Category: Maharashtra State Board Notes

By going through these Maharashtra State Board Organisation of Commerce and Management 12th Notes Chapter 1 Principles of Management students can recall all the concepts quickly.

Maharashtra State Board Organisation of Commerce and Management 12th Notes Chapter 1 Principles of Management

→ Team spirit : Team spirit means willingness to cooperate with each other as a part of a team or a group of people. When the entire group of employees works as a team their efforts get directed towards realising the goals of the organisation.

→ Co-operation: In the context of management, co-operation is the attitude of helping each other to achieve organisational goals.

→ Co-ordination : Integrating or linking the activities of different units of an organisation. It is the result of deliberate or consistent efforts by the management to create unity of action to achieve its goals.

→ Productivity : The degree to which a person, company, firm, etc. is able to produce efficiently. From management point of view, productivity means output per unit of input employed.

→ Goal: The aim or object towards which efforts of an individual or a group are directed.

→ Management : The art or science of directing, organising, co-ordinating, conducting, administering and controlling the work of others to achieve defined objectives.

→ Professional management : Managing the affairs of the organisation by professionally qualified persons at all the levels of management. It also means application of professional approach to manage the organisation.

→ Discrimination : Unfair treatment given to a person, a group, minority, etc.

→ Rule of Thumb : Unwritten but accepted operating practices that are considered to be average; practical and generally accepted business practices and principles. It also refers to a rough and practical approach based on experience, rather than theory.

→ Decision-making : The process of selecting from among possible alternatives. The process of decision-making involves five stages, viz. defining the problem, analysing the problem, developing of alternative solutions, selecting the best solution and converting the decision into action and its follow-up.

→ Division of labour : The specialisation of workers in particular parts or operations of production process. Application of division of labour increases skill and speed of operation, saves time and energy of the worker.

→ Remuneration : Payment of money for service or work done.

→ Moral: Of or relating to the principles of right conduct. Morals are nothing but principles and beliefs relating to right or wrong behaviour.

→ Centralisation : Imposing or placing of a high degree of control with officials at the centre or top level of an organisation, leaving little freedom of action to officials at lower levels.

→ Decentralisation : The placing of a large amount of responsibility with the officials at lower level and controlling of major and important issues rest with the top level executives.

→ Turnover : The amount of business done in a given time. It also means the rate at which workers are replaced.

→ Esprit de corps : ‘Union is Strength’. Strength of a business lies in the co-operation and harmony among its workers. It also means team work.

→ Piece rate system : It is a system of wage payment in which the wages paid to a worker are related to the result of his performance i.e. to his output rather than on the basis of time. Under this system, wages are calculated as Earnings of worker = No. of units produced x Rate per unit

→ Standard time : Amount of time it should take an average qualified worker (or group of workers) to complete a specified task.

→ Time study : Systematic observation, analysis and measurement of the separate steps in the performance of a specific job for the purpose of establishing a standard time for each performance, improving procedures and increasing quantity of production or productivity.

→ Fatigue : Physical or mental exhaustion due to exertion, long working hours without sufficient breaks, poor working conditions, target pressure, heavy working tools, etc.

→ Social responsibility : An obligation (responsibility) of the business enterprise to take those actions which promote the welfare of the society. For this, business enterprises should adopt policies that fulfill expectations, values and interest of society.

→ Scalar Chain : The hierarchy of authority from the top level to the lower level for the purpose of communication.

Introduction :

Management is necessary in all types of business organisations, non-business organisations and social activities as it is key to success in achievement of goal. To establish co- ordination among all the resources of the organisation, one must understand all about the management. Various principles, theories and techniques of management introduced and developed by the management thinkers are useful in managing the business affairs of the organisations successfully.

However, its use varying from organisation to organisation, person to person and situation to situation. Thus, in every type of organisation or in group activity, one needs to apply management principles as per nature, size and requirement of that organisation. Management co-ordinates and harmonises all the functions of the business organisation like planning, organising, staffing, controlling, etc.

Meaning and Definition :

For achieving the goals of an individual or an organisation the system or techniques which are used, adopted and accepted universally are called principles. Principles can be defined as, “a fundamental truth or proposition that serves as the foundation for a system or belief or behaviour or for a chain of reasoning.”
Management principles are statements of fundamental truth of management which act as guidelines for managerial decision-making and action. They are both descriptive and prescriptive in nature. They are universal and applicable everywhere.

Nature of Principles of Management :

(1) Universal application ; Management principles are universal in nature. They apply to all types of organisation irrespective of their type, size or nature. Their application may have to be modified but they are suitable for all kinds of organisation and even an all levels at management of the organisation.

(2) General guidelines : Management principles provide general guidelines to tackle the organisational situation in sensible way and solve the problems systematically. They are not rigid I and their application depend upon the situation, size and nature of organisation.

(3) Principles are formed by practice and experiments : The management principles are developed slowly and gradually through experiments, systematic observations and complete research work. The results of such observations and experiments are developed through regular practice in the organisations.

(4) Flexibility : Management principles although fundamental but they are flexible. They can be changed, modified or adjusted to suit an organisation and as per its need and changing situations.

(5) Behavioural in nature : Management is a team work and a group activity. Management principles are aimed and designed to influence human beings and their efforts and directed to achieve the organisational objectives.

(6) Cause and effect relationship : The management principles provide base for decision-making. They first determine the cause for particular effect, e.g. effective advertisement leads to increase in the sales.

(7) All principles are of equal importance : All principles of management have equal importance.
If any specific principle is given more importance than others, then working of the whole organisation
would affect adversely. Management principles are the principles of social science i.e. they can be applied with some modifications according to the requirements of an organisation.

Significance of Management Principles :

(1) Provides useful insight to managers : The management principles help the managers to understand and know the organisation, to improve the understanding of the situations and problems. The use and application of management principles help the managers about the manner in which they should act in different situations.

(2) Helpful in efficient utilisation of resources : The core function of management is to create and maintain proper balance between physical resources and human resources by putting them to optimum use and thereby control the wastage of resources. Through the use of different techniques and principles, management’ maintains discipline and healthy working environment to establish cordial relationship between management and employees which will increase efficiency level of employees.

(3) Scientific decisions : Management principles help the manager to handle critical situations tactfully. By using various management principles, managers learn to analyse the situations systematically, search alternative options and their results.

(4) Understanding social responsibility : Management principles guide the management in understanding social responsibility of organisation. It helps them to concentrate on providing quality products at affordable rate, avoiding unfair competition and artificial monopolistic situations in market, fair remuneration, change in environment, healthy working place, standard tools and machinery, etc.

(5) Encourages Research and Development : Management principles are dynamic as their nature changes with the changes in business world. Management principles can be modified according to the need of the organisation. Training helps to develop scientific approach towards research and development and growth and development of organisation. New techniques in the field of production, marketing, finance, human resources, etc. are discovered and developed through research and development.

(6) Helps to co-ordinate and control : Management principles serve as guidelines for the better co-ordination and control. They provide suitable systems to establish co-ordination and control.

(7) Develops objective approach : By using various management principles, the manager can develop an objective approach. The manager can find out and identify opportunities, root causes of the problems in right direction and provide appropriate solutions to the problems.

Theories of Management:

The sets of general rules which provide guidelines to the managers to enable them to manage the organisation systematically are called management theories. Some management thinkers such as Fredrick Winslow Taylor, Elton Mayo, Henry Fayol, etc. have presented different theories based on different approaches. These theories are
more suited to all types of organisations. By modifying these theories, adding some innovative techniques and strategies, managers use them in an organisation more efficiently. Thus, old theories of management provide basis for modern ; management theories.

Management theories provide appropriate solutions to organisations, employees and society who are facing problems such as centralisation of authority, low motivation, stress, environmental issues, behavioural problems, health problem, work-like balance, accountability, etc.

Henry Fayol’s Administrative Theory of Management :

After conducting many experiments and observations in organisation, Henry Fayol introduced 14 principles of management. He was a French mining engineer, who became Chief Managing Director. On account of his contribution I in management, he is called as “Father of Modem Management.” His 14 principles of management are as follows :

(1) Principle of Division of Work : This principle suggests that entire work, job or task should be divided into different parts such as technical, financial, commercial, accounting management and security operations. Each part should be assigned to different groups of employees according to their qualifications, qualities, capabilities and experience. It gives benefits of specialisation and improves efficiency.

(2) Principle of Authority and Responsibility : According to this principle, manager should be given authority to get the work done from his subordinates. Authority should always go with corresponding responsibility. Manager should have proper authority to take managerial decisions and also responsibility to complete the job in time.

(3) Principle of Discipline : This principle states that strict observance and respect for general rules, regulations, agreements, etc., at every level of organisation are essential for smooth working and achieving organisational goals.

(4) Principle of Unity of Command : As per this principle every employee should receive orders and instructions from only one superior (boss) and he should be accountable to same. If he receives orders from more than one superior, he will get confused.

(5) Principle of Unity of Direction : According to this principle, a group of employees working on similar activities should have common objectivesand must work under one head (senior) i.e. there should be one head and one plan. It leads to effective co-ordination of individual efforts and energies.

(6) Principle of Subordination of Individual Interest to Organisational Interest : According to this principle, organisational interest must be j given greater importance than individual interest. While taking the decision, the manager must consider the interest of whole group (or organisation) rather than the interest of a single
employee. This is because individuals will be able to achieve their objectives only when organisation makes profit.

(7) Principle of Centralisation : According to this principle, a company must not be completely centralised or decentralised. There must be a combination or proper balance between centralisation and decentralisation, depending upon the nature and size of the organisation. It leads to smooth functioning of am organisation.

(8) Principle of Remuneration : This principle states that the employees in the organisation must be paid just and fair remuneration to keep them satisfied financially and to retain them for long span of time. It boosts the morale of employees which results in greater efficiency and productivity.

(9) Principle of Scalar Chain : According to this principle, orders, information, instructions, messages, explanations, etc. must be passed \ through every key of the chain without skipping any one key in between. This is called Scalar Chain which is time consuming. However, in the case of emergency and to take quick decision, a short cut (Gang Plank) in the chain is permitted.
It means direct communication between the authorities working at same level of management.

Principle of scalar chain :

In the above diagram, the communication between ‘D’ and ‘G’ thorugh C, B, A, E and F is called Scalar Chain and direct communication between ‘D’ and ‘G’ without taking help of any one is called Gang Plank.

(10) Principle of Order : This principle suggests that in every organisation there should be proper, systematic and orderly arrangement of men and materials. The main purpose of this principle is that there should not be a wastage of time and energy for searching or finding out any material or any employee.

(11) Principle of Equity : This principle states that management should be fair and friendly while allocating the work, delegating authority or deciding monetary term. The management should not make any discrimination among the employees. Employees working on the same level but in different departments should be paid equal remuneration. It helps to boost the morale of employees and develops a sense of belongingness among the employees.

(12) Principle of Stability of Tenure : This principle suggests that the management should guarantee stability of tenure to the employees. This minimises the turnover ratio of talented employees and wastage of resources.

(13) Principle of Initiative : This principle states that managers should give freedom to the subordinates to come up with new ideas. The | initiative taken by the employee should be welcomed by the manager with thorough discussion on those ideas. This ultimately leads to healthy organisational culture.

(14) Principle of Esprit de corpse (Team work) : Esprit de corpse implies Union is Strength.
According to this principle, leader or manager should create the feeling of team spirit and understanding among the employees. It integrates and coordinates the individual and group efforts to achieve goals.

Fredrick Winslow Taylor’s Scientific Management Theory :

F. W. Taylor was an American mechanical engineer. He experimented in the Midvale Steel j workers in USA in early 20th century. He formulated and developed his observations and experiments based on scientific data. His approach towards management is called the scientific management.

On account of his scientific approach towards management, he is called Father of Scientific Management. He was of the opinion that problems must be solved by scientific techniques rather than the rule of thumb and trial and error approach.

