plasma while 97% of oxygen is carried in the form of oxyhaemoglobin from lungs to tissues.
• Oxygen dissociation curve : A sigmoid curve which shows oxygen-haemoglobin dissociation and the relationship between oxyhaemoglobin saturation and oxygen tension.
• Bohr effect : The shift of oxyhaemoglobin dissociation curve due to change in partial pressure of C02 in blood is called Bohr effect.
• Haldane effect : The effect caused by increase in hydrogen ions which results in decrease of pH of blood is called Haldane effect.

Transport of CO₂ :

• 7% of COa is transported in the form of carbonic acid by plasma.
• 70% of COa is transported from tissues to lungs in the form of sodium bicarbonate and potassium.
• Remaining 23% of COa is carried in the form of carbaminohaemoglobin.
• Hamburger’s phenomena or chloride shift : Movement of chloride ions to maintain the ionic balance between the RBCs and the plasma is called chloride shift.

(D) Cellular respiration : In this last step food is oxidized in the cell and ATP is produced and used to carry out vital processes.

2. Carbon monoxide poisoning :

• Haemoglobin has affinity for oxygen. But for carbon monoxide it has about 250 times more affinity than that of oxygen.
• With carbon monoxide it forms a stable compound called carboxyhaemoglobin.
• Due to such combination, the oxygen is not transported to the tissues. The tissues thus suffer from oxygen starvation. This leads to asphyxiation and in extreme cases death.
• Treatment of carbon monoxide poisoning is given by administering oxygen-carbon dioxide mixture to make high PO₂ level to dissociate the carbon monoxide from haemoglobin.
• Carbon monoxide poisoning occurs in closed rooms with open stoves, gas burners, automobile engines or any incomplete combustion.

Regulation of breathing-

• Normal breathing is an involuntary process controlled by inspiratory centres and expiratory centres in medulla, pneumotaxic centre in pons and apneustic centre located in medulla.
• The Hering-Breuer reflex controls the rate and depth of breathing and also prevents over inflation of lungs.
• Cerebral cortex has voluntary centres which prevent water or irritating gases from entering the lungs.

Modified respiratory movements-‘

Modified respiratory movements are used to express emotions and to clear air passages. They may be reflexes or voluntarily initiated movements such as yawning.

Common disorders of respiratory system-

1. Respiratory disorders:

2. Treatment of respiratory disorders is by taking suitable antibiotics, inhalants, vaporizers and cough medicines. Also quitting smoking, using preventive masks and staying away from polluted air is too remedy against these disorders.

3. Artificial ventilation : Method of induced breathing in a person who is unable to breathe is given artificial ventilation.

4. Ventilator : A machine supporting breathing when normal breathing fails.

Transportation in living organisms-
Circulation in animals-

1. Transportation by diffusion and active transport is suitable in extremely small organisms.

2. Intracellular transport by cyclosis is shown by almost all living organisms e.g. Paramoecium, Amoeba, root hair cells of many plants and WBCs in animals.

3. Extracellular transport : In this transport water or body fluid is circulated through body cavities as in sponges and coelenterates or moved around the viscera by contraction of body wall and muscles as in roundworms or parenchymal circulation, viz. flatworms.

4. Blood vascular system in higher animals from Annelida to chordate contains

• blood as a circulating fluid,
• heart as a pumping organ and
• the blood vessels through which blood circulates.

5. Types of blood vascular system :

(1) Open circulation :

• In this type, blood finally conies out of the blood vessels and is circulated through the body cavities (haemocoel).
• Blood flows at low pressure and there is direct exchange of materials between blood and cells or tissues of the body.
• Respiratory pigment is usually absent. When present, it is dissolved in plasma of the blood, e.g. Arthropods and Molluscs.

(2) Closed circulation :

• In this type of circulation, blood is circulated all over the body through the network of blood vessels.
• Blood does not come in direct contact with cells and body tissues and the exchange of materials between the blood and cell takes place through an intermediate fluid called lymph.
• Blood flows through blood vessels at high pressure and can be regulated. Respiratory pigment like haemoglobin is present for transportation of respiratory gases, e.g. All vertebrates, higher molluscs and annelids.
• Closed circulation can be of two main types : single circulation and double circulation.

(a) Single circulation : In fishes heart shows single circulation as blood passes only once through heart during one cardiac cycle.
(b) Double circulation :

• Human heart shows double circulation as blood passes twice through the heart during one cardiac cycle. The blood follows two routes, viz. pulmonary and systemic.
• Pulmonary circulation is the circulation between the heart and the lungs. The course of blood during pulmonary circulation is from the right ventricle (by pulmonary trunk) to the left atrium (by two pairs of pulmonary veins) of heart through lungs.
• Systemic circulation is the circulation between the heart and the body organs (except lungs). The course of blood during systemic circulation is from left ventricle (by systemic aorta) to all body organs and from the body back to right atrium (by vena cavae).

Learn This As Well:
Coronary circulation is circulation to the cardiac muscles of the heart. Coronary arteries supply oxygenated blood whereas coronary veins join to form coronary sinus and collect deoxygenated blood. This sinus opens into the right atrium.

Circulatory System in Human-

1. Circulatory system in human is made up of blood vascular system and lymphatic system.
2. Blood vascular system consists of blood, heart and blood vessels.
3. Blood composition and Coagulation :

• Study of blood is called haematology.
• The bright red, slightly alkaline main circulating, fluid in the human body is blood.
• Blood is a fluid connective tissue derived from mesoderm. It has pH about 7.4.
• There are about 5 litres of blood in the body which is about 8% of the total body weight.
• Composition of blood : There are two main components of blood, viz., plasma (55%) and blood corpuscles (45%).

(i) Plasma : Plasma is a straw coloured fluid part of blood, slightly alkaline, viscous fluid consisting of 90 – 92% water and 8 – 10% of solutes.

• Solutes are 7% proteins (serum albumin, serum globulin, heparin, fibrinogen and prothrombin).
• Other solutes are nutrients (glucose, amino acids, fatty acids and glycerol).
• Nitrogenous wastes such as urea, uric acid, ammonia and creatinine.
• Gases like oxygen, carbon dioxide and nitrogen.
• Regulatory substances like enzymes and hormones.
• Inorganic substances like bicarbonates, chlorides, phosphates and sulphates of sodium, potassium, calcium, magnesium, etc.

(ii) Blood corpuscles : Blood corpuscles are of three types, viz. erythrocytes (RBCs), leucocytes (WBCs) and thrombocytes (platelets).

Red blood corpuscles/erythrocytes-

• Circular, biconcave, enucleated cells of about 7 /im in diameter and 2.5 /mi in thickness.
• RBC count is about 5.1 to 5.8 million RBCs/ cu mm in male and 4.3 to 5.2 million/cu mm in female. The average life span of RBC is about 120 days.
• Erythropoiesis is formation of RBCs. It occurs in liver and spleen in foetus and in red bone marrow in adults.
• The old RBCs are destroyed in liver and spleen.
• Polycythemia is increase while erythrocytopenia is decrease in number of RBCs.
• RBCs contain respiratory pigment called haemoglobin which helps in transport of oxygen and carbon dioxide.
• The normal haemoglobin content in adult male is 14-17 gm/100 ml of blood and 13-15 gm/100 ml of blood in adult female.
• Less amount of haemoglobin leads to anaemia.
• RBCs transport oxygen from lungs to tissues and carbon dioxide from tissues to lungs. They maintain blood pH as haemoglobin acts as a buffer. They also maintain the viscosity of the blood.
• RBCs also contains an enzyme, carbonic anhydrase.
• The haematocrit is the ratio of the volume of RBCs to total blood volume of blood. Its value is different in men and women.

White blood corpuscles/Leucocytes-

• Leucocytes are colourless, nucleated, amoeboid and phagocytic cells.
• They show diapedesis, i.e. squeezing out of blood capillaries by amoeboid movement.
• The size is about 8 to 15 fxm.
• Total WBC count is 5000 to 11000 WBCs/ cu mm of blood.
• The average life span of WBCs is about 3 to 4 days.
• Leucopoiesis or formation of WBCs. It occurs in red bone marrow, spleen, lymph nodes, tonsils, thymus and Payer’s patches.
• Leucocytosis is increase while leucopenia is decrease in the number of WBCs.
• Leukaemia or blood cancer is a pathological increase in number of WBCs.
• The dead WBCs are destroyed by phagocytosis in blood, liver and lymph nodes.
• Leucocytes are of two types, viz., granulocytes and agranulocytes.
• Granulocytes are of three types, viz. neutrophils, eosinophils and basophils.
• Agranulocytes are of two types, viz. monocytes and lymphocytes.
• Characteristics of different types of leucocytes
  

Thrombocytes/Platelets-

• Thrombocytes are smallest, non-nucleated, round and biconvex. They are of about 2.5 to 5 m in diameter. Their count is about 2.5 – 4.5 lakhs/cu mm.
• Their life span is about 5 to 10 days.
• Megakaryocytes of bone marrow form thrombocytes.
• Thrombopoiesis is the formation of platelets.
• Thrombocytosis is the increase while thrombocytopenia is the decrease in platelet count.
• Thrombocytes help in coagulation of blood by releasing thromboplastin.
• Blood clotting/coagulation of blood : Active anticoagulants like heparin and antithrombin are present in the intact blood vessels. But upon the rupture of a blood vessel, bleeding starts. The fluid blood is converted into semisolid jelly by the process of blood coagulation or clotting.”

The clotting of blood is a complicated process in which many factors (12 clotting factors) present in plasma and tissues are involved.

The event that take place during blood clotting are as follows :

• Release of thromboplastin from extrinsic source in tissue and intrinsic source in plasma at injured site through a step-wise (cascade process) process.
• Formation of enzyme prothrombinase in the blood.
• Conversion of prothrombin into thrombin by prothrombinase.
• Conversion of fibrinogen into fibrin by thrombin.
• Formation of mesh by the fibrin fibres forming the clot.
• The normal clotting time is 2 to 8 minutes.

Heart-

1. Heart is a hollow, muscular, conical organ about the size of one’s fist with broad base and narrow apex tilted towards the left.
2. It is mesodermal in origin.
3. It is situated in middle of the thoracic cavity in a space called mediastinum, between the two lungs.
4. The heart is 12 cm in length, 9 cm in breadth and 250 to 300 grams in weight.
5. Pericardium : Double layered membrane, these layers are as follows :

• Fibrous pericardium : Outer, tough layer of inelastic fibrous connective tissue.
• Serous pericardium : This inner pericardium has two layers, outer parietal layer and inner visceral layer.
• Parietal layer forms the inner lining of fibrous pericardium.
• Visceral layer or epicardium is next to heart on the outer side.
• Pericardial fluid is present between the parietal and visceral layers of serous pericardium.

6. Heart wall :

• The heart wall has three layers, viz. outer epicardium, middle myocardium and inner endocardium.
• Epicardium has single layer of flat epithelial cells called mesothelium.
• Myocardium has cardiac muscle fibres responsible for movements of the heart.
• Endocardium has single layer of flat epithelial cells called endothelium.

7. External structure of heart :

• Human heart consists of two superior, small, thin walled receiving chambers called atria or auricles and two inferior, large, thick walled, distributing chambers called ventricles.
• Atrio-ventricular groove or coronary sulcus, a transverse groove which is present between the atria and the ventricles is seen externally.
• The interventricular sulcus is present between the right and left ventricles. Coronary arteries and coronary veins are present in the sulci. The coronary veins join to form coronary sinus which opens into the right atrium.
• The right atrium receives deoxygenated blood from all over the body through superior vena cava and inferior vena cava.
• Left atrium receives oxygenated blood from lungs through two pairs of pulmonary veins.
• From the right ventricle deoxygenated blood is sent to lungs through pulmonary trunk.
• From the left ventricle oxygenated blood is sent to entire body by systemic aorta.
• Ligamentum arteriosum connects the pulmonary trunk and systemic aorta. It represents ductus arteriosus of foetus.