Principles of scientific management : F. W. Taylor’s principles of scientific management are summarised as follows :

(1) Science, Not Rule of Thumb : This principle states that to increase organisational efficiency, manager should not use personal judgements but should use the scientific method to determine every activity performed by the employee. This principle related with the selection of the best way to perform a job after scientific analysis and not be rule of thumb or trial and error methods. Taylor insisted upon scientific plan even for small production activity like loading iron sheets into box carts.

(2) Harmony, Not Discord : This principle states that in order to achieve goals of the organisation, there should be harmony and proper co-ordination between the employees and management. This helps in minimising conflicts between them. Perfect understanding between them will also be helpful in creating healthy work environment. At the same time, organisation should pay attention to maximum prosperity of employees.

(3) Mental revolution : This principle focuses attention on the complete change in the attitude of the management and employees towards each other. This change will help in achieving goals, increase in productivity and sense of belongingness among the employees.

(4) Co-operation, not Individualism : This principle states that in every organisation there should be mutual cooperation between management and employees. Trust, team spirit, co-operation, etc. are essential to avoid internal competition and to create healthy working environment. Employees’ suggestions, new and innovative ideas should be appreciated and considered by the management in decision making process and treat them as an internal part of the organisation in all respects. At the same time, employees should not use actions like going on strike and making unacceptable demands from the management.

(5) Division of Responsibility : This principle states that while dividing the work between the management and employees, there should be corresponding division of responsibility as well.
Major planning should be done by the top and middle level of management authorities and these plans should be executed by the employees. It helps the management and the employees to perform their task in better manner.

(6) Development of employer and employees , for greater efficiency and maximum prosperity This principle states that profitability and best performance in any organisation depends upon the skill, intelligence and capabilities of its employees. This can only be possible by providing training and development programmes to the employees at regular interval. Each and every employee should be given proper opportunity to attain efficiency and maximum prosperity.

Techniques of Scientific Management :
The techniques of scientific management are explained below :

(1) Work Study : Before allotting the work among the available employees, systematic work study should be done by the management. This study includes an organised, systematic and critical assessment of the different functions or activities.

Work study based on different techniques are :

(a) Time Study : It is a method in which the management observes the employees on the work and determines the precise time required to complete the work. This technique is used to fix standard time needed to complete a specific task under given conditions. Manager can measure the efficiency of employees and control the cost of j work.

(b) Method Study : Under this method, management identifies and accepts best method of doing a job for best quality and cost effectiveness. It helps in reducing the wastage of time, raw material and improve the utility of all resources as per objectives determined in advance.

(c) Motion Study : Under this method, the close study of the movement of employee and machine in completing a particular task or job is done to eliminate unnecessary movements and find out best method. It improves efficiency and productivity of the employees. This method is useful to know whether some elements of job can be eliminated or their sequence can be changed for better job performance.

(d) Fatigue Study : Usually, long working hours with insufficient breaks, heavy working tools, target pressure and poor working conditions lead to fatigue. It reduces efficiency and creates adverse effect on health. Management must take certain measures to reduce the level of fatigue.

(2) Standardisation of Tools and Equipment : On the basis of experiments conducted at work j place, Taylor recommended to provide standard tools and equipment, standard working environment and can suggest standard methods of production to reduce wastage and spoilage of materials, cost of production, fatigue. It ultimately helps to improve quality of work.

(3) Scientific Task Setting : The technique of scientific task setting is useful to restrain the employees from doing the work much below their strength and capacity. This technique helps the employees to complete the job according to the standards given. The management can keep control on the optimum use of available labour.

(4) Scientific Selection and Training : According to this technique as per requirement, job specifications need to be fixed and employees are selected as per predetermined standard in an impartial way. Proper training need to be arranged for employees to increase their efficiency.

(5) Functional Organisation : Taylor suggests that planning should be separated from implementation. He further suggested that planning of the work and actual work should be done by different sets of people. He recommended eight foremen to control various parts of the production.

(A) At planning level :

• Route clerk : tells the employees how work moves from one machine to other.
• Instruction clerk : records instruction to complete the work.
• Time and cost clerk : determines time in which work should be completed and workout the cost.
• Discipline : ensures that workers are working as per factory rules.

(B) At implementation level :

1. Gang boss : Actually gets the work done.
2. Speed boss : Ensures that work is completed in specified time.
3. Repair boss : Handles security and maintenance of mechanism.
4. Inspector : Ensure that the work is done as per specified standards.

(6) Differential Piece – Rate Wage Plan : Under this technique, management fix the standard quantity of production. The employees who produce more than standard output are to be paid remuneration at higher rates and those who produce less than standard output are to be paid remuneration at lower rate. This technique is useful to encourage employees to attain higher standard performance to earn wages at higher scale.

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 12th Science Chemistry Notes Chapter 15 Introduction to Polymer Chemistry students can recall all the concepts quickly.

Maharashtra State Board 12th Chemistry Notes Chapter 15 Introduction to Polymer Chemistry

Classification of Polymers-

1. Based on source or origin
2. Based on structure
3. Based on intermolecular forces
4. Based on the mode of polymerization
5. No. of monomers
6. Biodegradability

Based on source or origin:

• Natural Jute, linen
• Synthetic Nylon, terylene
• Semisynthetic Acetate, rayon

Based on structure:

• Linear Polyethene
• Branched-chain Polypropylene
• Cross-linked vulcanized rubber melamine

Based on intermolecular forces:

• Elastomers Neoprene
• Fibres Nylon-6 polyesters
• Thermoplastic PVC, Polystyrene
• Thermosetting Bakelite

Based on mode of polymerization:

• Addition Polyvinyl chloride
• Condensation Nylon polyester dacron
• Ring-opening Nylon-6

No. of monomers:

• Homopolymers Polyacrylonitrile
• Copolymers Buna-S, Buna-N

Biodegradability:

• Biodegradable PHBV
• Non- biodegradable Bakelite, Nylon

Natural rubber: It is a linear polymer of isoprene (2-methyl-1, 3-butadiene), Cis isomer, exhibits elastic property.

Vulcanization of rubber: The effect of vulcanization enhances the properties like stiffness elasticity, toughness etc. of natural rubber
Natural rubber +1-3% sulphur → Rubber is very soft
Natural rubber + 20-30% sulphur → Rubber is hard.

Polyethene:

(1) LDP (Low-density polyethylene)

(2) HDP (High density polyethylene)

(3) Teflon :

(4) Polyacrylonitrile :

(5) Condensation polymerization. (Polyamide, polyester fibres)

Example : Nylon-6, Nylon-66, Terylene.

(6) Preparation of bakelite :
Formaldehyde + Phenol → Novolac → Bakelite
Other polymers of formaldehyde

1. with urea (NH₂CONH₂) → Moulded plastic
2. with melamine: formaldehyde + melamine → monomer formaldehyde melamine polymer

(7) Preparation of synthetic rubber :

• Buna-S (SBR) Styrene-butadiene rubber
  Styrene + 1, 3-butadiene → Buna-S
• Neoprene rubber
  

(8) Semisynthetic fiber:

(9) Biodegradable polymers :

PHBV (polyhydroxy butyrate-CO-β hydroxy valerate)
3-Hydroxy butanoic acid + 3 Hydroxy pentanoic acid PHBV (ester linkage)

Nylon-2-nylon-6
Glycine + amino caproic acid → Nylon -2-nylon-6

(10) Commercially important polymers :

• Perspex/acrylic glass
• Buna N
• PVC
• Polyacryl amide
• Urea-formaldehyde resin
• Glyptal
• Polycarbonate
• Thermocol.

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 11 Enhancement of Food Production students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 11 Enhancement of Food Production

Improvement in Food Production-

• Food: It is defined as any solid or liquid substance, which is swallowed, digested and assimilated in the body to keep us well.
• It is an organic, energy-rich, non-poisonous, edible, and nourishing substance.
• Importance of food: It gives us energy for all body activities. It keeps us alive, strong and healthy.

Plant breeding-

1. Plant breeding involves the improvement or purposeful manipulation in the heredity of crops and the production of new superior varieties of crops.
2. It involves genetic alteration of plants to increase their value and utility.
3. Objectives of plant breeding : Some objectives of plant breeding are common (as given below) and some vary according to type and use of the plant.

• To increase crop yield.
• To improve quality of produce.
• To increase tolerance to environmental stresses.
• To develop varieties of plants resistant to pathogens and insect pest.
• To alter the lifespan.

4. Different methods of plant breeding : Introduction, selection, hybridization, mutation breeding, polyploidy breeding, tissue culture, r-DNA technology, SCP (Single cell protein).

5. The present day crops are the result of domestication and acclimatization.
A. Hybridization and its technique :

• Hybridization is an effective means of combining the desirable characters of two or more varieties.
• New genetic combinations can be created by hybridization.
• It exploits and utilizes hybrid-vigour.

4. Types of Hybridization :

• Intravarietal (between plants of same variety)
• Intervarietal (between two varieties of the same species)
• Interspecific (between two species of the same genus)
• Intergeneric (between two genera of the same family)
• Wide/distant crosses : Crosses between distantly related parental plants. Interspecific and intergeneric hybrids are rare to occur in the nature.

5. The main steps of the plant breeding program (Hybridization) :

(1) Collection of variability :

• Germplasm collection : The entire collection having all the diverse alleles (i.e. variations) of all genes in a given crop.
• Germplasm conservation :
  • In situ conservation : Done with the help of forests and Natural Reserves.
  • Ex situ conservation : Done through botanical gardens, seed banks, etc.

(2) Evaluation and selection of parents
(3) Hybridization
(4) Selection and testing of superior recombinants
(5) Testing, release and commercialization of new cultivars

6. Green revolution :

• Green revolution is the development of high- yielding improved varieties of wheat and rice through techniques of plant breeding, in the decade from 1961, which helped the farmers to attain record production of agricultural crops in our country.
• Basic elements for Green revolution : The use of seeds of improved varieties of crops for cultivation, expansion of land for cultivation (farm land), optimum use of pesticides and fertilizers, multiple cropping system, modern farm machinery and proper irrigation system.
• Dr. Norman E. Borlaug was awarded the Nobel prize for developing the semi-dwarf varieties of wheat at international centre for wheat and maize.

Steps of hybridization

Germplasm collection:

• Evaluation and selection of parents with different qualities
• Obtaining pure lines by selfing of selected parents for three to four generations
• Identification of parents as male parent (donor) and female parent (recurrent)
• Collection of pollen grains from the flowers of male parent
• Emasculation of flowers of the female parent before anthesis
• Artificial cross (dusting of pollen grains collected from male parent on the stigma of emasculated flowers)
• Bagging, tagging of the emasculated flower of female parent
• Development of fruits and F₁ seeds
• Selection and testing of F₁ hybrid for combination of desirable characters
• Field trials for yield (productivity)
• Testing and the release of variety

7. Indian Hybrid Crops :

(1) Wheat and Rice :

• Hybrid wheat varieties in India : Sonalika and Kalyan Sona
• Semi-dwarf rice varieties in India : Jaya, Padma and Ratna
• Semi-dwarf rice varieties were developed from IR-8 (International Rice Research Institute) and Taichung native-I (from Taiwan) and introduced in India.

(2) Sugar cane :

• Saccharum barberi : Native of North India and it has poor yield and sugar content.
• S. officinarum : Grown in South India, has thicker stem and high sugar contents, but it does not grow well in North India.
• Hybrid varieties developed by crossing these two species have desirable combinations of characters like high sugar content, thicker stem and the ability to grow in North India.
• Sugar cane varieties developed at Coimbatore, Tamil Nadu : CO-419, 421, 453

(3) Millets : Hybrid maize (Ganga-3), Jowar (CO-12) and Bajra (Niphad) : High yielding and resistant to water stress.

8. Plant Breeding for Disease Resistance :

• Its objective is to develop varieties that are resistant to plant pathogens.
• It is carried out by hybridization process.
• Some of the plant diseases are as follows.
  