8. Internal structure of heart :

• There are four chambers in the heart, viz., two atria and two ventricles which can be demarcated internally.
• Atria are thin walled upper receiving chambers separated from each other by interatrial septum.
• The right atrium receives deoxygenated blood from all over the body through superior vena cava, inferior vena cava and from the heart through coronary sinus.
• The opening of inferior vena cava is guarded by Eustachian valve while the opening of coronary sinus is guarded by Thebesian valve.
• The fossa ovalis is oval depression that is present on the right side of interatrial septum. It is the remnant of foramen ovale, an oval opening in the interatrial septum of the foetus.
• The left atrium receives oxygenated blood from the lungs through four openings of pulmonary veins.
• Right and left atria open into the right and left ventricles respectively through atrioventricular apertures. These are respectively guarded by tricuspid and bicuspid valves made up of connective tissue.
• The right atrioventricular valve has three flaps hence called tricuspid valve while left atrioventricular valve has two flaps hence called bicuspid valve or mitral valve.
• These valves are attached to papillary muscles of ventricles by chordae tendinae. The valves are prevented from turning back into the atria during the contraction of ventricles due to chordae tendinae.
• Ventricles are two thick walled lower, distributing chambers separated from each other by interventricular septum.
• Left ventricle has thick wall. The inner surface of the ventricle is thrown into a series of irregular muscular ridges called columnae carnae or trabeculae carnae.
• Pulmonary trunk or aorta arises from the right ventricle carrying deoxygenated blood to lungs for oxygenation. Systemic aorta arises from the left ventricle carrying oxygenated blood to all parts of the body.
• Pulmonary aorta and systemic aorta have three semilunar valves at the base which prevent the backward flow of blood during ventricular diastole.

9. Pumping action of heart : Heartbeat is the rhythmic contraction, i.e. rhythmic contraction (systole) and relaxation (diastole) of the heart. The rate of heartbeat is about 72 times per minute during which it pumps out about 5 litres of blood which equals cardiac output.

10. Conducting system of heart :

• The heartbeat in human beings originates in modified cardiac muscles called sinoatrial node (S.A. node). Therefore, the heart is said to be myogenic.
• The conducting system of heart consists of sinoatrial node (SAN), atrioventricular node (AVN), Bundle of His and Purkinje fibres.
• The heart shows auto-rhythmicity as the impulse for its rhythmic movement during beating is developed inside the heart.
• The autorhythmic fibres are developed during embryonic life. They act as pacemaker by setting the rhythm for the heart. They also form conducting system for conducting impulses throughout heart muscles.
• The impulse travels in the heart in the following manner : Sinoatrial node (Pacemaker) → Internodal pathway → Atrioventricular node → Bundle of His → Right and left bundle branches → Purkinje fibres.

Working mechanism of human heart-

1. Cardiac cycle : One atrial systole (0.1 second), one ventricular systole (0.3 second), followed by a joint diastole (0.4 second) is called a cardiac cycle. One cardiac cycle takes place in about 0.8 second and is also called a heartbeat.

(1) Atrial systole : During atrial systole, the deoxygenated blood from the right atrium enters the right ventricle through atrioventricular aperture whereas the oxygenated blood from left atrium enters the left ventricle through atrioventricular aperture. In normal conditions atrial systole lasts for 0.1 second and atrial diastole lasts for 0. 7 second.

(2) Ventricular systole : During ventricular systole, the deoxygenated blood from the right ventricle enters the pulmonary trunk and the oxygenated blood from the left ventricle enters the aorta. The backflow of blood into atria is prevented by the closure of cuspid valves of both atrioventricular apertures (lubb sound is produced) Ventricular systole lasts for 0.3 second and ventricular diastole lasts for 0.5 second.

(3) Joint diastole or complete diastole : Both atria and ventricles undergo relaxation. During ventricular diastole the backflow of blood from pulmonary trunk and systemic aorta into respective ventricles is prevented by closure of semilunar valves (dub sound is produced). The joint diastole lasts for 0.4 second.

2. Regulation of cardiac activity :

• Cardiovascular centre present in the medulla oblongata of brain regulates the working of the heart.
• Sympathetic nerves secrete adrenaline, which increases the rate of the heart.
• Parasympathetic nerves secrete acetylcholine, which decreases the rate of the heart.
• Conditions like hypoxia, acidosis, alkalosis decrease cardiac activity whereas hormones like epinephrine and nor epinephrine increase cardiac activity (chemical control).
• Elevated level of K+ and Na+ decreases cardiac activity.

Blood vessels-

1. Blood vessels are of three types, viz. arteries, veins and capillaries.

• Arteries : Blood vessels carrying blood away from the heart are called arteries. Arteries form arterioles which in turn divide and re¬divide to form capillaries.
• Veins : Blood vessels carrying blood to the heart are called veins. They have broad lumen and show low blood pressure.
• Capillaries : Capillaries are thinnest of blood vessels and formed by division and redivision of arteriole. Capillaries unite to form venules. Venules join to form veins.

2. A chart showing the differences between arteries, veins and blood capillaries :

Angiology is the study of blood vessels.

3. Heartbeat, pulse and cardiac output :

• Heartbeat is the rhythmic contraction and relaxation of the heart.
• One systole and one diastole make one heartbeat.
• Heart rate is number of beats per minute (72 times per minute).
• Stroke volume is amount of blood pumped out of the ventricles each time (About 70 ml of blood).
• Cardiac output is amount of blood pumped out of the ventricles per minute,
  i. e 72 x 70 ml = 5040 or about 5 litres of blood per minute.
• Tachycardia is faster heart rate (Over 100 beats per minute).
• Bradycardia is slower heart rate (Over 60 beats per minute).
• Pulse is a pressure wave travelling through the arteries after each ventricular systole.
• Pulse in the radial artery at the wrist is commonly measured.
• The pulse rate per minute indicates the heart rate. It is same as that of heart rate (72 per minute).
• Pulse rate changes with age, sex, posture, exercise and emotional state.

Blood pressure (B.P.)-

1. Blood pressure : Arterial blood pressure is the lateral pressure or force exerted by flowing blood on the wall of arteries.
2. Sphygmomanometer is the instrument used for measuring the blood pressure.
3. The units of blood pressure are mm Hg millimetres of mercury).
4. Blood pressure is of two types-systolic blood pressure and diastolic blood pressure.

• Systolic blood pressure : It is the maximum pressure of blood during ventricular systole. Normal systolic pressure is 120 mm Hg.
• Diastolic blood pressure : It is the minimum pressure of blood during ventricular diastole. Normal diastolic pressure is 80 mm Hg.
• The normal blood pressure is 120/80 mm Hg.
• Pulse pressure is the difference between systolic and diastolic pressure. Normal pulse pressure is 40 mm Hg.

5. Factors affecting arterial blood pressure :

• Cardiac output
• Peripheral resistance
• Blood volume
• Length and diameter of blood vessels
• Viscosity of blood
• Age
• Gender
• Venous return
• Sleep, emotions
• Exercise, anxiety

6. Hypertension :

• Hypertension means higher values of blood pressure (More than 140/90 mm Hg blood pressure values).
• Excessive high blood pressure of about 230/120 mm Hg may cause rupturing of blood vessels of eye (causing blindness), kidney (nephritis) and brain (stroke or paralysis).
• Factors such as arteriosclerosis, atherosclerosis, obesity, physical , or emotional stress, alcoholism, smoking, cholesterol rich diet, increased secretion of renin, epinephrine or aldosterone, etc. can cause blood pressure.

7. Coronary artery disease (CAD) :

• Atherosclerosis (narrowing of coronary arteries) can cause coronary artery disease.
• In CAD the heart muscle is damaged because of an inadequate amount of blood due to obstruction of its blood supply.
• Depending on the degree of obstruction symptoms may be mild chest pain (angina pectoris) or heart attack (myocardial infarction).

8. Atherosclerosis : Deposition of fatty substances in the lining of arteries, resulting in the formation of an atherosclerotic plaque. These depositions decrease the size of the arterial lumen.

9. Angina pectoris : Angina pectoris is the pain in the chest due to reduction in blood supply to cardiac muscle caused by narrowed and hardened coronary arteries.

10. Angiography : Angiography is X-ray imaging of the cardiac blood vessels to locate the position of blockages. Remedied procedures like angioplasty or bypass surgery are carried out depending upon the degree of blockage.

11. Heart Transplant : Heart transplant is replacement of severely damaged heart by normal heart from brain-dead or recently dead donor. This procedure is necessary in patients with end-stage heart failure and severe coronary arterial disease.

12. Silent heart attack : Heart attack that lacks the general symptoms of classic heart attack like extreme chest pain, hypertension, j shortness of breath, sweating and dizziness is known as silent heart attack or silent  myocardial infarction. Men are more affected J by silent heart attack than women.

Electrocardiogram-

•  Electrocardiogram or ECG is graphic record : of electrical variations produced by the heart during one heartbeat or cardiac cycle.
• Electrocardiogram or ECG machine is the instrument used to record action potentials generated by heart muscles.
• Einthoven in 1903 discovered this technique, hence he is known as the “Father of Electrocardiography”.
• A normal ECG consists of different types of waves such as P-wave, QR S-complex wave and T-wave.
• Waves of ECG and their significance :
  
• Abnormal functioning of heart such as in coronary artery diseases, heart block, angina pectoris, tachycardia, ischemic heart disease, myocardial infarction, cardiac arrest, etc. can be diagnosed by ECG.

Lymphatic system-

1. Lymph, lymphatic capillaries, lymphatic vessels and lymph nodes together constitute lymphatic system.

• Lymph is the tissue fluid that bathes the cells and is collected in lymphatic capillaries. Lymph is a fluid connective tissue just like blood but is without RBCs, platelets and some plasma proteins. It contains carbon dioxide and metabolic wastes.
• Lymphatic capillaries are thin walled vessels interwoven with the blood capillaries, present in all the tissue spaces. They are not connected with blood capillaries and are blind at one end. Lymph capillaries are wider than blood capillaries and are lined by endothelium of thin and flat cells.
• Lymphatic vessels are formed by the union of lymphatic capillaries. These are thin walled having numerous valves to prevent backflow. Thoracic or left lymphatic duct and right lymphatic duct are the main lymphatic vessels in the body.

2. Functions of lymphatic system :

• Draining off the excess tissue fluid from the extracellular spaces back into the blood.
• Transport of carbon dioxide and metabolic wastes from the tissue fluid. Transport of lymphocytes and antibodies from the lymphatic nodes to the blood.
• Transport of absorbed fats from the intestine to the blood.
• Destruction of invading microorganisms and foreign particles in the lymph nodes.

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 14 Ecosystems and Energy Flow students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 14 Ecosystems and Energy Flow

Introduction-

• Self-regulatory and self -sustaining structural and functional unit of biosphere.
• Consists of biotic and abiotic components.
• The term ecosystem was coined by Tansley.
• Ecosystems are of variable sizes from small pond to large ocean.
• Global ecosystem means entire biosphere.
• Two basic categories :
  (1) Terrestrial (forest, grassland, desert)
  (2) Aquatic (lakes, rivers, wetlands, estuaries)
• Also classified as natural ecosystem which is not based on any human inputs and artificial ecosystem which is dependent on man for constant inputs of energy or material.
• Dynamics of ecosystem : Input of ecosystem means productivity, transfer of energy in ecosystem is by a food chain, food web and nutrient cycling and output of ecosystem means degradation and energy loss.

Ecosystem-

1. Structure and function :

(1) Physical structure of ecosystem means the interaction of biotic and abiotic components in that ecosystem.

(2) Species composition of an ecosystem is understood by identification and enumeration of resident plant and animal species.

(3) Spatial pattern is the variation in ecosystem due to space. This is of two types, viz. stratification and zonation.

• Stratification : Vertical distribution of species of plants and animals at different levels. E.g. Trees, herbs, shrubs among plant species. Epipelagic, meso pelagic, bathypelagic and benthic among aquatic communities.
• Zonation : Horizontal distribution of plants and animals either on land or in water. E.g. Zonation in aquatic system : intertidal, littoral, sublittoral zones.
  Zonation in wetlands : Sub tidal channels, mudflats, Low marsh, high marsh

2. Functional aspects of ecosystem : Productivity, Decomposition, Nutrient cycling and Energy flow are the four functional aspects of any ecosystem.

(1) Productivity :

• Conversion of inorganic substances into organic material using solar energy by the autotrophs is called productivity. Consumption of autotrophs by heterotrophs.
• Solar energy is a must for any ecosystem for sustenance.
• Rate of generation of biomass in an ecosystem expressed as gram/sq. metre/ day.
• Gross primary productivity (GPP) : Rate of production of organic matter by photosynthesis.
• Net primary productivity (NPP) : Net
  Primary Productivity = Gross primary productivity – respiratory losses.
• NPP is available biomass which heterotrophs can use.
• Annual NPP of whole biosphere = 170 billion tons dry weight of organic matter. Ocean productivity = 55 billion tons.

Factors on which GPP depends :

• Resident plant species
• Availability of nutrients
• Photosynthetic capacity of plants
• Type of ecosystem

Secondary productivity : Rate of formation of new organic matter by consumers. This is available energy which is transferred to next trophic level.

(2) Decomposition :

• Breakdown of complex organic material and forming inorganic minerals from the dead matter is called decomposition.
• Detritus is raw material which is decomposed.

Factors regulating decomposition :

• Enough oxygen availability as it is an oxygen-requiring process.
• Chemical composition of detritus.
• Climatic factors.
• If detritus is rich in lignin and chitin the rate of decomposition rate is slower. If the detritus is rich in nitrogen and sugars the rate is faster.
• Most important factors for decomposition are temperature and soil moisture. These factors affect activities of soil microbes. In warm and moist environment decomposition is faster whereas in low temperature and in absence of oxygen, the decomposition is inhibited.

(3) Nutrient cycling : Storage and transport of nutrients.

(4) Energy flow : Flow of energy from producer to consumer in unidirectional way. Dissipation and loss of heat during energy flow is inevitable.

Energy flow –

1. The ultimate source of energy for all the globed ecosystems is sun. However, in deep sea hydrothermal ecosystem solar energy does not reach.
2.  Less than 50% of solar radiation that falls on the earth’s surface is photosynthetically active radiation (PAR). Only 2-10 % of PAR sustains the entire living world.
3. Plants and autotrophic bacteria fix solar radiant energy into complex carbohydrates while using simple inorganic materials. Plants thus are the producers that supply the energy in the form of food to consumers.
4. There is always unidirectional flow of energy ; from the sun to autotrophic producers and : then to heterotrophic consumers.
5. Second Law of thermodynamics operates for the ecosystems too. The universal tendency towards increasing disorderliness is always counteracted by producers and consumers.
6. Organisms in the ecosystem need a constant : supply of energy to survive and synthesise the : required molecules.
7. Major primary producers are herbaceous and woody plants in a terrestrial ecosystem. In an aquatic ecosystem primary producers are phytoplankton and algae.
8. Food chain/Food web : The chain or web formed due to interdependency among various organisms of the ecosystem is known as food chain.
9. Energy that is trapped into an organism keeps on flowing. Producers trap the energy and pass it further to a consumer. If the producer dies, the death of organism starts the detritus food chain/web.
10. All animals directly or indirectly depend on : plants to obtain their food. They cannot synthesise their own food so they are called ; heterotrophs or consumers.
11. Primary consumers : Consumers feeding directly on the producers are called primary consumers. For example, Herbivorous animals. Insects, birds and some mammals are herbivores or primary consumers in the terrestrial ecosystem and molluscs are primary consumers in aquatic ecosystem.
12. Secondary consumers : The animals consuming other animals are secondary consumers. For example, Carnivores. Primary carnivores are secondary consumers. Secondary consumers feed on primary consumers.
13. Tertiary consumers : Animals feeding on secondary consumers are called tertiary consumers.
    For example, in the food chain “Plant matter → Insect → Frog → Snake”, insect is primary consumer, frog is secondary consumer and snake is the tertiary consumer.
14. Food chains are of two types : Grazing food chain and detritus food chain.

(1) A simple grazing food chain (GFC) is shown as follows :

(2) The detritus food chain (DFC) is made up of decomposers. It starts with dead and decaying matter. Examples of decomposers are fungi and bacteria. Decomposers are also called heterotrophic saprotrophs. (sapro : to decompose). By degrading dead organic matter or detritus, decomposers meet their nutritional and energy requirements. Digestive enzymes of saprotrophs breakdown dead and waste materials into simple inorganic materials before their absorption which are subsequently absorbed by them.

(3) In an aquatic ecosystem energy flow occurs only through grazing food chains whereas in a terrestrial ecosystem, majority of energy flow occurs through the detritus food chain.

(4) There are interconnections between detritus i food chain and grazing food chain at some levels. Some organisms of DFC serve as prey & to the GFC animals. Some animals like cockroaches, crows, pig and mam, etc. are omnivores.

(5) The natural interconnection of food chains is called a food web.

15. Diagrammatic representations of trophic levels in an ecosystem

• At each successive trophic level, the amount of energy available goes on reducing. The trophic levels in any food chain transfer the energy when it is functioned.
• ‘10% Law’ of R. Lindermann, 1942 : The law states that ‘only 10% of the energy is transferred to each trophic level as net energy, from the previous trophic level’.
• Food chains are never in isolation, but are always interconnected to form food web for maintaining the stability of an ecosystem.

Ecological Pyramids-

1. Ecological pyramid is the expression drawn to indicate number, biomass or energy in an ecosystem.

2. The broad base and narrow apex of a pyramid rightly expresses the food or energy relationship within different trophic level. The producers or the first trophic level is shown as a base of each pyramid while the apex represents tertiary or top level consumer.

3. The three types of ecological pyramids are :

• Pyramid of number
• Pyramid of biomass and
• Pyramid of energy.

4. The calculations of energy content, biomass, or number include all organisms at that trophic level. Some organisms may occupy more than one trophic level simultaneously, e.g. A primary consumer sparrow can become secondary consumer when it feeds on insects. The trophic level thus represents a functional level and not a species as such.

5. All the pyramids, of number, of energy and biomass are upright in most of the ecosystems, i.e., producers always outnumber the consumers. Similarly biomass is more for producers than that of the herbivores. Herbivores or primary consumers outnumber carnivores. Energy at a higher trophic level is always less than energy at the lower trophic level.

6. Exceptions to pyramid structure :

• The pyramid of biomass in sea is also generally inverted as the biomass of fishes far exceeds that of phytoplankton.
• Many insects and birds thriving on a single huge tree will also show inverted pyramid of numbers.

7. When energy flows from a lower trophic level to the next trophic level, some energy is always lost as heat at each step. Therefore the pyramid of energy is always upright. It is never inverted. In the energy pyramid, the amount of energy in a given time and per unit area is shown by each bar.

8. Limitations of the ecological pyramids :

• Ecological pyramids do not take into account the same species belonging to two or more trophic levels.
• They are based on simple food chain. In nature simple food chains do not exist but all the trophic relationships are in the form of food web.
• Saprophytes play a major and vital role in the ecosystem but they are not shown in ecological pyramids.

9. C. Elton in 1927 developed the concept of ecological pyramids.

Nutrient cycles-

1. Nutrient cycling : Nutrient cycling or biogeochemical cycle is the movement of nutrient elements through various components of ecosystem.
2. Two types of nutrient cycles :

• Gaseous (nitrogen, oxygen and carbon) having reservoir in atmosphere.
• Sedimentary (Phosphorus, Sulphur) having Earth’s crust as reservoir.

3. Carbon Cycle : (Gaseous cycle)

• Five basic processes running the carbon cycle : Photos ynthesis, respiration, decomposition, sedimentation and combustion.
• Main component of all organic compounds in protoplasm is carbon.
• 49% of dry weight of organisms is carbon.
• Out of total global carbon, 71% carbon is present in oceans.
• Atmospheric Carbon dioxide regulation is done by oceanic reservoir.
• Long term storage places or sinks : Carbon which is a part of rocks and fossil fuels is called long tern storage of carbon.
• The fossil fuels from this sink when burnt, releases carbon dioxide into atmosphere.
• Elemental carbon found in seawater, atmosphere, – limestone, coal, soil and in living beings.
• Moment of carbon dioxide from atmosphere to plants is through photosynthesis.
• Carbon dioxide given out through plants and animals during respiration.
• Carbon also moves along the food chains.
• Carbon dioxide is released into atmosphere by decomposers during decomposition! process of organic matter on land and in oceans.
• Burning of fossil fuels in industries and for vehicular traffic releases carbon dioxide.
• 5.5 billion tonnes of carbon released in atmosphere, of these 3.3 billion tonnes stay in atmosphere and rest dissolves in seawater and gets deposited as calcium or magnesium carbonate compounds used for forming marine animals’ shells.
• Forest fires, volcanic activities are other natural sources releasing carbon dioxide.
• Anthropogenic activities such as deforestation and excessive burning of fossil fuel has tremendously increased amount of carbon dioxide in atmosphere.

4. Phosphorus cycle : (Sedimentary cycle)

• Phosphorus cyclically moves through hydrosphere, lithosphere and biosphere.
• It is a major constituent of biological
  membranes, nucleic acids and cellular energy transfer systems. .
• Animals require large quantities of phosphorus to make shells, bones, hooves and teeth.
• The natural reservoirs are rocks containing phosphates.
• Weathering of rocks release minute amounts of phosphates in soil solution which is needed by plants.
• Herbivores and other animals get phosphorus through plants.
• Decomposition of waste products and the dead organisms by phosphate-solubilizing bacteria release phosphorus.
• Phosphorus is always in short supply, thus acts as a limiting factor for the plant growth.
• Eutrophication : Eutrophication is the sudden influx of phosphorus in water bodies due to agricultural runoff or industrial effluents which are rich in phosphate content.
• Eutrophication causes overgrowth of algae which kills or harms the aquatic life

Ecological succession-

1. Ecological succession : The gradual and fairly predictable change in the species composition of a given area is called ecological succession. It is a community response to the environment over time.

2. All communities constantly change their composition and structure in accordance with the changing environmental conditions. This change is orderly and sequential, parallel with the changes in the physical environment.

3. Climax community : Community that is in near equilibrium with the environment after the ecological succession.
The change is sequential and environmentally regulated in climax community.

4. Process of succession involves following sequential steps :

• Nudation
• Invasion
• Ecesis
• Aggregation
• Competition and co-action
• Reaction and stabilization.

Learn This As Well :
1916, Frederic Clements published a descriptive theory of succession which is called classical ecological theory. His theory of succession had a powerful influence on ecological thought. He has given following phases of succession :

• Nudation : Nudation is disturbance. Succession begins with the development of a bare site.
• Migration : The tiny seeds or propagules arrive during this phase.
• Ecesis : Ecesis is the establishment and initial growth of vegetation.
• Competition : When vegetation becomes well-formed and established, it grows and competes with other species for space, light and nutrients.
• Reaction : Autogenic changes such as the build-up of humus affect the habitat, and one plant community replaces another during this phase.
• Stabilization : The community which is better, becomes stable forming a Climax community.

5. Some populations become more numerous, whereas some populations decline and even disappear during the succession. Newer species also colonise the areas.

6. Sere : Sere is the entire sequence of communities that successively change in a given area. Serai stages or serai communities are the individual transitional communities in this sere.

7. Following changes take place in the successive serai stages :

• Change in the diversity of species of organisms,
• Increase in the number of species and organisms,
• Increase in the total biomass.

8. Similar succession is said to have taken place in past over millions of years forming the present day global communities. Succession and evolution were the parallel processes in the past and also at the present.

9. Succession is of two types, viz. Primary succession and secondary succession.

Primary succession : It is the process that starts where no living organisms are there, e.g. bare rock, newly cooled lava, newly created pond or reservoir. The primary succession is very slow process of establishment of a new biotic community. Factors such as soil, climatic conditions, etc. The natural processes that take place for thousands of years till the new community is established.

Secondary succession : It occurs in areas where all life forms were lost that existed before. It begins in places like abandoned farmlands, burned or cut forests, lands that have been flooded, etc. Secondary succession is faster as some abiotic factors such as soil or sediment are already present there.

10. Ecological succession usually focuses on changes in vegetation. But when the vegetation changes, it in turn affects various types of animals as animals are dependent on plants for their food and shelter.

11. Therefore, with process of succession the numbers and types of animals and decomposers also show change.

12. Natural or human induced disturbances (fire, deforestation, etc.), in a normal succession pattern can convert a particular serai stage of succession to an earlier stage or create new conditions that encourage some species and eliminate other species.

13. Succession of Plants :

• Succession of plants can be of hydrarch (in wet areas) or xerarch (in very dry areas) based on the nature of the habitat.
• In hydrarch succession, successional series progress from hydric to the mesic conditions.
• In xerarch succession, successional series progress from xeric to mesic conditions.
• Both hydrarch and xerarch successions lead to mesic (medium water) conditions but neither too xeric nor too hydric.