  Plant pathogens	Diseases
  Viruses	Tobacco mosaic disease Chilli mosaic disease
  Fungi	Brown rust of wheat Late blight of potato Red rot of sugar cane Smut of wheat
  Bacteria	Black rot of crucifers

• Disease resistant varieties of different crops :
  

  Disease resistant varieties	Diseases
  Pusa sadabahar of chilli	Chilli mosaic virus, Tobacco mosaic virus and leaf curl
  Pusa shubhra of cauliflower	Black rot and curl blight black rot
  Himgiri variety of wheat	Hill bunt Leaf and stripe rusy
  Pusa swarnim of Brassica	White rust

B. Mutation Breeding :

• Mutation : It is a sudden heritable change in the genotype, caused naturally.
• Natural (physical) mutagens : High temperature, high concentration of C02, X-rays, UV rays.
• Chemical mutagens : Nitrous acid, EMS (Ethyl – Methyl – Sulphonate), Mustard gas, Colchicine, etc.
• Effects of mutagens : Gene mutations and chromosomal aberrations.
• Seedlings or seeds are irradiated by Cobalt 60 or they are exposed to UV bulbs, X-ray machines, etc. The treated seedlings are then screened for resistance to diseases/ pests, high yield, etc.

Mutant varieties :

• Rice : Jagannath
• Wheat : NP 836 (rust resistant)
• Cotton : Indore-2 (resistant to bollworm)
• Cabbage : Regina-II (resistant to bacterial rot), etc.

C. Plant Breeding for Developing a Resistance to Insect Pest :

1. Resistance due to morphological characters :

• Hairy leaves in cotton : Vector resistance from jassids.
• Hairy leaves in wheat : Vector resistance from cereal leaf beetle.
• Solid stem in wheat : Resistance to stem borers.

2. Resistance due to biochemical characters :

• The high aspartic acid and low nitrogen and sugar content in maize : Resistance against stem borers.
• The nectar-less cotton having smooth leaves : Resistance against bollworms.

3. Some pest resistant varieties:

Insect resistant varieties of various crops	Insect pests
Pusa Sawani, Pusa A-4 of Okra (Bhindi)	Fruit and shoot borer
Pusa Gaurav of Brassica	Aphids
Pusa Sem 2 and Pusa Sem 3 of Flat bean	Jassids, aphids and fruit borers

Tissue culture

1. Tissue culture : It is growing isolated cells, tissues, organs ‘in vitro’ on a solid or liquid nutrient medium, under aseptic, controlled conditions of light, humidity and temperature, for achieving different objectives.
2. Explant : The part of plant used in tissue culture.
3. Totipotency : An inherent ability of living plant cell to grow, divide, redivide and give rise to a whole plant.
4. Haberlandt (1902) : He gave concept of in vitro cell culture (plant morphogenesis).
5. The plant tissue culture medium : It consists of all essential minerals, sources for carbohydrates, proteins and fats, water, growth hormones, vitamins and agar (for callus culture).
6. The most preferred medium for tissue culture : MS (Murashige and Skoog) medium.

7. Types of tissue culture :

• Based on the nature of explant : Cell culture, organ culture and embryo culture.
• Based on the type of in vitro growth : Callus culture (solid medium is used) and Suspension culture (liquid medium is used).

8. Requirements of tissue culture :

(1) Maintenance of aseptic conditions :

• Sterilization of glassware : It is carried out using detergents, hot air oven.
• Sterilization of nutrient medium : It is done by using autoclave.
• Sterilization of explant : It is carried out by treatment of 20% ethyl alcohol and 0.1% HgCl₂.
• Sterilization of inoculation chamber (Laminar air flow) : It is carried out by using UV ray tube for 1 hour before performing actual inoculation of explant on the sterilized nutrient medium.

(2) Temperature : 18 °C to 20 °C
(3) pH of nutrient medium : 5 to 5.8
(4) Aeration (particularly for suspension culture)

9. Steps in tissue culture : They are as given in the chart.

• Cleaning and sterilization of glassware and instruments in an autoclave or oven
• Preparation of defined nutrient medium . (MS medium)
• Sterilization of nutritive medium in an autoclave
• (For 20 minutes under constant pressure of 15/lb/inch²)
• Isolation and surface sterilization of explant
• Inoculation of the explant in the culture flask containing sterilized nutrient medium.
  (Inoculation is done in the laminar air flow cabinet unit) Incubation of the inoculated explant
  (cells of explant divide and give rise to callus, within 2-3 weeks)
• Sub culturing of the callus (Division of callus into 3-4 parts which are transferred to fresh culture medium)
• Organogenesis (Initiation of rooting and shooting)
• Plantlet formation
• Hardening of plantlets (Plantlets are transferred to polythene bags containing sterilized soil and kept at low light and high humid conditions for appropriate time period)
• Hardened plantlets are transferred to field

10. Sub culturing : Both the callus and suspension cultures die in due course of time. Therefore, sub culturing is necessary for continuation of the technique. In this a part of callus or suspension culture is transferred to fresh medium.

11. Micropropagation (Clonal Propagation) :

1. It is a type of tissue culture technique by which large number of plants are regenerated using organogenesis.

2. It is used in commercial production of plants like orchids, Chrysanthemum, Eucalyptus, banana, grapes, citrus, etc.

3. Advantages of micropropagation :

• Rapid multiplication of large number of plants within a short period and from a small space.
• Plants are obtained throughout the year, independent of seasons.
• Desirable characters (genotype) and desired sex of superior variety can be maintained for several generations.
• Conservation of rare plant and endangered species.
• Somatic hybrids (cybrids) can be used to develop new variety in short time span.
• High yielding varieties of banana like Shrimati, Basarai and G – 9 are used in Maharashtra.

12. Applications of tissue culture :

• Production of disease free plants and haploid plantlets.
• Production of stress resistant plants, micropropagation.
• Protoplast culture.
• Production of secondary metabolites.
• Culture of rare plants.
• Somaclonal variations.
• Application of tissue culture in forestry, agriculture, horticulture, genetic engineering and physiology.

Single cell protein (SCP)-

1. Conventional method to increase food yield : Use of different methods of crop improvement, biofertilizers, biopesticides, chemical fertilizers and high yielding varieties.
2. Nonconventional methods to increase the
food yield : Use of SCP .
3. , SCP is required to meet growing demand for
protein and to avoid protein malnutrition.
4. Single cell protein : It is a crude or a refined edible protein, extracted from pure microbial cultures or from dead or dried cell biomass.
5. Substrates used for the production of SCP : Wood shavings, sawdust, corn cobs, paraffin, N-alkanes, sugar cane molasses, human and animal wastes.
6. The microorganisms used for the production of SCP :

• Fungi : Aspergillus niger, Trichoderma viride
• Yeast : Saccharomyces cerevisiae, Candida utilis
• Algae : Spirulinaspp, Chlorella pyrenoidosa
• Bacteria : Methylophilusmethylotrophus, Bacillus megasterium

7. Advantages of Single Cell Protein :

• Microbes multiply fast. Hence, a large quantity of biomass can be produced in a short duration.
• The microbes can be easily genetically modified to vary the amino acid composition.
• SCP is a rich source of proteins (43% to 85% WAV basis), vitamins, amino acids, minerals and crude fibres.
• As waste materials are used as a substrate for SCP there is less pollution.

i. e. SCP can be used as fodder for achieving fattening of calves, pigs, in breeding fish, in poultry and cattle farmimg.

Biofortification-

1. Biofortification is a method of developing crops for having higher quantity and quality of vitamins, minerals and fats, to overcome problem of malnutrition.
2. Objectives of biofortification :

• Improvement in protein content and quality
• Improvement in oil content and quality
• Improvement in vitamin content
• Improvement in micronutrient content and quality

3. Methods of development of biofortified varieties : Conventional selective – breeding practices and r-DNA technology.

4. Some examples of biofortification :

• Fortified Maize (Twice the amount of amino acids – lysine and tryptophan)
• Wheat – Atlas 66 (High protein content)
• Rice (Has 5 times more iron)
• Carrot and spinach (Enriched with vitamin A and minerals)
• Bittergourd, tomato (Enriched with vitamin C enriched, developed by IARI)
• Animal husbandry-

1. Animal husbandry is an agricultural practice of breeding and raising livestock.
2. It deals with care and breeding of livestock like buffaloes, cows, pigs, horses, cattle, sheep, camels, goats, etc. which are useful to : humans.
3. Products obtained from animals : Milk, eggs, meat, wool, honey, silk, etc.
4. The production can be increased by –

• Effective management procedures
• New technologies in various farm systems to j improve quality and productivity
• Use of industrial principles of production processing and marketing

5. Management of farms includes selection of high yielding breeds, taking care of food requirements, supply of adequate nutritional sources, cleanliness of the environment and maintenance of health.

6. Management of farm animals includes veterinary supervision, vaccination, high yielding cross breed development, production and preservation of products, distribution and marketing.

A. Animal breeding :

1. Aims of animal breeding :

(1) To increase the yield of animals.
(2) To improve the desirable qualities of the products.
(3) To develop breeds with desirable characters.

2. Breed : A group of animals related by descent and similar in most characters like general appearance, features, size, configuration, etc.

3. Types of breeding :

(1) Inbreeding : Mating of two closely related individuals within the same breed for 4 to 6 generations.
(2) Outbreeding : Breeding of unrelated animals. It is of following types :

• Outcrossing : Mating of animals within the same breed, but having no common ancestors on either side of mating partners up to 4-6 generations is called outcrossing. [Mote : Outcrossing is not same as interspecific hybridization. ]
• Cross-breeding : Cross-breeding is a practice in which superior males of one breed are mated with superior females of another breed.
• Interspecific hybridization : Mating between male and female animals of two different related species, e.g., interspecific hybridization between horse and donkey produces a mule.

4. Artificial insemination : Used for controlled breeding experiments. Semen from the superior male is collected and injected into the genital tract of the female.

5. Multiple Ovulation Embryo Transfer (MOET) : MOET provides chances of successful production of hybrids.

B. Dairy farm management:

1. Dairy industry: It involves production, processing, marketing and distribution of milk and various milk products. Cow dung, manure, fuel cakes and gobar gas (for cooking and lighting) are sources of additional income.
2.  Breeds of cows :
   • Indian breeds of cows : Sahiwal, Sindhi, Gir”
   • Exotic breeds of cows : Jersey, Brown Swiss, Holstein.
3.  Breeds of buffaloes in India : Jaffarabadi, Mehsana, Murrah, Nagpuri, Nlli, Surati.
4. Cattle feed : Silage, oilcakes, minerals, vitamins and salts.
5. The cattle shed : It must be clean, spacious with adequate facilities for feeding, watering and lighting.
6. Cleanliness and hygiene of the cattle and handlers is important during milking, storage and transport of milk and milk products.
7. Mechanization of these reduces the chance of direct contact with the product.
8. Daily visit of veterinary doctor to dairy farm is mandatory to diagnose health problems, diseases and for their rectification.

C. Poultry farm management:

1. Poultry : It includes chicken, ducks, turkey, and fowls which are domesticated for their eggs and meat.
2. Allied professions to poultry : Processing of eggs and meat, marketing of poultry products, compounding and sale of poultry feed, poultry equipment, pharmaceuticals, feed additives, etc.
3. Requirements for poultry farm Management:
Selection of proper and disease free breed, suitable and safe farm condition, proper feed and water, hygiene and health care.

4. Poultry breeds (On the basis of their origin) :

• American breeds : Plymouth Rock, New Hampshire, Rhode Island Red
• Asiatic breeds : Brahma, Cochin and Langshan
• Mediterranean breeds : Leg horn, Minorca
• English breed : Australorp
• Indian breeds : Chittagong, Aseel, Brahma and Kadaknath.

5. Best layer (for eggs) : Leghorn.
6. Best broilers (for meat) : Plymouth rock, Rhode Island Red, Aseel, Brahma and Kadaknath.
7. Management of layers : It involves purchase of high yielding chicken, well-ventilated farms, proper feed, debeaking, lighting, waterer, sanitation, culling and vaccination.
8. Management of broilers : It involves selection of breed, housing, temperature, ventilation, lighting, floor space and broiler feed.

9. Poultry diseases :

• Viral diseases : Ranikhet, Bronchitis, Avian influenza (bird flu), etc. Bird flu had serious impact on poultry farming and also caused infection to humans.
• Bacterial diseases : Pullorum, Cholera, Typhoid, TB, CRD (chronic respiratory disease), Enteritis, etc.
• Fungal diseases : Aspergillosis, Favus and Thrush.
• Parasitic diseases : Lice infection, round worm, caecal worm infections, etc.
• Protozoan diseases : Coccidiosis.

D. Apiculture or bee keeping :

• Apiculture is artificial rearing of the honey bees.
• Products obtained by apiculture : Honey, wax, pollen, bee venom and royal jelly.
• Honey bees are important pollinators for crop plants and fruit trees.
• Apis dorsata (Rock bee or wild bee), Apis melltfera (European bee), Apis indica (Indian bee), Apis Jlorea (Little bee) are the four commonly occurring species in India.
• Apis mellifera and Apis indica are the : suitable species for apiculture and hence Eire : called domesticated species.
• Equipment required for apiculture: It includes beehive boxes, comb foundation sheets, bee veil, smoker, bee brush, gloves, gumshoes, uncapping knife, swarm net, queen : excluder, overall hive tool, etc.
• Successful apicultures also requires familiarity with the habits of bees, selection of suitable location, catching and hiving of swarms, management of hives during different seasons, handling and collection of honey, bee wax and other products, periodic inspection for cleanliness of hive boxes, activity of bees and queen, condition of brood, provision of water.
• Pollination of variety of crop plants by honey bees increases the productivity of honey and crop.

E. Fishery:

• Catching, processing, fish farming and marketing of the fish and other edible aquatic organisms is called fishery.
• Some fishes, prawns, lobsters, oysters, mussels, crabs, etc. are commercially important varieties.
• Inland fishery, estuarine fishery and marine fishery are the three main types of fisheries.
• A long coastline of India of about 7500 km and 40 to 50 lakh acres of fresh water bodies together constitute fishery potential.
• Common fresh water fishes, Rohu, Catla, Mrigal, common carp, grass carp, silver carp, etc. while marine fishes such as Hilsa, Bombayduck, sardines, pomphrets, mackerel, etc. are important varieties of fish.
• Fish farming is another occupation related to fishery in which culturing of some varieties of fish is done. Monoculture and polyculture are two main methods of aquaculture.
• Maintenance of fish farm : It involves selection of suitable site, excavation of ponds, requirements of hatchery tank, nursery tank rearing tank, stocking tank or ponds, water source, manures, supplementary feed, etc.
• Fish farming or culturing of commercially important edible fishes is only possible in fresh water bodies.
• Fish spoilage is prevented by preservation methods such as chilling, freezing, freeze drying, sun-drying, salting, canning, etc.
• Fish oil, fish meal, fertilizers, fish guano fish glue and Isinglass are some of the by-products made from the fish.

F. Sericulture:

• Rearing and production of silkworm (Bombyx mori) for obtaining silk is sericulture.
• Types of silk fibres : Mulberry silk, Tussar silk and Eri silk. Best quality mulberry silk is produced by Bombyx mori.

G. Lac culture :

• Tacchardia lacca insect produces lac. Lac is the resinous substance produced by dermal glands of the female insect.
• Plants such as her, peepal, palas, kusum, babool, etc. form the feed of these insects.
• 85% of lac produced in the world is from India.
• Various articles such as bangles, toys, woodwork, polish inks, silvering of mirrors, etc. are produced from lac.
• Artificial inoculation of plants give better and regular supply of lac.

Microbes in human welfare-

1. Biotechnology : It is defined as applications of ‘Scientific and Engineering principles for the processing of materials by biological agents to provide goods and service to humans or for human welfare’.

2. Microbes in food preparation :

1. Lactobacilli : Dhokla
2. Leuconostoc and Streptococcus bacteria : Dosa and idlis.
3. Microbes as the source of food : e.g. SCR fleshy fruiting bodies of edible mushrooms and truffles (higher fungi).

Dairy Products :

• Curd : Lactobacillus acidophilus
• Yoghurt : Streptococcus thermophilus and Lactobacillus bulgaricus
• Buttermilk : It is the acidulated liquid left after churning of butter from curd.
• Cheese : The milk is coagulated with LAB. The curd formed is filtered to separate whey and the solid mass is then ripened with growth of mould that develops flavour in it.
  • ‘Roquefort cheese : Ripened by blue- green mold Penicillium roquefortii
  • Camembert cheese : Ripened by blue- green mold Penicillium camembertii
  • Swiss cheese : Ripened by Propionibacterium shermanii. The large holes in Swiss cheese are developed due to production of a large amount of CO₂

Role of Microbes in Industrial Production-

Useful products produced during fermentation : Alcoholic beverages, organic acids, vitamins, growth hormones, enzymes, antibiotics and other molecules of medical significance are produced.

Statins produced by yeast Monascus purpureus are blood cholesterol lowering agents. They are competitive inhibitors of the enzyme that catalyzes synthesis of cholesterol.

1. Production of alcoholic beverages :

• Alcoholic beverages are produced by fermentation : liquors like beer, Whisky and wine.
• Saccharomyces cerevisiae var. ellipsoidis (Brewer’s Yeast) is used for fermenting malted cereals and fruit juices to produce ethanol.
• The beverages produced without distillation : Wine and Beer
• The beverages produced with distillation : Whisky, brandy and rum

Traditional drinks :
a. Toddy : Made by fermenting the sugar sap extracted from palm plants and coconut palm.
b. Fenny : Made by fermenting fleshy pedicels of cashew fruits.

2. Production of organic acids :
Microbes are used in the production of a number of organic acids.

• Aspergillus niger – Citric acid
• Aspergillus niger – Gluconic acid
• Rhizopus arrhizus – Fumaric acid
• Acetobacter aceti – Acetic acid (vinegar)

3. Production of vitamins :

(1) Vitamins : Organic nitrogenous compounds capable of performing many life-sustaining functions inside our body.
(2) Examples of vitamins : Thiamine, riboflavin, pyridoxine, folic acid, pantothenic acid, biotin, vitamin B₁₂, ascorbic acid, beta-carotene (provitamin A) and ergosterol (provitamin D).
(3) Vitamins are manufactured by fermentation using different microbial sources :

• Vitamin B₂ – i. Neurospora gossypii
  ii. Eremothecium ashbyi
• Vitamin B₁₂ – Pseudomonas denitrificans
• Vitamin C – Aspergillus niger

4. Production of Antibiotics :

(1) Antibiotics are secondary metabolites produced in small amounts by certain microbes (like bacteria, fungi and few algae), which inhibit growth of other microbial pathogens.
(2) They are used in treatment of deadly diseases like plague, whooping cough, diphtheria, leprosy, etc.
(3) Some common antibiotics and their microbial sources are as follows :
(4) Different antibiotics produced from following microbes:

• Chloromycetin → Streptomyces venezuelae
• Erythromycin → Streptomyces erythreus
• Penicillin → Penicillium chrysogenum
• Streptomycin → Streptomyces griseus
• Griseofulvin → Penicillium griseofulvum
• Bacitracin → Bacillus lichenijormis
• Oxytetracycline, Terramycin → Streptomyces aurifaciens

5. Production of Enzymes :

(1) Enzymes : Enzymes are biocatalyst proteins which accelerate biochemical processes.
(2) Uses of enzymes in various industries :

• Textile industry : To improve the quality of the fabrics.
• Pulp and paper industry : Biomechanical pulping and bleaching.
• Food industry : Fermentation for the production of bread and drinks such as wine and beer,
• Detergent industry : Lipase is used because of superior cleaning properties, to increase the brightness and to remove oil stains.
• The extraction of substances like carotenoids and olive oil.
• Enzymes are also used in cosmetics, animal feed and agricultural industries, among others.
• Streptokinase has fibrinolytic effect. Hence, it is used as a ‘clot buster’ in blood vessels of heart patients.

(3) Examples of microbial sources from which enzymes are produced :

• Saccharomyces cerevisiae – Invertase
• Sclerotinia libertine, Aspergillus niger – Pectinase
• Candida lipolytica – Lipase
• Trichoderma konigii – Cellulase
• Streptococcus spp. – Streptokinase

6. Gibberellin production :

(1) Gibberellin is a growth hormone produced by higher plants and a fungus named Giberella.
(2) Practical applications :

• To induce parthenocarpy in apple, pear, etc.
• Used in breaking the dormancy of seed and also in inducing flowering in Long Day Plants (LDP).
• To enlarge the size of grape fruits.

Microbes in Sewage Treatment –

1. Composition of Sewage carried out in drainage :

• Sewage consists of about water (99.5% to 99.9%) and inorganic and organic matter (0.1 to 0.5%) in suspended and soluble form.
• Composition of sewage varies depending upon the type of waste discharged into water from different industries.
• It includes human excreta, household waste, dissolved organic matter and even pathogenic microbes, discharged water from hospital waste, slaughter house waste, animal dung, discharge from industriad waste (contains toxic dissolved organic and inorganic chemicals), tannery, pharmaceutical waste, etc. also add to sewage.
• It contains bacteria from soil and pathogenic microorganisms (bacteria, viruses and protozoa) causing dysentery, cholera, typhoid, polio and infectious hepatitis and soil bacteria.
• Bacteria in sewage include coliforms, fecal Streptococci, anaerobic spore forming Bacilli and other types originating in the intestinal tract of humans.

2. Sewage treatment process includes four basic steps:

• Prelinfinary Treatment: It Includes Screening and Grit Chamber.
• Primary treatment (physical treatment) : It involves treatment of sewage in primary sedimentation tanks.
• Secondary treatment (biological treatment): It includes treatment of sewage in aeration tanks.
• Tertiary treatment : It involves passage of sewage water through settling tank and anaerobic sludge digesters.

Microbes in Energy Generation-

1. Biogas is a mixture of methane CH₄ (50-60%), CO₂ (30-40%), H₂S (0-3%) and other gases (CO, N₂, H₂) in traces.

2. Substrates used for biogas production : Cattle dung (most commonly used substrate, a rich source of cellulose from plants), plant wastes, animal wastes, domestic wastes, agriculture waste, municipal wastes, forestry wastes, etc.

3. Biogas Production :

• Most commonly used models of biogas plants are developed by KVIC (Khadi and Village Industries Commission) and IARI (Indian Agricultural Research Institute).
• A typical biogas plant consists of digester and gas holder.
• Anaerobic digestion involves three processes : Hydrolysis or solublization, acidogenesis and methanogenesis.

4. Benefits of biogas :

• Biogas is a cheap, safe and renewable source of energy.
• It can be easily generated, stored and transported.
• It can be used for domestic lighting, cooking, street lighting as well as small scale industries.
• It burns with blue flame and without smoke.
• It helps to improve sanitation of the surrounding.
• It is eco-friendly and does not cause pollution.
• Sludge which is left over is used as a fertilizer.

Role of Microbes as Biocontrol Agents-

1. Biocontrol or biological control : It is the natural method of eliminating and controlling insects, pests and other disease-causing agents by using their natural, biological enemies.

2. Biocontrol agents : Microbes (bacteria, fungi, viruses and protozoans) act as biocontrol agents in three ways : they cause the disease to the pest or compete or kill them.

3. Some examples of Microbial bio-control :

• Bacillus thuringiensis (Bt) : It is used to get rid of butterfly, caterpillars.
• Trichoderma species : Effective bio-control agents against soil borne fungal plant pathogens.