14. Pioneer species : The species that initially invade a barren area is called pioneer species.

Ecosystem Services-

1. Ecosystem services: Ecosystem services are the products of ecosystem and processes which comprise of economic, environmental, aesthetic goods and services.
2. Millennium ecosystem assessment report 2005 as given definition of ecosystem services as follows ecosystem services is dcfincd as benefits which are obtained by people from ecosystem.
3. There are four types of ecosystem services:

4. Main important ecological services on earth without which life would not have been possible:

• FIxation of atmospheric CO₂ and release of O₂, by photosynthesis and intake of oxygen and release
  of CO₂ in respiration.
• Pollination of plants brought about by wind, water or other blotic agencies.
• MaintaIning biodiversity.

By going through these Maharashtra State Board Organisation of Commerce and Management 12th Notes Chapter 5 Emerging Modes of Business students can recall all the concepts quickly.

Maharashtra State Board Organisation of Commerce and Management 12th Notes Chapter 5 Emerging Modes of Business

→ Policy: Definite course of action followed by a business firm, government, etc. to achieve its objectives.

→ Negotiate: To deal or bargain with others as in working out the terms of a contract.

→ Registration: A process of entering the name and other relevant details like e-mail id, card details, etc. with the internet.

→ Repository: A container or place where things are deposited or stored.

→ Infrastructure: The basic facilities like roads, electricity, water, etc., that are required for the smooth running of a business, factory, etc., in particular and economy in general.

→ Marketing: The activities of a business enterprise that are connected with acquiring, maintaining and expanding markets for its products and for ensuring that its product reaches the consumers in time.

→ Recruitment: The process of searching the prospective and capable employees and encouraging them to apply for jobs in the organisation. It aims at attracting potential employees to the organisation to create a large pool for better selection.

→ Hacker: A person who is excellent at computer programming and uses computer systems illegally for private gain.

→ Off shore: Company makes contract with the foreign company in respect of outsourcing services.

→ Onshore: Company makes contract with another company of home country in respect of outsourcing services.

→ Near shore: Company makes contract with a company of neighbouring country in respect of outsourcing services.

E-Business-

Introduction: E-business is an abbreviation of electronic business. In 1997, the term e-business was first used by International Business Machines (IBM). Before that the term e-commerce was in use. E-business implies use of internet to connect people and process. International trade for goods and services started growing rapidly due to use of internet. In brief, e-business, means the use of Web, internet, intranet, extranets or some combination thereof to conduct business. E-business helps to open new door to the customers, brings closer and builds responsive relationship with partners, employees, suppliers, etc., makes new inventions and innovative ways to . add value to existing products, e-business with the help of internet and web support provide opportunities in different areas such as selling, customer relationship, product/service design, geographic expansion, etc. e-business is nothing but business on internet.

Meaning:
The electronic business i.e. e-business is originated from the two terms e-mail and e-commerce. Thus electronic business commonly referred to as ‘e-business’ or ‘an internet business’ may be defined as the application or utilisation of information and communication technologies (ICT) in support of all business activities, e-business involves purchasing and selling on internet processing orders electronically, making online payments via credit cards or debit cards, direct fund transfer handling customer services and co-operating with business partners using with technical or customer support. The term e-commerce and e-business are different. In fact, e-business includes e-commerce.

Scope of e-business:
The scope of e-business is extended to online shopping, online stock, online transactions, e-commerce and use of software. Most of the business are now aware of the advantages of e-business and are now started incorporating e-business in their policies and strategies. It facilitates direct and better communication between the consumers and business houses and makes purchasing easier for large organisations.

The scope of e-business becoming vast because almost all kinds of business functions such as production, finance, marketing, personnel administration, management functions like planning, organising, co-ordinating, controlling etc. are now carried out via computer networks. The different business and payment apps such as Phone Pay. Google Pay, Swiggy, Ola, etc. are used in e-business transactions. The various types of e-business transactions are:

Types of E-business transaction-

1. Business to Business (B2B)
2. Business to Consumer (B2C)
3. Consumer to Business (C2B)
4. Consumer to Consumer (C2C)
5. Business to Administration (B2A)
6. Consumer to Administration (C2A)

1) Business to Business (B2B): Under B2B, one business firm communicates and interacts with other business firms for different varieties and ranges of services. Example is value added services like catering and also providing manpower. It does not involve individuals.

2) Business to Consumer (B2C): Under B2C, business firms sell goods and services to the consumers. Firms use their website for various marketing activities like promotion, information, review, etc. Examples are www.flipkart.com, www.yebhi.com, etc.

3) Consumer to Business (C2B): Under C2B, the consumer posts his request with a set budget online, quote price for specific service or goods to the business. The companies review the
customers’ requirement and finalise the order. For instance, pest control service, door step food delivery, taxi services, etc.

4) Consumer to Consumer (C2C): The transactions such as buying and selling of variety of goods under C2C are between consumer and other consumers. Internet offers lot of scope for this activity. Payment modes for transactions are secured through advanced technology. The website do the job of intermediaries i.e. to match the consumers. Example of such a website is eBay.

5) Business to Administration (B2A): All transactions conducted online between business and public administration come under B2A, e.g. registration of companies, payment of taxes, obtaining various types of licences and permits, etc.

6) Consumer to Administration (C2A): All transactions conducted online between consumers (individuals) and public administration are j included in C2A. e.g. getting passport, aadhaar card, Pan card, licences, etc.

Benefits of E-business-

Internet has become fourth channel for trade. It has many advantages:

• Ease of formation: As compared to traditional business, e-business is relatively easy 5 to start and operate.
• Lower investment requirements: Investment requirements of e-business is very low in comparison to traditional business. It does not require large store and large manpower to conduct business. More contacts and effective communication can do huge business.
• Convenience: E-business of any thing can be done anytime and anywhere. It offers j convenience of 24 x 7 x 365 days a year.
• Speed: All aspects of business transactions such as buying or selling, making payments, etc. j can be done quickly and speedily at the click of mouse.
• Global access: Internet is boundryless. It allows the seller to have access to global market and also offers freedom to the buyer to choose products from any part of the world. For e-business face to face interaction between buyer and seller is not required.
• Movement towards a paperless society: Use of internet has reduced the dependence on paperwork to great extent. Recording and referencing of information has become easy.
• Government support: Government favours and supports e-business. It ensures maximum transparency.
• Easy payment: In e-business transactions, the payment is done by fund transfer, credit card, etc. Such payment can be made anytime, quickly and round the clock.

Limitations of e-business-

• Lack of personal touch: Lack of physical inspection and personal touch affect its sale adversely. The consumer cannot check the quality of product.
• Delivery time: In e-business, delivery of products is considerably delayed in comparison to traditional business. Time lag always discourages consumers to buy products online.
• Security issues: Scam and cheating through online business by the people or hackers cannot be denied. It lacks adequate security and integrity. It also disturbs the entry of potential buyers.
• Government interference: Government interference sometimes puts hurdles on its growth and expansion.
• High risk: E-business involves high risk because of absence of direct contact between the buyer and seller. In case of fraud, it is difficult to take legal action against the wrongdoer.

Online Transaction-

Meaning: Business transactions which are carried out and completed between seller and buyer with the help of internet are called online business transactions. In this, placing an order, selection of goods, execution of order, transfer of funds, etc. are completed via internet by using websites and e-mail addresses of buyer and seller.

Procedure of online Transaction: In online transaction, there are three stages, viz. pre-purchase/sale stage, actual purchase/sale stage and delivery stage.

Online transaction involves the following steps:

1) Registration: Registration is required for online transactions. One who wants to do online shopping is required to login on a website and fill relevant details with the online vendor. The customer’s email id, name, address and other details are saved by the website for future use.

2) Placing an order: The online customer or shopper can select, pick up and drop the items or things in the shopping cart. The shopping cart keeps the systematic and detail record of what items or things have been picked up and dropped in the shopping cart and the price of each. The buyer then needs to make payment.

3) Payments: The payment system, is fully secured. Payment can be made in one of the following ways:

• Cash on Delivery (COD): According to this mode of payment, after receiving physical delivery of goods at the door step, payments for the online goods ordered is effected by cash payment or by debit or credit card.
• Cheque: Under this mode of payment, the vendor collects the cheque from the customer and after realisation of the cheque, delivery of the goods is given to the buyer.
• Net banking transfer: Under this mode, the payment is made by buyer to vendor by transfer of funds through the internet. The buyer transfers the agreed purchase amount to the online vendor’s account. After receiving the amount, the vendor delivers the goods to the buyer.
• Credit or Debit Cards: The credit card or debit card is used by the cardholder for making payment of purchases online. The vendor gets the amount from the buyer through credit or debit Con’d. The amount gets immediately transferred to Vendor’s Bank Account. After the successful transfer of funds, goods are delivered by the vendor to buyer.
• Digital cash: This facility of electronic currency exists only in cyberspace. For making payment of purchases, online digital cash offers the ability to use real currency in an electronic format.

Buying Selling Process: Information relating to buying and selling is exchanged in traditional business and also in online (internet) business. In comparison to traditional, business, online business is more easier. In traditional business, time is required to visit the shop, to negotiate, to convince and the presence of buyer and seller is required for face to face interaction. So, to complete the deal lot of time is wasted. However, in online transactions all information is provided with terms and conditions and it is free from most of the problems as that of traditional business. Hence online transactions are result oriented and more easier than traditional business.

Outsourcing-

Meaning: Outsourcing is a process of an allocation of specific business processes or functions, mostly the non-core, to a specialised agency for certain monetary consideration. Usually, establishment, firms, corporate organisations, hospitals, malls, housing societies etc. outsource their non-core business areas such as security service, sanitation, household pantry, etc.

In outsourcing, the company benefits in two ways, viz. (i) It helps to reduce the company’s own cost and (ii) The company uses expertise of the specialised agencies to perform its business processes in a better way. Nowadays some functions like wedding, anniversary, birthday celebration, etc. are also outsourced to specialised agencies.

Need for Outsourcing:

• Some services require finely tuned skills which organisation cannot provide.
• Non-core business areas are outsourced to concentrate on improvement of quality of their products and services.
• Sometimes an organisation cannot handle all the functions internally.
• Some processes are required to perform once in several years.

Advantages of Outsourcing:

• Overall cost advantages: Outsourcing reduces its own overall cost. It saves cost of training, saves time and efforts on training.
• Stimulates entrepreneurship, employment and expertness: Outsourcing encourages and stimulates entrepreneurship, employment and expertness in the country from where outsourcing is done.
• Low manpower cost: Manpower through j outsourcing is available at much lower cost.
• Access to professional, expert and high quality services: The tasks are outsourced to the vendors who are specialised in their fields. They have deep knowledge, experience, specific equipment and technical expertise. They give better j performance and commit less errors.
• Emphasis on core process rather than the supporting ones: Outsourcing facilitates the organisation to spend more time to strengthen ; their core business processes. The organisations ! can easily focus their attention on improving the quality of their products and services.
• Investment requirements are reduced: When some areas of business are outsourced to specialised agencies, the parent organisation is not required to invest in latest technology, software and infrastructure. Hence investment requirement of the parent organisation is very less.
• Increased efficiency and productivity: Outsourcing increases efficiency and productivity j in the non-core area of an organisation.
• Knowledge sharing: While working in the organisation outsourced partners and employees of parent organisation share their knowledge, experience, technical expertise, etc. with each other.
• This is one of the prime advantages of outsourcing, This in turn develop both the companies and: enhance goodwill in the industry.

Disadvantages of Outsourcing:

• Lack of customer focus: An outsourced vendor may be catering to the expertise needs of several companies at a time. In such cases, he may lack focus and concentration on the parent company’s need or task. As a result, the quality of service given may not remain up to the mark.
• A threat to security and confidentiality: Outsourcing involves a risk of exposing confidential and secret information of the organisation to a third party. So, there is also danger of the misuse of company’s confidential information by the contractors.
• Dissatisfactory services: Some common problems of outsourcing include delayed (stretched) delivery and sub-standard (dissatisfactory) quality.
• Ethical issues: When some functions are outsourced to the foreign company, the unemployment problem of parent company and country gets worse. This is one of the ethical issues related to outsourcing.
• Other disadvantages: When business functions are outsourced, the parent company has to suffer disadvantages like misunderstanding of contracts, lack of communication, poor quality and delayed services.

Different Forms of Outsourcing-

Business Process Outsourcing (BPO):

Meaning: BPO implies outsourcing of peripheral or non-primary business functions of the organisation to an external organisation (service provider) to minimise cost and increase efficiency. It means to give contracts or responsibilities of specific business process to third party e.g. customer care centres of various banks.