4. Microbial Pesticides and their host:

Host	Microbial pesticide
Caterpillars, Gypsy moth, ants, wasps, beetles	Viruses : Nucleopolyhedrovirus (NPV) Granulovirus (GV)
Caterpillars, cabbage worms, adult beetle	Bacteria : Bacillus thuringiensis (Bt) B. lentimorhus B. papilliae
Aphid crocci, A. unguiculata, mealy bugs, mites, white flies	Fungi : Beavueria bassiana Entomorphtora pallidaroseum Zoopthora radicans
Grasshoppers, caterpillars, crickets	Protozoans : Nosema locustae

5. Bioherbicides : They kill the weeds which compete with the main crop in the farm – land for water, space, minerals, light, air, etc. and also act as collateral hosts for several pathogens.
(1) Pathogenic fungi as mycoherbicides :

• Phytophthora palmivora – controls milk weed in orchards.
• Alternaria crassa – controls water hyacinth.
• Fusarium spp. – control most of the weeds.

(2) Bacterial pathogen as herbicides :

• Pseudomonas spp. – attacks several weeds
• Xanthomonas spp. – attacks several weeds
• Agrobacterium spp. – attacks several weeds

(3) Insects as herbicides :

•  Tyrea moth – controls the weed Senecio jacobeac
• Cactoblastis cactorum – controls cacti weeds.

Role of Microbes as Biofertilizers-

1. Fertilizers are the nutrients required for plant growth and increase the productivity of cultivated plants.
2. Types of fertilizers :

• Inorganic fertilizers : They are synthetic fertilizers consisting of mineral salts of NPK mixed in specific proportion. If used excessively, they cause pollution of soil, air and groundwater.
• Organic fertilizers : They are biological in origin and include farm yard manure (FYM), compost and green manure.

3. For better and sustainable agricultural production, organic farming is practised and biofertilizers are used.

4. Biofertilizers include bacterial, cyanobacteria and fungi :

• Bacterial biofertilizers : These include bacteria and cyanobacteria
• Fungal biofertilizers

5. Types of Biofertilizers on the basis of nature and function :

(1) N₂ fixing Biofertilizers :

• The nitrogen fixing microorganisms (diazotrophs) convert atmospheric nitrogen into nitrogenous compounds like nitrites and nitrates via ammonia.
• Symbiotic N₂ fixing microorganisms : e.g. Rhizobium, Frankia.
  These are mostly associated generally with roots of higher plants.
• Free-living or Non-Symbiotic N2 fixing microorganisms : e.g. Azotobacter, Clostridium, Beijerinkia, Klebsiella, etc.

(2) Phosphate solubilizing biofertilizers :

• These bacteria solubilize the insoluble inorganic phosphate compounds.
• e.g. Pseudomonas striata, Bacillus polymgxa, Agrobacterium, Microccocus, Aspergillus spp. etc.

(3) Compost making biofertilizers :

• In the composting process microorganisms break down organic matter into dark rich compost or humus.
• Microorganisms found in active compost: Bacteria, fungi, actinobacteria, protozoa and rotifers.

6. Cyanobacteria as biofertilizers :

• They may be free-living or symbiotic, heterocystous or non-heterocystous forms.
• Free living cyanobacteria : e.g. Anabaena, Nostoc, Plectonema, Oscillatoria.
• Symbiotic cyanobacteria associated with lichens : Anabaena, Nostoc and Tolypothrix.
• Symbiotic cyanobacteria associated with plants Azolla and Cycas : Anabaena.

7. Fungal biofertilizers :

(1) Mycorrhiza is a fungus which forms symbiotic association with the rhizomes and root of higher plants occurring in thick humid forests.

(2) Two types of mycorrhizal :

• Ectomycorrhizae : Mycelium of these fungi form mantle on the surface of the roots.
• Endomycorrhizae : They grow in between and within the cortical cells of roots.

(3) Benefits of Mycorrhiza :

• Selective absorption of P Zn, Cu, Ca, N, Mn, Br and Fe.
• Enhance water uptake.
• Induce growth by secreting hormones.
• Offer protection to host plant from other microbes, by secreting antibiotics.

(4) Nowadays, mycorrhiza are classified into 8 different types : Ectomycorrhizae,

Endomycorrhizae, Ectendo mycorrhizae, Orchidaceous mycorrhizae, Ericoid mycorrhizae, Arbutoid mycorrhizae, Monotrapoid mycorrhizae and Ophioglossoid mycorrhizae.

8. Biofertilizer microorganisms :

• Rhizobia : Nitrogen fixing bacteria in root nodules of leguminous plants.
  e. g. R. leguminosarum is specific to pea and R. phaseoli is specific to beans.
• Azotobacter: Free living, nitrogen fixing bacterium associated with roots of grasses and certain plants.
• Azospirillum: Free living, aerobic nitrogen fixing bacterium associated with roots of corn, wheat and jowar.
• Anabaena : Filamentous nitrogen fixing cyanobacteria that forms symbiotic relationships with certain plants, such as the coralloid roots of Cycas and Anthoceros thallus. It has Heterocysts (Specialized colourless cells which are the sites for nitrogen fixation). It also fixes nitrogen in free living conditions.
• Azolla : A free-floating water fern. Anabaena present in the dorsal leaf lobe fixes nitrogen.

9. Benefits of Biofertilizers :

• Low cost and can be used by marginal farmers.
• Free from pollution hazards.
• Increase soil fertility.
• BGA secret growth promoting substances, organic acids, proteins and vitamins.
• Azotobacter supply nitrogen and antibiotics in the soil.
• Biofertilizers increase physico-chemical properties of soil-like texture, structure, pH, water holding capacity of soil by providing nutrients and organic matter.

Know the Scientist:

1. Dr. Norman E. Borlaug : Known as ‘Father of the Green Revolution’, ‘Agriculture’s greatest spokesperson’ and ‘The Man Who Saved a Billion Lives’.
A 1970 Nobel Laureate.
He saved millions of lives from famine in India, Mexico and the Middle East.

2. Dr. M. S. Swaminathan : Known as ‘Father of Green Revolution in India’.
He introduced and developed high-yielding varieties of wheat in India.
He is pioneer in mutation breeding in India.
He developed new varieties of wheat like Sarbati, Sonora and NP165.
He advocated environmentally sustainable agriculture, sustainable food security and the preservation of biodiversity.

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 6 Plant Water Relation students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 6 Plant Water Relation

Introduction-

1. Types of substances required by the plant from its surroundings

• Water
• Minerals
• Nutrients
• Food (for parasites)
• Gases from the atmosphere : (A) O₂ for respiration (B) CO₂ for photosynthesis

2. Water is absolutely necessary for all vital activities. Hence referred to as elixir of life.
3. Role of water :

• Major constituent of protoplasm (90-95%)
• Helps in maintaining the turgidity of cells and their shape.
• It is a transporting medium.
• Water affects productivity of plants.

Properties of water-

1. Important properties of water.

• Liquid form at room temperature.
• Best solvent for various solutes.
• Inert inorganic compound.
• Neutral pH (i.e. pH = 7) of pure water.
• High specific heat.
• High heat of vaporization.
• High heat of fusion.

2. Due to these properties water is best transporting medium, best medium for biochemical reactions and acts as a thermal buffer.
3. Hydrogen bonding occurs in liquid water which is mainly responsible for these properties.
4. Good adhesive and cohesive forces exist in water molecule.
5. Owing to high surface tension and these forces, it can rise in capillaries.
6. Water is a molecule that connects or is a link between physical factors and biological processes.

Water absorbing organ-

1. Root system – Chief organ of water and mineral absorption.
2. Terrestrial plants absorb liquid water from soil with root hairs while epiphytes like orchids, have special hygroscopic tissue velamen that absorbs water vapour from atmosphere.
3. Regions of root – four zones.
Root cap is situated at tip behind it is

• zone of meristematic region
• zone of elongation
• zone of absorption or root hair zone and
• zone of maturation.

4. In zone of absorption, thin, delicate, unicellular hair like extensions i.e. root hairs develop from epidermal cells.
5. Structure of root hair : It is cytoplasmic extension, tube like, colourless, unbranched and short lived (ephemeral) structure.
6. Root hair has large central vacuole, thin cytoplasm, plasma membrane and double layered wall of pectin and cellulose.
7. Freely permeable cell wall while selectively permeable plasma membrane.

Water available to roots for absorption-

1. Rhizosphere : Microenvironment surrounding the root, constitutes rhizosphere from which plants absorb water.
2. Soil is the main source of water for plants.
3. Water present in soil is in following forms namely :

• Gravitational water percolated deep in soil due to gravity.
• Hygroscopic water held tightly around soil particles, adsorbed or adhered water on fine particles.
• Combined water present as hydrated oxides of silicon, aluminium, etc.
• Capillary water present in the fine spaces or capillaries between soil particles.

4. Plants readily absorb capillary water from soil.

Absorption of water by roots from soil-

When water is absorbed by plant, all the three physical processes occur simultaneously at root hair.

1. Imbibition :

• Swelling up of hydrophilic colloidal substances.
• Water is adsorbed on the surface.
• Imbibant : Substance that adsorbs.
• Imbibate : Substance that gets imbibed.
• In root hair double layered cell wall of cellulose and pectin is imbibant.
• Water is tightly adsorbed on the surface till the equilibrium is reached.

2. Diffusion :

• Movement of ions/atoms/molecules of a substance from region of high concentration to that of their low concentration.
• Movement results due to kinetic energy.
• It takes place till equilibrium is reached.
• In root cell, diffusion occurs through freely permeable cell wall.
• Diffusion pressure created is directly proportional to number of diffusion particles.
• Pure water has more diffusion pressure (D.E) than solvent in solution.
  Diffusion results in diffusion pressure. D.ED. can be considered as thirst of cell, capacity which absorbs water from surrounding of adjacent cell.
• D.ED. (Diffusion Fressure Deficit = S.E (Suction Fressure)
• Difference in D.E of pure solvent (i.e. water) and solvent in solution is termed D.ED.
• D.ED. is capacity to absorb water from surrounding.
• Cell sap has less D.E than water around cell wall. Thus, water diffuses inside.
• It is significant in absorption of water and minerals, transport of food, exchange of gases and conduction of water upwards against gravity.

3. Osmosis :

•  A process by which water actually enters root hair (cell interior).
• Special type of diffusion.
• Involves movement of solvent through a semipermeable membrane.
• Cell sap inside the cell is concentrated (minerals, sugars) while solution outside cell is weaker. Hence solvent (water) from outside enters the cell passing through semipermeable plasma membrane.
• In root cell, at interphase of cell wall and plasma membrane, water enters by osmosis.
• Type of solutions based on concentration
  
• Two types of osmosis
  
• Turgor pressure (T.P.) : Pressure exerted by turgid cell sap on cell membrane and cell wall.
• Fully turgid cell has D.ED. = 0 (zero)
• Wall pressure (W.P.) : Cell wall exerts pressure on inner cell sap i.e. counterpressure. Hence T.P = W.P but it is in opposite direction.
• Osmotic pressure (O.P.) : Pressure exerted due to osmosis so as to stop entry of water (solvent) inside.
  • Pressure of solution in opposite direction.
  • To check entry of water (solvent molecules) inside cell.
• D.RD. (thirst of cell) demand or ability to gain water by cell = O.P – T.P and T.P = W.P
  ∴ D.ED. = O.P – W.P (Osmotic pressure minus wall pressure)
• In flaccid cell T.P is 0 (zero) . .D.RD. = O.E In turgid cell D.PD. is 0 (zero) ..T.R = O.R

Facilitated diffusion :

• Passive absorption of solutes (no expenditure of energy)
• Takes place with the help of carriers (special proteins – porins)
• Diffusion through cell membrane
• Lipid soluble components can easily pass but hydrophilic components need carrier.
• Requirement of concentration gradient for diffusion.

Membrane proteins – aquaporins and ion channels are sites of facilitated diffusion.