Advantages of BPO:

• Productivity improvement: Outsourced business processes are performed by educated or skilled people more efficiently and hence productivity of the organisation improves.
• Optimum utilisation: BPO facilitates the parent organisation to utilise its available scarce resources up to their optimum level possible.
• Reduction in cost: BPO is more important to any organisation as it helps in reducing cost, increasing productivity and revenues of an organisation.
• Improved human resources: Outsourcing helps the parent organisation to get skilled and trained personnel (manpower) at low rates.

Disadvantages of BPO:

• Communication problems: The misunder¬standing and miscommunication between parent company and vendor company may lead to communication gap.
• Different time zones: Sometimes, the parent company and vendor company function in two different time zones. This may create many problems during online meeting, communication, etc.
• Loss of Control: On account of time differences and communication errors, the parent company may sometimes lose control over its project.

Knowledge Process Outsourcing (KPO)-

Meaning: KPO is form of outsourcing in which knowledge related and information related work is outsourced to third party service providers. KPO is sub segment of BPO in which outsource service provider is hired to perform particular business function and to provide expertise around it. In KPO advanced analytical and technical skills and high degree of specialist expertise are required. The processes of specialised and knowledge based are outsourced to KPO which help in value additions.
KPO may be in the same country or at an off shore location.

Advantages:

• Cost reduction: In KPO, cost reduction is possible as parent company gets professional services at a cost effective price.
• Skilled personnel: The company can easily hired skilled employees from KPO service providers.
• Reduction in unemployment: Skilled and high end services are available at lower cost, reduce unemployment and provide benefits to the economy.
• Flexibility: KPO provides flexibility in terms of Human Resource Management (HRM) and Time Management.

Disadvantages:

• Security Problem: Many a time client organisation may have to face security problems because of leakage of secret information by the service providers.
• No assurance of quality work: The character of outsourced workers and the quality of work cannot be assured.
• Time consuming: KPO is time consuming process and cannot provide quick solution to the
  company who need immediate results.
• Complication: Communication gap due to legal, cultural and language barriers may lead to complications.
• Language barrier: Language barrier creates communication problem.

Legal Process Outsourcing (LPO)-

Meaning: LPO is a form of outsourcing in which legal services ranging from drafting legal documents, performing legal research to offering legal advices are provided by law firm for certain consideration in money term. In this, in-house legal departments outsource legal work which can S be done at lesser cost. LPO has gained tremendous i ground in India in recent years. It has been giving | services like document review, legal research, writing, drafting, briefing, etc.

Advantages:

• Cost savings: Considerable cost is saved by outsourcing legal functions to specialised law firm.
• Access to high talent: Outsourcing the | legal work to law form allows the client company | to get high talent and niche expertise that does not j exist in its own company.
• Division of workload: Utilisation of external and in-house talent permits the law firm and parent organisation to divide their liabilities in response to workload and client demands. Firm’s overhead reduces due to flexible staffing.

Disadvantages:

• Problem of authenticity: The client organisation is required to share some important document with legal firms. This creates the problem of authenticity (trustworthy).
• Problem of in-depth knowledge: There may be a problem of detail or thorough knowledge of all relevant laws.
• Communication problem: The cultural and language barriers hinder effective communication between domestic organisation and international team.
• Geographical problem: LPO affects adversely by geographical distance (hurdles) between client organisation and law firms.

By going through these Maharashtra State Board Organisation of Commerce and Management 12th Notes Chapter 6 Social Responsibilities of Business students can recall all the concepts quickly.

Maharashtra State Board Organisation of Commerce and Management 12th Notes Chapter 6 Social Responsibilities of Business

→ Social Responsibility – Social Responsibility refers to all such duties and obligations of the business that are directed towards the welfare of society.

→ Legal Pc Legal responsibility refers to all such duties and obligations of the business that are prescribed by law. It may be fulfilled by mere compliance with the law.

→ Trusteeship’ – According to the principle of trusteeship that was propounded by Mahatma Gandhi, “A business must be carried out in trust, legally and morally for the benefit and welfare of the people.”

→ Fringe benefits: A benefit to employees in kind or in service, the cost of which is borne by the employer. They include profit-sharing schemes, bonuses and medical schemes, sick pay, holidays, etc.

→ Job Security: It is an assurance that an employee has about the continuity of gainful employment
for his/her work life.

→ Trade Union: An association of employees who have come together to improve their wages, hours and conditions of employment by means of collective bargaining.

→ ‘Divide and rule’ Policy: The policy of maintaining control over one’s subordinates or opponents by
encouraging dissent between them thereby preventing them from uniting in opposition.

→ Anti-Social Activ: It covers a wide range of unlawful activity that causes harm to an individual, to their community or to their environment.

→ Business Ethics: It is a code of conduct for regulating the activities of business towards society or others.

→ Moral Values: Moral values are the standards of right and wrong which govern an individual’s behaviour and choices.

→ Social Values: Social values are a set of moral principles that provides the general guidelines for social conduct. Values such as fundamental rights, patriotism, respect for human dignity, rationality, sacrifice, equality, democracy, etc. influence our behaviour in many ways.

→ Corporate Social Responsibility (C.S.R.): C.S.R in the integration of socially beneficial programmes and practices into corporation business model and culture. It aims to produce an overall positive impact on society.

→ Dumping: In International trade, the practice of a producer or supplier, usually monopolist, who sells a product at a lower price in a foreign country than in the home market.

→ Insider trading: The managerial personnel as well as top officials have access to the confidential and sensitive information of the company. These persons may misuse such information for their own or other persons’ benefits. The misuse of sensitive information may lead to fraud or rigging of the prices of shares. This is called ‘insider trading’.

→ Warranty: A written guarantee given to a purchaser that the manufacturer, dealer, etc. will make repairs or replace defective parts free of charge for a stated period of time.

→ Resources: Capital fund, tools, machinery, vehicles, power supply, employees, etc., that an enterprise uses to carry out its activities.

→ Public image: The general impression of a business organization gained and held by its own employed personnel or by and large based upon the presentation of its activities and the reputation of its products.

→ Natural calamities: A disaster or misfortune, especially one causing distress or misery produced by nature e.g. cyclones, storms, earthquakes, famine, droughts, etc.

Introduction-

A business organization depends upon society for its continued existence and growth. Different segments of society contribute to the success of a business. The business obtains its input like manpower, money, machines, materials, etc. from its environment. No organization can survive in the absence of an environment. A business organisation depends on society both for procurement of required input and also for disposal of its output. Thus, it becomes important that businesses should do something for society in return. This responsibility of business towards society is called Social Responsibility.

The concept of social responsibility is as old as our civilization. In India, it has been followed since ancient times. Philosophers like Chanakya from India and pre-Christian era philosophers in the West preached and promoted the concept of social responsibility and other ethical principles while doing business.

Concept of Social Responsibility-

Meaning:
Social responsibility is broader than legal responsibility of business. Legal responsibility may be fulfilled by mere compliance with the law but social responsibility is more than that. It is voluntary action on the part of business for the benefit of society. Thus, all the activities of business should be performed in such a manner that they will not harm any part of the society, but help to protect and contribute to the interest of the society.

Definition:
According to Howard D. Bowen, “Social Responsibility is to pursue those policies, to make those decisions, or to follow those lines of action which are desirable in terms of the objectives and values of our society.”

Need for Social Responsibility:

• Concept of Trusteeship: This concept was propounded by Mahatma Gandhi. Wealthy people who are the trustees of trusts must take care of the welfare of the people in general. Businessmen are treated as trustees of society.
• Changing expectations of society: Society’s expectations from business firms have changed from provider of goods and services to contributor towards social welfare.
• Reputation: A company which fulfils social obligations enjoys a good reputation in the society. Business should indulge in creating a favourable image and build its brand. Such a business is held in high esteem which ultimately results in increase in sales, profit, growth, etc.
• Protection of Environment: Business organisation should adopt eco-friendly practices. They should make proper use of country’s natural resources and avoid environmental degradation like pollution of water, depletion of ozone layer, etc.
• Optimum Utilisation of Resources: It is the responsibility of the business organisation to make optimum use of the resources at their disposal. Business firms should avoid wastage of resources.
• Pressure of Trade Union: It is necessary for the business organisations to understand their responsibilities towards the employees and their unions. They should avoid any conflict with them.
• Growth of Consumer Movement: Business organisation must follow fair trade practices and follow consumer oriented policies in increasing competitive market.
• Government Control: Government has enacted various laws to regulate business organisations. All these laws put moral as well legal pressure on business organisations.
• Long term self interest: Fulfilling social responsibility is in long term interest of the business organisation i.e. service to society. It can obtain support from various interest groups.
• Complexities of Social Problems: A progressive and socially aware business concern has moral obligations to help in solving social problems like discrimination at workplace, etc.
• Globalisation: In globalisation, those business organisation that have adopted good practice are influencing the entire world trade.
• Role of Media: Media can raise voice against business malpractices and exploitation of consumers. Hence, business organisation cannot ignore the social responsibilities towards different constituents of society.

Responsibility Towards Different Interest Groups-

Responsibilities Towards Owners:

• Reasonable profit: Business organisation should earn reasonable profit to bring financial stability and growth.
• Exploring business opportunities: Business should be alert to find opportunities to explore, expand, grow and diversify the business. This is very crucial for success.
• Optimum use of capital: Business organisations should use available capital carefully and efficiently by considering business risk. Management should pay attention to the safety of capital.
• Minimum wastages: Business organisations should minimise wastage of time, money, manpower, etc. to maximise profit.
• Efficient Business: Efficient and optimum use of available scarce resources by the business firm result into increase in profitability and productivity which is turn facilitates the business firm to carry on business more efficiently.
• Fair practices on stock exchanges: The business firm should avoid all types of unfair practices in relation to stock exchange such as insider trading, providing wrong and secret information, etc. It may bring unfavourable changes in share prices which lead to loss to common investors.
• Expansion and diversification: To face market competition more comfortably, business enterprises should undertake Research and Development on various projects.
• Periodic information: The business organisations should provide complete and accurate information about the financial position through reports, circulars, etc. to the owners from time to time.
• Effective use of owner’s funds: The business organisation must use owners’ fund in the best manner possible to give them short term as well as long term gains on time.
• Creating Goodwill: The management of the business enterprises should strive hard to develop and maintain good public image, respect and trust in the market.

Responsibility Towards Investors:

1) Proper conduct of meetings: The business organisations are expected to call and organise meetings of investors at regular intervals to provide information of the business. During the period of financial crisis, investors should be taken into confidence. However, in case of failure, management should explain them the factors responsible for such failure.

2) Return on investment: The business organisation are expected to give fair returns to the investors regularly on their investments in the form of interest. The business organisations are also expected to take care of investment, pay fair returns on investments and bring steady appreciation of the business.

3) Handling grievances: A company should handle the investors’ grievances properly by implementing effective methodology. All queries of other issues should be answered satisfactorily.

4) Maintain transparency : The investors supply the funds to satisfy the long term capital and working capital needs of the business. In return, all business organisations are required to maintain high degree of transparency in their operations.

5) Proper disclosure of information: The management of the business firms are expected to provide full and factual information to the investors regularly through reports, circulars, statement of profit, etc. These information of financial performance of the business must be correct. This is because prospective investors take decisions to invest in future on the basis of information so provided.

6) Maintain solvency and prestige: The business organisations are expected to maintain solvency, prestige, goodwill and sound financial position to win confidence of their investors. They should continuously strive to undertake research, innovation and expansion programme.

Responsibilities Towards Employees:

1) Job security: It is responsibility of business enterprises to provide security or guarantee of job to their employees. This will provide them mental peace and encourage them to work with full concentration and dedication. This will also help to raise employees morale and loyalty towards the organisation.

2) Fair remuneration: The business organi¬sations are expected to pay attractive salaries and other incentives like overtime allowance, bonus, etc to all employees. Remuneration should be determined according to the nature of work. The business organisation should also adopt suitable wage plans, giving increment and revision of wages from time to time.

3) Healthy and safety measures: The business enterprises are required to protect health and hygiene of employees by providing good canteen, medical and sanitation facilities, to prevent accidents. To control pollution, proper maintenance of machines and premises should be done regularly. Safety equipment such as safety shoes, hand gloves, masks, goggles, helmets, etc. should be provided to the workers.

4) Good working conditions: The business organisations must provide good working conditions like adequate lighting, ventilation, safe drinking water and take necessary steps to avoid air, sound and water pollution. They should also decide proper working hours with lunch breaks and other facilities.