Water potential ( Ψ )-

• Free energy is needed to do the work and for movement of water, i.e. osmosis )
• Chemical potential : Free energy per molecule in a chemical system.
  Water potential : It is chemical potential of water – Unit bars / pascal (pa) / atmosphere D.RD. is now termed as water potential.
• Water potential of protoplasm is opposite in sign but equal to D.RD. i.e. negative value.
• Pure water has water potential zero. When some solute is added there is decrease in water potential (t//) i.e. negative.
• Flow of water is from less negative potential to more negative potential, i.e. from higher water potential to lower.
• In adjacent cells, plasmodesmata connections are concerned with movement of water.

Factors affecting water absorption :

• Types of water-presence of capillary water.
• Soil temperature-favourable range 20 to 30°C.
• Concentration of solutes in soil water – High solute concentration reduces rate of absorption.
• Soil aeration : If soil aeration is less then there is absorption.
• Rate of transpiration : With increase in transpiration, there is increase in absorption of water.

Plasmolysis-

1. Exosmosis that occurs in living cells upon placing in hypertonic (concentrated) solution is termed plasmolysis.

• Shrinkage of protoplasm
• Separation from cell wall forms a gap between cell wall
• Flaccid nature due to removal of water.

2. Turgor pressure (T.R) is zero in plasmolysed cell.
3. Deplasmolysis : When flaccid cell is kept in hypotonic solution endoosmosis takes place and thus it becomes turgid.
4. In fully turgid cell T.R = O.P and D.RD. is zero, (no absorption of water by cell)

Path of water across the root (i.e. from epiblema up to xylem in the stelar region)-

1. Root hair cell : Absorption of water takes place from rhizosphere by process of imbibition then diffusion and finally osmosis.

2. In turgid cells (root hair) due to absorption of water → Increased turgor pressure (T.P) and lowered D.PD. →adjacent cell (Cortical cell) → more D.PD. more osmotic pressure (O.R) → adjacent cell will take water from turgid root ha.i → root hair cell thus becomes flaccid → absorb water from soil.

3. A gradient of D.PD. or suction pressure (S.R) is formed from root epidermis till the region of cortical cells.

4. Movement of water is from root hair → epidermis → loosely arranged cortical cell → passage cells of endodermis → pericycle → protoxylem

5. Due to continuous absorption of water hydrostatic pressure is developed, i.e. root pressure → Helps in transfer and conduction further in xylem of root.

6. The movement of water from root hair to xylem takes place along two different pathways, viz. apoplast pathway and symplast pathway.

7. Pathway for water across roots:

8. Additional apoplast pathway :

• Direct pathway leading to xylem.
• Secondary roots originate at pericycle inside endodermis.
• Bypass endodermis having Casparian strip. Hence allow direct entry in vascular system.

9. In normal apoplast pathway, suberised layer forces shift to symplast in order to enter xylem.

10. Symplast pathway is transmembrane pathway through plasmodesmatal connections in living cells of cortex. The plasmodesmata interconnect the cytoplasm of cells forming cytoplasmic network called symplast.

Learn this as well :

• Vacuoles in the root cells are interconnected to form intercellular connections.
• Intervacuolar connections are formed between the cells.
• Cytoplasmic connections are towards the periphery of cell.
• Tonoplast, the membrane of vacuole is differentially permeable membrane which allows the passage of certain solutes but not all along with solvent.

Mechanism of absorption of water-

Translocation of water-

1. Ascent of sap : Transport of water along with dissolved minerals from root to aerial part against gravity is called translocation or ascent of sap.
2. Ascent of sap occurs through lumen of xylem tracheids and vessels. Physical forces and activity of living cells is required for ascent of sap. Complex tissue xylem as a path of water is proved by ringing experiment.
3. Root pressure theory (Vital theory) by J. Pristley :

• Living cells of root are responsible for translocation of water.
• Xylem sap exuding out from cut end of stem above the soil indicates existence of root pressure.
• As water is absorbed by root hair constantly and continuously, hydrostatic pressure is set in root cortical cells.
• Owing to this root pressure, water with dissolved minerals is pushed into xylem and also conducted upwards.
• Root pressure is an osmotic phenomenon, develops due to absorption of water.
• Oxygen, moisture, temperature and salt content of soil affect root pressure, Root pressure of +1 to +2 bars is sufficient to carry water upwards to 10 to 20 metres.

Objection to this theory :

• Not applicable to tall plants.
• Ascent of sap occurs even if root system is absent.
• Some tall plants have zero root pressure (Gymnosperms).
• Root pressure is absent in actively transpiring plants.
• Xylem sap shows negative hydrostatic pressure as it is under tension in normal condition.

4. Capillarity theory (Physical force theory) By Bohem :

• Physical forces and dead cells (xylem with lignified wall) are responsible for translocation.
• Water is raised to certain level due to capillarity.
• Capillarity is due to surface tension, cohesive and adhesive forces of water.
• Water conducting elements have lignified walls and are with lumen (xylem vessels and tracheids)
• Combined cohesive forces of water and adhesive forces of water with xylem wall form continuous water column.
• Owing to capillarity, water is conducted upwards against gravity.

Objection to capillarity theory :

• Continuous capillary tube is essential but tracheids have thickened, tapering closed end walls.
• Lower end of capillary tube not in direct contact with soil water.
• Tall trees show wide lumen in xylem vessels. Narrower the capillary tube, higher level of water column is raised.

5. Cohesion – Tension theory (Transpiration pull theory) By Dixon and Joly :

• Widely accepted theory of ascent of sap.
• Based on cohesion and adhesion with transpiration pull developed.
• Strong force of attraction of water molecules : Cohesive force
• Strong force of attraction of water molecules and lignified walls of xylem : Adhesive force
• Water loss is in the form of water vapour, mainly through stomata is transpiration.
• Owing to combined action of cohesive and adhesive forces, a continuous water column is maintained through xylem.
• Transpiration pull developed due to water loss in leaf vessels is transmitted downwards towards root.
• Water lost from stomata causes increased D.RD. of mesophyll cells which in turn takes water from xylem of leaf.
• A gradient of suction pressure or D.ED. is set in, due to transpiration, which causes tension or pull. Owing to this, water column is pulled upwards through xylem.
• It is passive pull of water against gravity which results in ascent of sap.

Objections to transpiration pull theory :

• Formation of gas bubbles due to temperature fluctuations may not keep water column continuous.
• Vessels as tabular structure are much evolved and efficient in conduction but this theory assumes trachieds are more efficient.
• If transpiration is checked due to some artificial means like application of Vaseline, then also ascent of sap occurs, (clogging of stomata due to application of Vaseline)
• Ascent of sap occurs in plants which are deciduous, (leaf fall)

Transport of mineral ions-

• Minerals are elements which play an important role in vital processes in metabolism. Thus they are essential elements for plants.
• Elements required in large amount, Macro elements : e.g. N, P C, H, O, etc.
• Elements are required in small amount, Micro elements : e.g. B, Cu, Mn, Co, etc.
• Soil is a chief source of minerals and they are absorbed in dissolved (ionic) form through root system.
• Minerals are absorbed by plants from their surrounding environment (atmosphere – C, H, O) and soil (inorganic materials).
• Absorption of minerals is independent of that of water.
• Minerals are transported with ascent of sap. Hence root is source and they get lodged at the required organ.
• Unloading of the transported material is by diffusion from veins and cells uptake them.
• Minerals can be remobilized inside plant body from older leaves to young leaves, e.g. R S, N, K, etc. But those parts of structural framework are not disturbed, e.g. Ca.
• Nitrogen in inorganic ion form and amino acids, amides in organic form are transported through xylem.
• Some exchange of material takes place between xylem and phloem.

Transport of food-

• Food is synthesised in chloroplast containing cells.
• Part of plant where food is synthesised is source (leaf) and where it is utilized is sink e.g. root.
• Translocation of food occurs from source to sink through phloem. The movement or transport of food from one part to other part is called translocation of food.
• Sieve tubes (phloem) and vessels (xylem) are ideal for vertical or longitudinal transport. Sieve tubes for downward transport.
• The lateral or horizontal translocation occurs through medullary rays (parenchyma) from phloem to pith or cortex.
• Food is translocated in soluble form sucrose along concentration gradient set from sink.
• Vertical translocation – (longitudinal transport)
  From leaves i.e. source to sink (root) in downward direction or growing point (stem) and seed germination, corm, bulbil germination in upward manner.
• Lateral translocation – occurs in root and stem.
  • Radial translocation from phloem to pith.
  • Tangential translocation from phloem to cortex.

• Phloem transport is bidirectional. Phloem sap has sucrose, and water with other sugar, amino acids and hormones.
• Mechanism of sugar transport through phloem – Mass Flow hypothesis or Munch’s Pressure flow theory is – most widely accepted concept.
• Other theories are diffusion, activated diffusion, electro osmosis, protoplasmic streaming.
• Ernst Munch theory : Glucose synthesised in photosynthesis which increases osmotic concentration of photosynthetic cell → Endo osmosis → water absorbed from adjacent cells and xylem → Turgidity of cell →Increased turgor pressure → sugar from photosynthetic cell forced into sieve tube → This is vein loading.
• Root cell (sink) → utilization of sugar → polymerisation of sugar to starch → osmotic concentration lowered. Exosmosis → hence water lost to adjacent cells → decrease in turgidity → Turgor pressure lowered → Turgor pressure gradient is set → Translocation of food passively along concentration gradient → This is vein unloading.
• Sugar is used at the sink or stored and excess water transported to xylem.

Objections of theory –

• Bidirectional flow is not explained.
• Pressure flow is a physical process.

Transpiration-

• From the constant absorption of water 5% is utilized and 95% surplus water is lost through aerial parts in the form of mainly water vapour.
• Guttation : Loss of water in liquid form (1%), occurs from water stomata or hydathode.
• Transpiration : Water lost in the form of water vapour mainly foliar transpiration.
• Types of Transpiration
  

Structure of stomatal apparatus-

• Stomatal apparatus has guard cells, stoma and accessory cells.
  
• The elliptical pores (opening – stoma) are bounded by two guard cells, either kidney shaped or dumbbell shaped cells.
• Guard cells are modified epidermal cells, nucleated cells with uneven thick wall – Inner wall thick and inelastic, outer wall is thin and elastic, with chloroplasts.
• Accessory cells/Subsidiary cells –
  Specialized epidermal cells that surround guard cells. They are reservoir of K⁺ ions.
• Opening and closing of stomata Is controlled by turgidity of guard cells.
• During daytime → Thrgld guard cells due to endoosmosls → ExertIon of T.P on outer thin wall → elastic wall stretch out → Thick walls pulled apart → stoma opens.
• During night-time → flaccid guard cells due to exosmosis → outer elastic wall relaxes → Inner thick walls pushed → stoma closes.
• Diurnal changes In osmotic potential are responsible for flaccidity and turgidity of guard cells.
• As per starch-sugar hypothesis → DurIng day time starch gets converted to sugar by enzyme phosphorylase → Increase osmotic potential → entry of water
  Reverse reaction during night → stoma close

As per proton pump theory — Transport of H⁺ and K⁺ ions

• During daytime – starch converted to malic acid → dissociation into malate and protons (H⁺) → H⁺ in subsidiary cells → K⁺ ions from subsidiary cells to guard cells → open stomata Potassium malate → Increase osmotic potential → endoosmosis (turgidity)
• At night → uptake of K⁺ and Cl^– ions is checked by abscissic acid – change In permeability, osmotic potential → Hypotonic guard cells → exosmosis → flaccid → stoma close

Advantages of Transpiration:

• Removal of excess water
• Helps In absorption of water
• Cooling effect
• Helps in gaseous exchange
• Maintains turgor of cells
• Ascent of sap

Disadvantage – Excessive transpiration causes wilting injury and that may lead to death of plant.

Transpiration : A necessary evil – (By Curtis)

• During daytime stomata remain open thus help in gaseous exchange – for respiration and photosynthesis
• Productivity is adversely affected if stomata remain closed
• When stomata are open transpiration cannot be avoided.

Know the scientists :
Scientists — Their theories/discoveries

1. B.S. Meyer – Coined the term Diffusion Pressure Deficit D.RD.
2. Atkins and – Osmotic absorption Pristley theory
3. Kramer and – Non-Osmotic absorption Thimann theory
4. J. Pristley – Root pressure theory
5. Bohem – Capillarity theory
6. Dixon and Joly – Cohesion Tension theory
7. Munch – Pressure flow theory
8. Steward – Starch-sugar interconversion theory
9. Levitt – Proton transport theory
10. Curtis – Transpiration as ‘a necessary evil’
11. S. Hales – Term root pressure

By going through these Maharashtra State Board 12th Science Chemistry Notes Chapter 14 Biomolecules students can recall all the concepts quickly.

Maharashtra State Board 12th Chemistry Notes Chapter 14 Biomolecules

Biomolecules: Biomolecules are lifeless molecules that combine in a specific manner to produce life or control biological reactions. Examples: They are carbohydrates, lipids, proteins, nucleic acids. They play
an important role in the functions of organisms.

Carbohydrates: Carbohydrates are optically active polyhydroxy aldehydes or ketones or compounds that can be hydrolyzed to polyhydroxy aldehydes or polyhydroxy ketones.

Classification of Carbohydrates:

Preparation of glucose: Glucose is prepared either from cane sugar or from starch.

Reactions:

Glucose can be represented by Fischer projection formulae and cyclic structure by Haworth projection formulae. Fructose is ketohexose and is made by the isomerization of glucose. It is laevorotatory and belongs to the D series. Fructose can be represented by Fischer projection formulae and cyclic structure by Haworth projection formulae. Disaccharides are sucrose, maltose, cellobiose, lactose, etc. Polysaccharides are starch, cellulose, glycogen, etc.

Proteins: Proteins are naturally occurring polymeric nitrogenous organic compounds containing 16% nitrogen and peptide linkages. Proteins are classified into fibrous proteins (keratin, hair, skin, nails) and globular proteins (hemoglobin, thyroglobulin). The structure of a protein can be studied at different levels called primary, secondary, tertiary, and quaternary. Proteins on hydrolysis give a mixture of α-amino acids .
Amino acids are classified into three types-basic, acidic, and neutral amino acids.
Peptide linkage (-CONH) in an amide formed between -COOH and -NH₂ group by elimination of water molecule.

Enzymes: Enzymes are biological catalysts for various chemical reactions in living organisms. Enzymes are required in small quantities. They act as catalysts and reduce the activation energy for a particular reaction. In many industrial processes, specific reactions are carried with the use of enzymes extracted from organisms.

Nucleic acids: Nucleic acids are esters of phosphoric acid with sugar. They control the synthesis of proteins and are also responsible for storing the genetic information of living organisms and passing the information from one generation to another.
Chromosomes contain two types of nucleic acids: Ribonucleic acid RNA and deoxyribonucleic acid DNA Nucleoside: A base-sugar unit
Nucleotide: A base-sugar-phosphoric acid unit. Nucleotides are monophosphates of nucleosides.

By going through these Maharashtra State Board 12th Science Chemistry Notes Chapter 13 Amines students can recall all the concepts quickly.

Maharashtra State Board 12th Chemistry Notes Chapter 13 Amines

Amines are nitrogen-containing organic compounds having basic character.

1. Classification of amines :

2. Methods of preparation and the reactions of primary amines :

3. Electrophilite aromatic substitution :

4. Preparation and reactions of arene Diazoniuni salts :

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 5 Origin and Evolution of Life students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 5 Origin and Evolution of Life

Origin of life (Protobiogenesis)-

1. Attributes of living organisms : Responsiveness, growth, metabolism, energy transformations and reproduction.
2. Various theories and hypotheses to propose origin of life :

Name of the theory	Characteristic point	What does the theory say?
Theory of special creation	Oldest theory. No scientific proof. Only religious beliefs.	All living organisms are created by a supernatural power.
Cosmozoic theory/Theory of Panspermia	NASA has reported fossils of bacteria­like organisms on a piece of Martian rock recovered from Antarctica.	Life descended to the earth from other planets in the form of cosmozoa/panspermia.
Theory of spontaneous generation (Abiogenesis)	Disproved by Louis Pasteur.	Life originated from non-living material
Theory of biogenesis	Explains only the continuity of life.	Living organisms produced from pre-existing living forms, by process called reproduction.

Chemical Evolution of Life (Self-assembly theory of origin of life)-

1. Theory of biochemical origin of life : Life originated on earth by combinations of several chemicals through constant chemical reactions over a long period of time.
Formulated by Haeckel, developed by Alexander I. Oparin (1924) and J. B. S. Haldane (1929).

2. The steps in the process of chemical evolution :

• Origin of Earth and Primitive atmosphere : Big-Bang theory of Georges Lemaitre (1931). Formation of reducing atmosphere.
• Formation of ammonia, water and methane : Formation of CH₄, NH₃, H₂O and H₂S.
• Formation of simple organic molecules : Formation of monosaccharides, amino acids, purines, pyrimidines, fatty acids, glycerol, etc. Formation of water bodies resulting into ‘hot dilute soup’ or ‘primitive broth’.
• Formation of complex organic molecules : Formation of complex organic molecules like polysaccharides, fats, proteins, nucleosides and nucleotides. Protoproteins → proteins.
  Formation of protein molecules : Landmark in the origin of life.
• Formation of Nucleic acids : Formation of Nucleotides→nucleic acids (RNA, DNA) →acquired self-replicating ability→ fundamental property of living form.
• Formation of Protobionts or Procells : First form of life called protobionts was formed from nucleic acids by coacervation.

Protobionts : Prebiotic chemical aggregates having some properties of living system.
Protobionts also called Coacervates (Oparin) and protenoids or microspheres (Sidney Fox)

Coacervates and microspheres were non¬living colloidal aggregations of lipids and proteinoids respectively. They turned into eobionts or protocell.

Showed growth and division and hence considered as first primitive living system.

• Formation of first cell : First cell developed by formation of RNA and DNA system. First cell was anaerobic, heterotrophic and obtained energy by chemoheterotrophic processes.

Stanley L. Miller and Harold C. Urey provided the first experimental evidence for Oparin’s chemical evolution theory.

3. RNA World Hypothesis :

• First proposed by Carl Woese, Francis Crick and Leslie Orgel in 1960.
• Sidney Altman and Thomas Cech independently found out that RNA can also act as biocatalyst which is termed as Ribozyme.
• Early life must have been based exclusively on nucleic acids, most probably RNA.

Organic Evolution-

• Evolution (Latin word, e = from; volvere = to roll) : The act of unrolling or unfolding of nature.
• Organic evolution : Slow, gradual, continuous and irreversible changes through which the present-day complex forms of the life developed (or evolved) from their simple pre¬existing forms.
• Charles Darwin’s definition of evolution :
  ‘Descent with modification’.
• Lamarck’s theory (Theory of origin of acquired characters/inheritance of acquired characters and use and disuse of organs) : The traits are acquired due to internal force, changes in environment, new needs and the use and disuse of organs. This gives rise to new species after several generations. Lamarckism was disproved by August Weismann.
• Weismann’s theory of Germplasm : Variations produced in somatic cells (somatoplasm) are not inherited while variations produced in germ cells (germplasm) are inherited to next generation.

Darwinism-

1. Darwinism or theory of origin of species by Natural Selection.
2. Darwin’s book : ‘The origin of species by Natural Selection’, wrote in 1859 after observations of variations between the tortoises and finches on Galapagos islands.
3. C. Lyell’s viewpoint on which Darwin’s theory was based : The natural forces that existed in the past are same as those existing at present.
4. Wallace also made similar observations.
5. R. Malthus provided the idea that increase in human population leads to competition and struggle for existence of human species.
6. Five main postulates of Darwinism :

• Overproduction (Prodigality of nature)
• Struggle for existence
• Organic variations
• Natural selection (H. Spencer termed natural selection as ‘survival of fittest’)
• Origin of new species

7. Evidences Darwinism include :

• Evolution of long-necked Giraffe came to existence.
• Black colour peppered moths evolved gradually as new species.
• DDT resistance

8. Drawbacks and Objections to Darwnism :

• Darwin wrongly considered minute non- heritable fluctuating variation as principal factors. They do not form part of evolution.
• He did not distinguish somatic and germinal variation and considered all variations are heritable.
• He did not explain the ‘arrival of the fittest’. He did not explain the cause, origin and inheritance of variations and of vestigial organs.
• He could not explain the extinction of species.
• Intermediate form during evolution were not recognised.
• He could not explain existence of neutral flowers and the sterility of hybrids.

Mutation Theory-

1. Hugo de Vries proposed mutation theory based on his observations on Oenothera lamarckiana.
2. Though offspring resemble their parents in many characters, some sudden and spontaneous variations are seen in them, which is said to be mutations or discontinuous variations.
3. Main features of mutation theory :

• Large, sudden and discontinuous variations, inheritable changes in a population which provide the raw material for organic evolution.
• Mutation may be useful or harmful. Useful mutations are selected by nature.
• Accumulation of useful mutations over a period of time leads to the origin and establishment of new species, while harmful mutations are eliminated by nature or can remain in population.

4. Objections to Mutation Theory :

• The large and discontinuous variations were chromosomal aberrations which bring about minor changes.
• Rate of mutation is very slow.
• Chromosomal aberrations are unstable and hence not important in evolution.

5. Speciation (Formation of new species) :

• Small Darwinian variations are directional. Variations due to mutations are large, sudden, random.
• Darwin’s opinion : Gradual, inheritable variations over a long period of time, lead to speciation.
• De Vries’s opinion : Mutations cause speciation.
• Saltation : A single step large mutation.

Modern Synthetic Theory of Evolution-

1.  R. Fischer, J. B. S. Haldane, T. Dobzhansky, J. Huxley, E. Mayr, Simpson, Stebbins, Fisher, Sewall Wright, Medel, T. H. Morgan, etc. together have synthesised the modern theory of evolution.
2. Stebbins suggested five key factors for evolution : Gene mutations, chromosomal mutations, genetic recombinations, natural selection and reproductive isolation → together bring about evolution of new species.
3. Population : All individuals of the same species form population.
4. ‘Mendelian population’ : Small groups of interbreeding populations.
5. Gene pool : Gene pool is the total genetic information or sum total of genes of all individuals in a Mendelian population.
6. Factors affecting gene pool : Migration, replacement of one generation by another in the Mendelian population.
7. Gene frequency : The proportion of an allele in the gene pool, to the total number of alleles at a given locus.
8. Factors of Modern synthesis theory:

• Gene Mutation : Sudden permanent heritable change in the genetic material is called mutation. Single gene mutations are called point mutations. Chromosomal aberrations and ploidy too cause mutations. All mutations lead to variations.
• Genetic recombination : Crossing over in sexually reproducing organisms cause variations , during gamete formation. Crossing over also create recombination.
  Crossing over : Exchange of genetic material occurs between non-sister chromatids of homologous chromosomes.
• Gene flow : Movement of genes into or out of a population. Migration of organism, or gametes (dispersal of pollens) or segments of DNA (transformation).
• Genetic drift : Any random fluctuation (alteration) in allele frequency, occurring in the natural population by pure chance. Smaller populations may show genetic drift.
• Chromosomal aberrations : The structural, morphological change in chromosome due to rearrangement cause chromosomal aberrations.

Types of aberrations :

• Deletion : Loss of genes from chromosome.
• Duplication : Repetitions of genes or doubling of chromosome number.
• Inversion : Sequence of the genes get inverted due to 180° twist.
• Translocation : Transfer (transposition) of a part of chromosome or a set of genes to a non-homologous chromosome.

Natural selection : Main driving force behind the evolution. It brings about evolutionary changes by favouring differential reproduction of genes that bring about changes in gene frequency from one generation to next generation. The ‘fittest’ (well adapted) survives and leaves more progeny. E.g. Industrial melanism in peppered moth (Biston betularia) is example of natural selection in action.