5) Recognition of Trade Unions: Every employer or company must recognise the employee’s right to join and form trade union. Management should not follow ‘divide and rule’ policy. Management should solve the problems of workers through talks or negotiations with trade union. Both should agree to ban strikes and lockouts to protect their interest.

6) Education and training: The business enterprises are expected to educate the employees through guidance and training according to the nature of job. To keep employees updated with latest developments, introduction training and refresher training should be arranged at regular intervals by their employers. Training is necessary to increase efficiency and confidence of employees.

7) Workers participation in management: The business organisations must encourage the employees to participate in the management through formation of workers committee. Management should also encourage suggestion schemes, profit sharing to raise employees morale and to give them sense of belongingness.

8) Promotion and career opportunities: Every business organisation is expected to give sufficient opportunities of promotion to their talented employees. Organisation should give information regarding qualification, skill and experience needed to get promotion. This will enhance awareness among the employees.

9) Proper grievance procedure: The business organisations are expected to lay down proper grievance procedure to handle employee’s problems, complaints, queries without any delay. Investigation and necessary steps must be taken to settle their grievances.

10) Miscellaneous: The business organisations are expected: (i) to give fair treatment to all employees, (ii) to recognize, appreciate and encourage special skills of employees, (iii) to introduce code of conduct, (iv) to provide enough opportunities for meaningful work and to recognize goals, (v) to protect religious, social political rights of employees and (vi) allowing formation of informal groups.

Responsibilities Towards Consumers:

1) Good quality products: It is the respon¬sibility of business organisation to produce better quality products. For this purpose, every business unit should have quality control department to reject inferior and substandard products. In this respect, ISO is considered as the latest tool towards quality control. This ensures customer loyalty to the products.

2) Fair prices ; The business organisations must charge fair and reasonable prices for their products. Maximum Retail Price (M.R.P) inclusive of all taxes should be printed on all packed products. The customers should not be cheated by charging high prices.

3) Customer’s safety: The business organi¬sations should not sell harmful (unsafe) goods or goods that make adverse effect on the life and health of the customers.

4) Honest advertising: Advertisement conveys information of products, their facts, features, advantages, side effects, uses, etc. The business organisations must see that their advertisements are honest and do not mislead the consumers. It should not indulge in false, misleading and vulgar advertisement.

5) After sales service: The business organisations are expected to provide efficient and effective after sales service to establish good relation with the customers.

6) Research and Development: The business organisations are expected to conduct research and development to improve quality of goods and to reduce the total cost of production. They should apply for quality standards like BIS or AGMARK on their products.

7) Regular supply: The business organisation must supply goods and services to the consumers regularly. The business firms should not create artificial shortage through hoarding and black marketing.

8) Attend complaints: The business firms must attend consumers’ complaints without delay through implementation of effective grievances redressal system.

9) Training: The business firms should arrange training for their customers either free of charge or by charging nominal fees.

10) Avoid customer exploitation: The business organisation should avoid adoption of unfair trade practices and monopolistic competition to protect the interest of the consumers.

Responsibilities Towards Government:

• Timely payment of taxes: The business organisation are expected to pay various taxes such as sales tax, income tax, wealth tax, etc. levied by the government from time to time. This helps the government to take up various development projects.
• Observing rules and regulations: The business organisations are expected to comply with the various laws and regulations enacted by the government. They should observe the laws in relation to obtaining license, operation of business, price determination and production, etc. and conduct business in lawful manner.
• Earning foreign exchange: The business organisation carrying on business on large scale are expected to export their products to foreign countries to earn foreign exchange. The government needs foreign exchange to import valuables and important products.
• Economic Development: The business organisation Eire expected to give necessary co-operation to the government in balanced and rapid economic development of the country.
• Implementing socio-economic policies: The business organisation are expected to provide required co-operation and help to the government in implementation of various socio-economic programmes and policies.
• Suggestions to government: The business organisations should give suggestions to the government before framing important policies such as Industrial Policy, Import-Export Policy, Licensing Policy, etc.
• No favours: The business organisations should not give bribe or influence any government officials to get any favour for doing their work.
• Contributing to government treasury: The business organisation must give financial help to the government during emergency and occurrence of natural calamities such as earthquakes, floods, cyclones, etc.

Responsibilities Towards Community/ Society/Public in General:

• Protection of environment: In recent years, pollution has become the major problem. Industries, chemical plants, cement plants, etc. create air and water pollution. The business firms must take all possible measures to minimise or avoid pollution.
• Better and maximum use of resources: The business organisations are expected to make proper, efficient and optimum use of available scarce resources like water, fuel, land, etc.
• Reservation for weaker section: The business organisations are expected to reserve certain positions in their organisation for financially weaker sections of the society. The poor people also expect financial and other help from the business firms which must be provided regularly.
• Development of backward regions:The society expects that business organisations start their industries in backward areas to create employment opportunities, increase purchasing power among people and facilitate development of backward regions.
• Protest against anti-social activities:The business organisations should not indulge in anti¬social activities which will adversely affect the society. They should not provide any financial help to support anti-social activities. Anti-social activities such as smuggling, association with underworld people, bribing government officials, etc. should be avoided by the business organisations.
• Financial assistance: The business organi¬sations are expected to provide financial assistance and donations to the society for various social activities such as eradication of poverty and illiteracy, arranging anti-drug campaigns, anti noise pollution campaigns, etc.
• Prevent congestions: The business organi¬sations should avoid crowding of industries in cities by shifting and establishing industries in different industrial zones or location. This will minimise adverse effect on residential areas.
• Employment generation: The business organisations should generate large employment opportunities for all sections of the society through expansion and diversification programmes. This will reduce and help to solve the burning problem of unemployment, poverty, etc.

Social Responsibility towards Protection of Environment-

Business organisations are under obligation to protect and promote environment. For manufacturing goods and services business enterprises use all types of resources from the nature. Working of business organisations create imbalance in original state of nature. The development is responsible for its degradation. It is the responsibility of every business organisation to protect environment and not to create imbalance in nature. The diagram showing how business organisations influence environment is given below:

Rapid industrialisation results in environmental pollution through generation of waste and loss of bio-diversity and releasing genetically modified organisms and toxics. Through the use of natural resources the business organisation degrade the bio-physical environment.

Effect of Business on Environment:

• Air pollution: Air pollution is created by release of different types of harmful gases into the atmosphere, smokes and emissions of toxic fumes from burning of coal and vehicles.
• Water pollution: Harmful chemical fertilizers, pesticides, industrial waste, distilleries waste, e-waste, etc. when mixed with water, create water pollution.
• Sound pollution: Increase in number of industries, transportation, machinery, aeroplanes, etc. create unbearable sound pollution.
• Electronic Garbage: Wastage created from mobile, TV sets, laptops, etc. Eire not properly destroyed by many industries. Various products like lead, cadmium, chromium are called electronic garbage.

Waste prevention technique: The waste preventive techniques are summarised and called as 4 R’s i.e. Reduction, Reuse, Recycling and Recovery.

• Reduction: This preventive technique suggests that wherever possible wastage of resources should be reduced.
• Reuse: This preventive technique states that if waste is produced, wasted materials or by¬products should be reused if it is practicable and possible.
• Recycle: This preventive technique gives option that wastage that cannot be reduced or reused should be recycled.
• Recovery: This preventive technique suggests that recover energy or materials from the . waste which cannot be reduced, reused or recycled.

Business Ethics-

Concept:
The word ‘Ethic’ is originated from Greek word ‘Ethos’ which implies ‘human character and conduct’. Accordingly, the term ethics refers to the set of rules and principles that every organisation should adopt. In other words, business ethics refers to the code of conduct that business
organisations should follow while doing their business. Ethic is a branch of social science which deals with the concepts, such as right and wrong, just and unjust, proper and improper, legal and illegal, fair and unfair, good and bad, etc. in respect to human behaviour and actions.

Definitions:
According to Wheelers, “Business Ethics is an art of science of maintaining harmonious relationship with society, its various groups and institution as well as recognising the moral responsibility for right or wrong conduct of business.”

Features of Business Ethics:

• Code of conduct: Business ethics is a code of conduct which businessmen must follow while doing the business. It explains what to do and what not to do for the well-being of the society.
• Based on moral and social values: Business ethics are based on the moral and social principles which includes self control, consumer protection and welfare, services to society, fair treatment to all, etc.
• Gives protection to social groups: Business ethics provides protection to different social groups like consumers, small businessmen, employees, shareholders, creditors, government, etc.
• Provides basic framework: Business ethics provides social, economic, cultural, legal and other limits to the organisations in which they must conduct their business activities.
• Voluntary: The businessmen must accept the business ethics on their own voluntarily. Its acceptance cannot be enforced by law.
• Requires education and guidance: The businessmen should be properly educated, motivated and given guidance before implementing business ethics.
• Relative term: Business ethics differs from one business to another, from one country to another. What is considered good in one country may not be accepted in other country.
• New concept: Business ethics is a newest concept developed in recent years. It is strictly followed only in advanced countries and not in underdeveloped and developing countries.

Moral and Social Values:

Values such as fundamental rights, patriotism, human dignity, sacrifice, equality, democracy, etc. give a direction to grow and integrate our personality. Social values are considered as an important part of the culture of the society. Social values of the business form the base for social responsibilities. They provide general guidelines for social conduct. Social values are usually based on tradition, co-operation, ego, honesty, integrity, hard work, fairness, forgiveness, etc. Moral values such as not to indulge in unfair trade practices, to be honest and truthful about quality, etc. should be followed while doing the business.
Society has created rules regarding type of activities business should do and should not do. These are called business ethics.

The code of business ethics:

Do’s:

• The business should pay taxes and other charges regularly.
• They must pay fair wages, allowances and other monetary incentives to workers.
• They should ensure safety and security of their product.
• The business firms should supply quality goods as per expectations of consumers at reasonable prices.
• The business should give due respect and honour basic to rights of consumers.
• The business must use a part of profit for the well-being of the society.

Don’ts:

• The business organisation should not destroy healthy competition.
• The businessmen should not cheat or exploit customers.
• They should not create monopoly.
• They should not resort to hoardings or black marketing.
• They should not create secret or unreasonable profit.

Avoid:

• The businessmen or organisations should avoid unfair competition.
• The businessmen should avoid concentration of economic power.
• They should not make agreement with fellow businessmen for controlling production, distribution, pricing, etc.

Accept:

• The businessmen should accept principle of “service first and profit next”.
• They should accept the truth in business that “Customer is the king”.
• They should make business just, fair, human, efficient and dynamic.

Corporate Social Responsibility-

Meaning:
Corporate Social Responsibility (CSR) makes a company socially responsible and accountable. It aims to contribute to societal goals or support volunteering or ethically-oriented practices.
The Ministry of Corporate Affairs in India has notified which makes mandatory for certain companies to comply with the provisions of CSR.

Definition:
According to UNIDO (United Nations Industrial Development Organisation), “Corporate Social Responsibility is a management concept whereby companies integrate social and environmental concerns in their business operations and interactions with their stakeholders. ”

Scope of CSR:

(A) Applicability of CSR:

• The companies having net worth of ₹ 1500 crore or more or turnover of ₹ 1000 crore or more or net profit of ₹ 15 crore or more during any financial year shall be required to constitute a corporate social responsibility committee with effect from 1st April, 2014.
• These companies must spend, every financial year, at least 2% of the average net profit of the company made during the three immediately preceding financial years, in pursuance of its CSR policy.

(B) CSR committee:

• The CSR committee consist of four directors who shall meet at least twice in a year to discuss and review CSR activities and policy.
• The committee will recommend CSR activities, prepare budget, monitor progress, etc.

(C) CSR activities:

• Eradicating hunger and poverty
• Health care & sanitation
• Education & employment enhancing vocational skills, livelihood enhancement projects
• Reducing child mortality
• Environmental sustainability and ecological balance & conservation of natural resources
• Rural development & slum area development projects.

(D) Allocation of funds:
The company would spend not less than 2 % of average net profits of the company made during three immediately proceeding financial years.

(E) Non-compliance of CSR activities:
Penalties for non-complying the duty of CSR would attract a fine of not less than ₹ 50,000 which may extend to ₹ 25,00 000 and every officer of the company in default shall be punishable with imprisonment up to 3 years or with fine which shall not be less than ₹ 50,000 which may extend to ₹ 5,00,000 or both.

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 7 Plant Growth and Mineral Nutrition students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 7 Plant Growth and Mineral Nutrition

Plant Growth-

1. Growth is a characteristic feature of living organisms.
2. Aspects of Growth

1. Quantitative
2. Qualitative

Quantitative: Increase in length size, volume, numbers body mass, dry weight, etc.

Qualitative

• Change in nature of growth
• Development – orderly progress
• Differentiation – complex state

3. Growth : A permanent irreversible increase in the bulk of an organism, accompanied by change in the form.

4. Growth in multicellular/vascular plants

1. Indeterminate
2. Indefinite
3. Restricted to specific regions
   Meristems -Apical, Intercalary and lateral.

5. In unicellular plants, determinate and uniform growth is observed, while in multicellular plants certain organs like leaf, flowers and fruits show determinate growth.

Phases of growth-

1. Phase of cell division/cell formation :

• Meristematic cells – thin walled cells
• Mitotic division → 2 cells → out of these one remains meristematic and other undergoes differentiation.
• Slow rate of growth – i.e. Lag phase

2. Phase of cell enlargement/cell elongation :

• Newly formed cell absorbs water and becomes turgid.
• Osmotically active cell → Turgidity leads to cell enlargement
• Synthesis of new wall material
• Accelerated pace of growth – Log phase or exponential

3. Phase of cell maturation / Cell differentiation :

• Enlarged cell become specialized
• Cells attain maturity – morphological and physiological features
• Cells get equipped to perform specific function
• Steady state, rate of growth slow down -stationary phase

Conditions for growth-

1. Physiological conditions

2. Environmental Conditions

Growth rate and types of growth –

1. Growth in plants can be measured as increase in

2. Various methods for measurement of linear growth :

• Direct method : Measurement with scale
• Horizontal microscope : Useful for measuring growth in fields.
• Auxanometer : For linear growth of shoot – 2 types – Arc auxanometer and Pfeffer’s auxanometer.
• Crescograph : Record of primary growth, information of growth per second. It is developed by Sir J. C. Bose.

3. Growth Rate/Efficiency index : Increased growth per unit time. e.g. Increase in area of leaf, size of flower, etc.
4. Absolute growth rate (AGR) : Ratio of change in cell number (dn) over time interval (dt)
i. e. AGR = \(\frac{d n}{d t}\) i.e. total growth per unit time.
5. Relative growth ratio (RGR) : AGR when divided by total number of cells present i.e. growth of given system i.e. RGR = \(\frac{\mathrm{AGR}}{n}\)i.e. ratio of growth in given time / initial growth.
6. For describing cell growth in culture AGR and RGR are useful.
7. Types of Growth

• Arithmetic
• Geometric:

Arithmetic

• Rate of growth constant hence linear curve
• e.g. elongation of root
• Mitosis of cell → 2 cells one divides further and other differentiation and maturation
• Mathematical expression Lt = L₀ + rt

Where Lt = Length at time ‘t’
L₀ = Length at time zero
r = Growth rate
t = Time of growth

Geometric:

• Rate of growth slow initially and then exponential rate. J shaped curve.
• e.g. Embro – Initial stages of zygote division
  Mitosis of cell → 2 cells
  Both cells continue to divide and
  redivide
• Mathematical expression
  W₁ = W₀e^rt

Where W₁ = Final size
W₀ = Initial size
e = base of natural log
r = Growth rate
t = time of growth.

Growth curve-

1. Graphic representation of the total growth against time is known as growth CurVe.
2. Types of Growth curve – Graphs
   
3. Growth rate is low in lag phase, faster growth rate reaching maximum in exponential or log phase and is gradually slows down in stationary phase. –
4. Sigmoid curve is obtained when rate of growth plotted against time for all three phases.
5. Grand period of growth (GPG) : The total period required for all phases (Lag, log and stationary) to occur is called grand period of growth.

Differentiation, De-differentiation, Re-differentiation-

1. Differentiation : It is the permanent change in structure and function of cells leading to maturation.

• Maturation of cells derived from apical meristems.
• Major anatomical and physiological changes occur.

2. De-differentiation : It is a process or ability where living differentiated cells regain the capacity to divide thus permanent cells become meristematic. e.g. Cork cambium, Parenchyma cells forming interfascicular cambium for secondary growth.

3. Re-differentiation : The de-differentiated cells lose their capacity to divide and mature for the specific function, e.g. Secondary xylem and secondary phloem formed from de-differentiated cambium.

Development-

• It is an orderly process of progressive changes in shape, its form and also complexity.
• In plant it includes all sequential events in its life cycle, viz. – Seed germination → Meristem → Cell division → Plasmatic growth → Cell elongation → Cell maturation → Mature cell → Senescence → Death
• Thus growth, morphogenesis, maturation and senescence are included in development.

Plasticity-

• Plasticity : It is capacity of being moulded or modelled.
• In plants, plasticity is ability to form different types of structures in response to external environmental stimuli or internal stimuli. (Intrinsic plasticity)
• Plasticity is noticed in various phases of life. e.g. different form’s of leaves in same plant – cotton, coriander, larkspur (Delphinium) i.e. heterophylly in juvenile and adult stage.
• Environmental Plasicity is observed in Butter cup (Ranunculus Flabellasis).
  Heterophylly where aquatic habitat has dissected leaves and in terrestrial habitat broadly lobed leaves.

Growth Hormones-

• Starling coined the term hormone in animal physiology.
• Growth Regulators or Growth Hormones – These are the internal factors which influence growth i.e. inhibit, promote or modify growth.
• Growth Harmones:

• Plant hormones are organic substances produced naturally that affect growth or other physiological functions at a site away from their place of production.
• To evoke the response hormones are needed in very small amount and they are mainly transported through phloem parenchyma.

6. Auxins : Term given by F.W. Went

• First isolated from human urine, while in plants synthesised in apical meristematic region.
• LAA – i.e. Indole 3 acetic acid – most common natural auxin, synthesised from amino acid Tryptophan.
• Synthetic auxins – IBA (Indole butyric acid), NAA (Naphthalene acetic acid), 2, 4-D (dichloro Phenoxy acetic acid).

Physiological effects and applications of auxins :

• Cell elongation and cell enlargement
• Apical dominance – Growing apical bud inhibits growth of lateral buds
• Stimulation of growth of root and stem
• Multiplication of cells hence utilized in tissue culture
• Formation of lateral and adventitious roots
• 2, 4-D is selective herbicide – kills dicot weeds
• Induced parthenocarpy – seedless grapes, : banana, lemon, orange
• Promote cell division and early differentiation I of vascular tissue xylem and phloem.
• Induces early rooting in cutting method of : artificial vegetative propagation.
• Foliar spray of synthetic auxins – Flowering ; induced in litchi and pineapple, prevents : early fruit drop of apple, pear and oranges, prevents formation of abscission layer.
• Increase in rate of respiration.
• Break seed dormancy and promote seed germination.

Gibberellins (GA) : Named by Yabuta and Sumuki:

• First isolated from fungus Gibberella fujikuroi by Kurasawa.
• Rice seedlings show Bakane disease with stem elongation due to this fungus infestation. ;
• Yabuta and Sumuki isolated it from fungus culture.
• Synthesised from mevalonic acid in young leaves, seeds and root, stem tips.
• GA₃ is most common and biologically active – Contains gibbeane ring.

Physiological effects and applications of Gibberellins :

• Breaking of bud dormancy, seed dormancy,
• By promoting synthesis of amylase in cereals, their seed germination can be stimulated e.g. wheat, barley.
• Increase in length of internodes thereby elongation of stem.
• Bolting in rosette plants – elongation of internodes before flowering e.g. Cabbage, beet.
• Parthenocarpy in tomato, apple, pear.
• Stimulates flowering in long day plants.
• Increase in fruit size and bunch length e.g. grapes.
• Overcomes effects of vernalization.
• Inhibition of root growth, delay senescence and abscission. .
• Production of male flowers on female plants.
• They convert genetically dwarf plants to phenotypically tall plants e.g. maize.

Cytokinin : Term coined by Letham.

• Promote cell division – Natural source – Banana flowers, apple and tomato fruits.
• Discovered by Skoog and Miller in Callus culture of Tobacco – by supplementing media with coconut milk.
• Present in herring (fish) sperm DNA – Kinetin.
• Cytokinins are derivatives of adenine, a purine base. Chemically 6-furfuryl amino purine.
• First natural cytokinin obtained by Letham from maize grain Zeatin.
• Synthetic hormone – 6 benzyl adenine.
• Important in plant tissue culture (callus) for morphogenesis.

Physiological effects and applications of cytokinin :

• Promote cell division and cell enlargement
• Promote shoot formation, buds
• Cytokinin and auxin ratio controls morphogenesis.
• Growth of lateral buds, controls apical dominance
• Delay of ageing and senescence, also abscission
• Formation of interfascicular cambium
• Breaks dormancy, promotes germination
• Reverse apical dominance effect
• Induce RNA synthesis

9. Ethylene : Denny reported effect in fruit ripening.

• Gane reported natural synthesis of this gaseous hormone in plants.
• Synthesised in roots, shoot apical meristems and fruits during ripening.
• It is an unsaturated, colourless, hydrocarbon gas
• Commercially used source – Ethephon
• Described as ripening hormone.

Physiological effects and applications of ethylene :

• Promotes ripening of fruits
• Stimulates initiation of lateral roots
• Breaks dormancy of buds and seeds.
• Acceleration of abscission activity by forming abscission layer.
• Inhibits growth of lateral buds, i.e. apical dominance.
• Retardation of flowering.
• Enhancement of senescence.
• Epinasty – Drooping of leaves and flowers e.g. Pineapple.
• Degreening effect – Stimulate activity of enzyme chlorophyllase causing loss of green colour in fruits of Banana, Citrus.

Abscissic Acid :

• Responsible for shedding of cotton balls and was named as abscisin I and II by Carns and Addicott.
• Isolated from buds of Acer that causes bud dormancy, substance named Dormin by Wareing.
• These substances were renamed abscissic acid, chemically 15 – C sesquiterpenoid – synthesised from mevalonic acid.
• Leaves, fruits, roots, seeds synthesise this.

Physiological effects and applications of ABA :

• Promote abscission of leaves – beneficial for stress – drought
• Induces dormancy in buds and seeds.
• Accelerates senescence of leaves, flowers and fruits.
• Delay of cell division, cell elongation and suppression of cambial activity – Inhibit mitosis.
• Causes efflux of K ions from guard cells and thus closure of stomata – used as
  antitranspirant.
• Stress hormone – Overcome stress by inducing dormancy, inhibiting growth thus face adverse environmental conditions.
• Inhibit flowering in long day plants and stimulate flowering in short day plants. Inhibits growth stimulated by gibberellin.

Photoperiodism-

1. Influence on Reproductive Growth –

Flowering :

1. Environmental factors
2. Nutritional factors

Environmental factors:

• Light -> Photoperiodism factors
• Temperature -> Vernalization

2. Effects of Light

Processes affected:

1. Seed germination
2. VegetatIve growth
3. PhotosynthesIs

Mode/manner/aspect:

1. Quality of light
2. Intensity of light
3. Duration of light

3. Photoperiodism – Term coined by Garner and Allard.
4. Duration of light has a major effect on flowering.
5. Response of plants to the relative length of light and dark periods with reference to flower initiation is called photoperiodism.
6. Critical photoperiod : It is that duration of photoperiod above or below which flowering occurs.

7. Classification of plants based on photoperiodism:

8. Short Day Plants (SDP) or Long night plants Winter flowering

• Show flowering when day length is shorter than the critical photoperiod.
• These plants need long uninterrupted dark period.
• Flowering in SDP is affected if the dark period is interrupted even by short duration (Flash : of light).

9. Long Day Plants (LDP) or Short night plants : Summer flowering

• Show flowering when longer duration of light than the critical photoperiod.
• These plants need short dark period.
• Flowering is observed if long dark period is interrupted by brief light exposure (flash).

10. Day neutral plants (DNP) :

• Flowering in these plants is independent of duration of light.
• No requirement of specific dark or light period.
• Flowering is observed throughout the year.

11. Phytochrome : Discovered by Hendricks and ; Borthwick.

• Pigment system in plants that receives the stimulus for photoperiodism.
• In short day plants, flowering is not observed if dark period is interrupted by brief exposure to red light of 660 nm but if it is exposed immediately to far red light of 730 nm flowering is observed.
• Proteinaceous pigments present in leaves.
• Exist in two interconvertible forms P_r and P_fr.
• P_fr absorbs far red light and it is changed to P_r and when P_r absorbs red light it is changed to P_fr (biologically active form).
• Phytochromes are situated in cell membrane of chlorophyllous cells of leaves.

12. During day time Pfr accumulates in leaves and stimulates flowering in LDP but inhibits flowering in SDP
13. During night (dark) Pfr converted to Pr ‘and stimulate flowering in SDP but inhibits flowering in LDP
14. In plants, morphogenesis is controlled by both light and phytochromes and hence it is known as photomorphogenesis.
15. Photoperiodic stimulus is chemical stimulus called florigen which is hormonal in nature and is transported through phloem.

Vernalization-

• It is influence of low temperature on flowering in plants. The term vernalization was coined by Lysenko.
• Temperature influences several physiological processes and reproductory growth i.e. flowering.
• Klippart observed low temperature or chilling treatment is responsible for stimulus of early flowering.
• The seeds or seedlings are exposed to low temperatures of 1 – 6° C for about a month’s duration.
• The shoot apical meristem receives stimulus in seedlings.
• Effective in seed stage (embryo) for annual plants. Cereals and crucifers show response to low temperature pretreatments.
• The stimulus is in the form of chemical substance which is proved by grafting experiment by Melcher. It is Vernalin.
• Devernalization : It is reversal of vernalization by high temperature treatment.

Advantages:

• Crops can be produced earlier.
• Cultivation of crop possible where they do not occur naturally.

Mineral Nutrition-

1. Minerals are required by plants for synthesis of food material, i.e. inorganic substances are raw materials.
2. Soil is chief source : Solid, inorganic materials are obtained from earth’s crust.
3. Air and water are other sources from surroundings.
4. Minerals are absorbed in dissolved form usually through roots.
5. Sources of minerals :

• Atmosphere : Carbon as Carbon dioxide, Oxygen
• Water : Hydrogen, Oxygen

6. C, H, O are non-mineral major elements, structural components.
7. Classification of minerals – Based on need

1. Essential
2. Non-Essential

Essential

• Without these life cycle of plants cannot be completed.
• Important structural and functional (physiological role)
• Their unavailability causes major deficiency symptoms. e.g. C,H,O,N,R

Non-Essential

• Not indispensable for completion of life cycle.
• Do not produce or cause major deficiency.
• Needed only at specific time during growth. E.g. Bo, SI, Al

8. Classification based on requirement – quantity

1. Mac roelements
2. Microelements

Mac roelements:

• Major elements
• Required in bulk or in large amounts
• Important role in nutrition
•  Structural componcnts
  e.g. CalcIum — Ca (cell vall)
  e.g. C, H. O. R N, K, Mg. S.

Microelements:

• Minor elements
• Required in traces or small amounts
• Role as cofactors
• Act as Catalysts, activators
  e.g. Zn, Cu, Al, SI, Mn, B.

9. Recent classification is based on their functional role, i.e. on the basis of biochemical functions.
10. Symptoms of Mineral deficiency in plants :
Any visible deviation from the normal structure and function of plant is called symptom.
11. Critical concentration : Required amount or the concentration of essential element below which plant growth is retarded or affected is called critical concentration.
12. Indication of deficiency is in the form of morphological changes. It may be related to the mobility of the element in the plant body.

13. Important symptoms visible in plants :

14. Role of Mineral Elements in Plants :

15. Toxicity of Micronutrients :
Condition of toxicity : When dry weight of tissues is reduced by 10% due to mineral ion concentration it is considered as toxic to plant.

16. Uptake of one element may be affected or inhibited by toxicity of other. For e.g. Mn competes with Fe and Mg for uptake by root system and inhibits translocation of Ca to shoot apex. It leads to deficiency of Ca, Mg and Fe.

17. Mineral salt absorption : In soil minerals exist as charged particles and mineral absorption is independent of water absorption.

18. Methods of Mineral absorption

1. Passive absorption
2. Active absorption

Passive absorption

• No expenditure of energy
• By diffusion
• Direct or indirect ion exchange
• Mass flow
• Donnan equilibrium

Active absorption:

• ExpendIture of energy
• Move against concentration gradient
• ATP energy from respiration
• Accumulation of ions in root hair

19. Donnan equilibrium : Some anions after their entry inside the cell get accumulated on inner side of cell membrane.

20. Additional cations are needed to balance these accumulated anions, thus the cation concentration becomes more as they get accumulated.

21. This transport from exterior against their own concentration gradient for either cations or anions is Donnan equilibrium, which is for neutralizing the effect of accumulated cations/ anions.

22. Active absorption : It needs ATP energy which is supplied to roots from respiration. Hence when there is scarcity of oxygen available to roots there is less absorption of minerals.

23. Mineral ions accumulated in root hair reach xylem through cortical cells and further along with water carried upwards.

24. They are assimilated in organic molecules and carried further with phloem to other parts i.e. redistribution.

25. A carrier concept, where membrane proteins of root cell membrane may pump these ions into cytoplasm is suggested.

Nitrogen Cycle –

• The cyclic movement of nitrogen between atmosphere, biosphere (organisms) and soil in natural processes is a nitrogen cycle.
• Nitrogen available to plants from the environment is inert and they need it in reactive form mainly nitrate ions to utilize in synthetic processes.
• Nitrogen is a limiting element which affects productivity.
• Through biological and physical fixation it is made available to plants.
• Nitrogen fixation : Conversion of free nitrogen into nitrogenous salts to make it available to plants is called nitrogen fixation.

Nitrogen Fixation-

Physical nitrogen fixation – Atmosphere

Industrial nitrogen fixation : Haber – Bosch process

• Urea is less toxic and it is used as fertilizer.
• About 80% of nitrogen found in human tissues originate from Haber-Bosch process.

Biological nitrogen fixation :

• High energy requiring process
• To fix each molecule of nitrogen to ammonia need is 16 ATE
• Ammonia is toxic it is converted to amino acids -> Proteins

Nitrification : e.g. different soil bacteria – aerobic forms – Chemoautotrophs

• Two step process
• Ammonia converted to nitrogen dioxide (nitrite) HNOa by Nitrosomonas and Nitrosococcus.
• Nitrite converted to Nitrate by addition of oxygen by bacteria Nitrobacter.

Symbiotic N₂ fixation : e.g. Root nodules of Fabaceae plants – Pea, Bean, Gram, Groundnut have Rhizobium bacteria in it. Rhizobium also seen in soil.

Ammonification : e.g. Decomposers – Fungi, bacteria, actinomycetes
After death and decay of living organisms, ammonia is made available to plants and other microbes.

Nitrogen assimilation :

• Soil reservoir has nitrogen in nitrate, nitrite and ammonia (NH₄^–) i.e. ammonium ion.
• Uptake of these available forms from soil by plants converts and incorporates them in amino acids, nucleic acids (DNA) like organic compounds – This is assimilation.
  • In the form of biomolecules Nitrogen moves through food chain and then to decomposers.
  • Amino acids are transported to different parts for synthesis of required proteins.

Amino acid synthesis

1. Reductive aminatlon
2. Transamination

Reductive aminatlon:

• E.g. Ammonia reacting with a Ketoglutaric acid to form glutamic acid.
• Reduction reaction

Transamination:

• Glutamic acid reacting with oxaloacetic acid (OAA) to form Aspartic acid.
• Reduction reaction 2. Transfer of amino group to other Carboxylic acid

Amidation : Process of formation of amides.

• Amino acids may incorporate ammonia to produce amides. Thus these are amino acids with two amino groups.
• In presence of ATP extra amino group is attached to acidic (-COOH) group.
  
• Amides are transported via xylem vessels.

Denitrification : e.g. Anaerobic bacteria.

• Soil nitrates are converted to nitrogen gas.
• Denitrifying bacteria thus return back nitrogen from ecosystem to atmosphere.
• 2NO₃ → 2NO₂ 2NO → N₂↑
  Nitrate → Nitrous oxide → Nitric oxide → Nitrogen gas
• e.g. Bacillus spp, Paracoccus spp, Pseudomonas denitrificans.

Sedimentation : Nitrates of soil are washed away with running water or leached deep with percolating water. Thus they get accumulated and remain in the form of sediments locked and away from free circulation.

By going through these Maharashtra State Board 12th Science Chemistry Notes Chapter 16 Green Chemistry and Nanochemistry students can recall all the concepts quickly.

Maharashtra State Board 12th Chemistry Notes Chapter 16 Green Chemistry and Nanochemistry

Green chemistry: Green chemistry is the use of chemistry for pollution prevention and it designs
the chemical products and processes that reduce or eliminate the use of generation of hazardous
substances.

Sustainable development: Sustainable development is the development that meets the needs of
the present, without compromising the ability of future generations to meet their own needs.

Twelve principles of green chemistry: Twelve principles of green chemistry were proposed by Paul T. Anastas and John Warner.

12 Principles of Green Chemistry –

1. Prevention of waste or by-products
2. Atom economy
3. Less hazardous chemical synthesis
4. Designing safer chemicals
5. Use safer solvent and auxiliaries
6. Design for energy efficiency
7. Use of renewable feedstocks
8. Reduce derivatives (Minimization of steps)
9. Use of catalysis
10. Design for degradation
11. Real-time analysis for pollution prevention
12. Safer chemistry for accident prevention

The role of Green chemistry:

• Promoting innovative chemical technology to design, manufacture, and use chemical products that eliminate the generation of hazardous chemicals.
• The capital expenditure required for the prevention of pollution is controlled by the use of green chemistry.
• Green chemistry helps to protect the presence of ozone in the stratosphere.
• Global warming (The greenhouse effect) is controlled by green chemistry.

Introduction to nanochemistry:

(i) Nanoscience: Nanoscience is the study of phenomena and manipulation of materials at atomic, molecular, and macromolecular scales where properties differ significantly from those at a larger scale.

(ii) Nanotechnology: Nanotechnology is the design, characterization, production, and application of structures, devices, and systems by controlling shape and size at the nanometer scale (1 -100 nm) (1 nm = 10^-9 m). Today from clothes to computer hard drives to DVD, CD players, and even cleaning products, nanotechnology plays a big part in the manufacturing of materials.

(iii) Nanomaterial: The nanomaterial is a material having structural components with at least one dimension in the nanometer scale that is 1-100 nm. Nanomaterials are larger than single atoms but smaller than bacteria and cells. These may be nanoparticles, nanowires, nanotubes, and thin films according to dimensions. They can be further classified as zero, one, and two nanomaterial dimensions.

(iv) Nanochemistry: It is the combination of chemistry and nanoscience. It deals with designing and synthesis of materials of nanoscale with different sizes and shape, structure and composition, and their organization into functional architectures. Nanochemistry is used in chemical, physical, material science, as well as engineering, biological and medical applications.

Characteristic features of nanoparticles: Characteristic features of nanoparticles are colour, surface area, catalytic activity, thermal properties, mechanical properties, and electrical conductivity.

Synthesis of nanomaterials: (1) Bottom-up approach (2) Top-down approach.

Wet chemical synthesis of nanomaterials: A sol-gel process is an inorganic polymerization reaction. It is generally carried out at room temperature and includes four steps: hydrolysis, polycondensation, drying, and thermal decomposition. This method is widely used to prepare oxidic materials.
The reactions involved in the sol-gel process are as follows :
MOR + H₂O → MOH + ROH (hydrolysis)
metal alkoxide
MOH + ROM → M-O-M + ROH (condensation)

Analysis or characterization of nanomaterials: The nanomaterial synthesized is analyzed using the following techniques.

Different types of nanomaterials which can be synthesized are shown in the following figures:

Applications of nanoparticles:

• Nanoparticles are used in the manufacture of scratchproof eyeglasses, transport, sunscreen, crack-resistant paints, etc.
• It is used in electronic devices like Magnetoresistive Random Access Memory (MRAM).
• Silver nanoparticles are used in water purification systems to get safe drinking water.
• It is used in medicines.
• It is used in self-cleaning materials (lotus effect).

Advantages and disadvantages of nanoparticles and nanotechnology :

Advantages:

• Revolution in electronics and computing.
• Nanotechnology makes solar power more economical and energy storage more efficient.
• Nanotechnology is used in the manufacture of smart drugs which cure life-threatening diseases faster and without side effects.

Disadvantages :

• Nanotechnology causes environmental pollution which is dangerous for living organisms.
• Nanoparticles can cause lung damage.