Isolation : The separation of the population of a particular species into smaller units which prevents interbreeding between them is isolation.

Isolating mechanisms : Barrier which prevents gene flow or exchange of genes between isolated populations.

Type of isolating mechanisms :

Mechanism of organic evolution-

1. During evolution population evolves and not the individual.
2. Basic processes which bring about evolution : Mutations, gene recombination, gene flow (migration),
genetic drift, natural selection, isolation and speciation.

Hardy-Weinberg’s principle-

Hardy-Weinberg’s equilibrium/principle/law states that ‘at equilibrium point both the gene (allele) frequency and genotypic frequency remain constant from generation to generation’, only in diploid, sexually reproducing, large, free interbreeding population if mating is random and in absence of selection and other evolutionary forces.
Hardy-Weinberg equilibrium equation : p² + 2pq + q² = 1

Adaptive Radiation-

Adaptive radiation is the process of evolution which results in transformation of original species to many different varieties. E.g. (1) Darwin’s Finches on Galapagos islands. (2) Australian Marsupials.

Evidences of organic evolution-

Evolutionary evidences are based on following types of disciplines : Palaeontology, comparative anatomy, embryology and molecular biology

Speciation-

• Speciation : The process of formation of a new species from the pre-existing species.
• Species : A group of similar organisms that can interbreed and produce a fertile offspring in nature.
• Types of speciation:

Geological time scale –

Human Evolution-

1. Major changes in evolutionary development of man :

• Increase in size and complexity of brain and enhanced intelligence with increased cranial capacity.
• Bipedal locomotion, erect posture.
• Opposable thumb.
• Shortening of forelimbs and lengthening of hind limbs.
• Development of chin. Orthognathous face.
• Broadening of pelvic girdle, development of lumbar curvature.
• Articulated speech, art, development of tools, social and cultural development.

2. Classification of mammals:

3. Origin and evolution of human being :

(1) Order Primates is divided into two suborders – Prosimii (including lemurs, lorises : and tarsiers) and Anthropoidea (including : New world monkeys – Ceboidea, Old world monkeys-Cercopithecoidea, Apes and :
Man – Hominoidea).
(2) Hominoidea evolved in Miocene in three • separate lines are shown as under :

• Hyalobatidae – Gibbons
• Pongidae – Gorilla, Chimpanzee and Orangutan
• Hominidae – Primates with human characteristics.

4. Palaeontological evidences of human • evolution : The available fossils are skulls, • mandibles, teeth, bones like humerus, femur and stone implements.
5. Important stages in the origin of man :

• Ape like stage : Dryopithecus
• Men-like stage : Ramapithecus
• Connecting link between ape and man : Australopithecus.
• Handy man : Homo habilis
• Ape man : Homo erectus
• Advanced prehistoric man : Homo : neanderthalensis (Neanderthal man)
• Modern man : Homo sapiens

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 10 Human Health and Diseases students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 10 Human Health and Diseases

Introduction-

1. Health : World Health Organization (WHO) define health as ‘the state of complete physical, mental and social well-being and not merely the absence of disease or infirmity’.
2. Health is metabolic and functional efficiency of living organisms.
3. Hygiene : Science of rules of health.
4. Important factors to achieve good health : Hygienic balanced diet, clean drinking water, personal and community hygiene, regular physical exercise, knowledge about diseases and their effect on body, proper disposal of wastes and control of vectors.
5. Immune system : The ability to resist almost all types of these foreign bodies is possible due
   to immune system. It protects human beings from various pathogens or infectious agents.
6. Resistance : The ability to prevent the damage or disease, through our defence mechanism.

Immunity-

1. Immunity: Immunity is the resistance exhibited by the host towards infections caused by pathogens and their products.
2. Immunology: Study of immune system, immune responses to foreign substances and their role in resisting infection by pathogens.
3. Edward Jenner : Started the concept of immunity. Cowpox vaccine was developed by him.
4. Antigen : Any foreign substance invading body and capable of stimulating an immune response.
5. Antibody : The protective chemicals produced by immune cells in response to antigens are called antibodies.

6. Types of immunity-

7. Innate immunity :

• Inborn immunity which is non-specific and not affected by immunization.
• The barriers of innate imunity are as follows:
  

8. Acquired immunity :

(1) Specific or adaptive immunity acquired during lifetime due to infections.
(2) It involves formation of antibodies from the destruction of foreign antigens.
(3) Unique features of acquired immunity are specificity, diversity, discrimination between self and non-
self and memory.
(4) Types of acquired immunity :

9. Cells of immune system :

10. Mechanism of action of B-lymphocytes to antigens :

B-lymphocytes → sensitized directly by antigens and helper T-cells.
Activated B-lymphocyte → multiplies rapidly → Clone of plasma cells and memory B-cells produced → Plasma cells produce → Glycoproteins, called antibodies → Antibodies circulated through humor/ body fluids like blood and lymph → The antibody → bind to a cell membrane or they remain free.

11. Three main functions of free antibodies :

Agglutination	Opsonisation	Neutralization
Immobilization of foreign particles in mass and then engulfing them by phagocytes.	Coating the bacteria to facilitate the phagocytosis by macrophages.	Neutralizing toxins released by bacteria.

12. Vaccination :

• Vaccination : Administration of inactivated pathogen or antigenic protection of particular pathogen for protecting against a particular pathogen, is called vaccination.
• Vaccine : Inactivated pathogen or antigens of a specific disease.
• Vaccination is a primary prevention as it helps the body to recognize and eliminate pathogenic organism.
• Disease control on mass scale is done through vaccination. E.g. Measles, polio, tetanus and whooping cough, tuberculosis, etc. are prevented through vaccination.

Structure of antibody-

1. Antibodies are highly specific glycoproteins which can neutralize specific antigens.
2. Chemically they are Immunoglobulins (Igs), produced after antigenic stimulation.
3. Production in plasma cells which are formed by B-lymphocytes.
4. Rate of production of antibodies is very rapid, i.e. about 2000 molecules/second.
5. Structure of antibody :

• ‘Y’-shaped molecule. Having four polypeptide chains : Two heavy or H-chains and two light or L-chains.
• Y-structure formed from four polypeplidc chains are held together by disulfide bonds (-s-s-).
• Hinge : This is region holding together arms and stem of antibody.
• Two distinct regions : Variable region and the constant region.
• Paratope : This is antigen binding site present in variable region.
• Epitope : Antigen has antigenic determinant site, called epitope.
• Bivalent antibodies : Antibodies having two antigen binding sites.
• Serology: Study of antigen-antibody interactions.
• FormatIon of antigen-antibody complex: Epitopes (On antigens) and paratopes (on antibody) react with each other. Each antibody Is specific for specific antigen due to variable regions having small variations. Specific antibody binds to specific antigen forming an antigen-antibody complex.
• Antigen on Blood Cells: Antigens (A, B, D) on the surface of human red blood cells : responsible for different blood groups.
•  Blood group systems : ABO, Rh. Duffy, Kidd. Lewis, R MNS, Bombay blood group. etc.

(12) ABO Blood Groups:

(13) Rh factor :

• Landsteiner and Wiener (1940) discovered Rh factor or D antigen on the surface of RBCs of Rhesus monkey. Hence called Rh factor.
• Rh positive (Rh+ve) person has D antigen. Rh negative person lacks it.
• Rh (D) antigen induces a strong immunogenic response when introduced into Rh-ve individuals.
• Haemolytic diseases of the newborn (HDN), or erythroblastosis foetalis occurs when an Rh —ve mother conceives Rh + ve foetus.

Common Human Diseases-

10. Cancer : Cancer is caused due to abnormal, uncontrolled and purposeless division of cells which may form tumour.

(1) Neoplasm : Masses of tissue which form lumps due to uncontrolled cell division.
(2) Oncologists : Oncologists are the physicians and researchers who specialize in the study, diagnosis, treatment and prevention of cancer.
(3) Tumour is mass of undifferentiated cells.

(4) Two types of tumours :

Benign / Non-malignant Tumour:

• Slow growth and Larger size
• Does not spread to other body parts.
• Usually harmless.
• But may sometimes become malignant.
  e.g. Adenoma and Fibroid.
• Brain tumour can be fatal, though it is benign.

Malignant tumour or cancer”

• Rapid growth and not much bIgger.
• Spreads to other body parts. via blood or lymph. (The process of metastasis)
• Usually harmful.
• Overcrowding and disruption of normal cells.

(5) Types of Cancer : Five main types according to tissue on which they thrive.

(6) Causes of Cancer : Also called carcinogenic factors.

(7) Treatment of Cancer :

• Chemotherapy
• Radiotherapy
• Surgery
• Immunotherapy
• Supportive therapy

11. AIDS :

(1) AIDS : Acquired immuno deficiency syndrome, fatal and incurable illness caused by a retrovirus (ss RNA) called HIV (Human immunodeficiency virus).
Body’s immune system is weakened increasing vulnerability causing many life-threatening opportunistic infections, neurological disorders and malignancies.

(2) Structure of HIV :

• Spherical, 100 to 140 nm in diameter, with centrally located two ss RNA molecules and reverse transcriptase enzymes.
• Covering of two layers of proteins.
• The outer layer is of matrix protein (pi7) with additional layer of lipid.
• Impregnated with glycoprotein GP120 and GP 41.
• Inner layer is capsid protein (p24)
• Replication of HIV in dividing T₄ lymphocytes. They remain in latent state in lymphoid cells.

(3) Blood, semen and cerebrospinal fluid (CSF) show maximum concentration of HIV in infected person. Lesser extent seen in tears, milk, urine, saliva, cervical and vaginal secretions.

(4) Transmission of virus :

• Unsafe sexual contact : Oral, vaginal and anal sex.
• Blood : Blood transfusions or sharing syringes, needles, etc.
• Transplacental (From mother to child during pregnancy via placenta) and by nursing mother through breast milk.
• Accidental needle injury, artificial insemination with infected semen and transplantation with infected organs.
• Through urine, tears, saliva, breast milk and vaginal secretions if these secretions enter passes in the body through injury.

(5) Clinical manifestations : Four broad categories.

(6) Preventive measures :

• Prevention is the only measure as there is no cure for AIDS.
• Education of highrisk group, about HIV transmission.
• Disposable needles and syringes.
• Sexual habits to be modified.
• No sharing of toothbrushes, razors, etc.
• Blood to be screened before receiving.

Routine screening must for –

• Blood donors.
• Organ donors (kidney, liver, lung, cornea).
• Donors of semen and growth hormone.
• Patients undergoing haemodialysis.
• Pregnant females in highrisk group.

(7) Laboratory diagnosis :

• ELISA (Enzyme-Linked Immunosorbent Assay) : This test is for detection of AIDS.
• Western Blot : Second and confirmatory test which detects specific antibody to viral core protein and envelope glycoprotein.

(8) Treatment of AIDS : Antiretroviral therapy (ART) : Antiretroviral drugs for reducing viral load and prolong the life of HIV patient. E.g. TDF (tenofovir), EFV (Efavirenz), Lamivudine (3TC), etc.

Adolescence-

1. Adolescence Is transitional stage of physical and mental development during puberty and the legal adulthood. National youth policy defines phase of adolescence during 13—19 years. This period Is marked with sexual and reproductive maturity mental development, adalt Identity and transition from socioeconomic and emotional dependency to relative independence.

2. Stages of Adolescence :

3. Physical changes of adolescence:

• Growth spurt.
• Sexual development
• Emotional and social changes

4. Mental Health and Adolescence:

• Confusion, irritation. moodiness, frustration, nausea, less concentration, hyper activities, anger. effects on lifestyles like obesity, addictions, accidents, leading to ill health. etc. are common problems in adolescent age.
• Psychoses or neuroses may appear.
• Psychoses include delusions, hallucinations. disturbance In the thinking process, etc.
• AmnesIa (loss of memory). Bullirnia (extreme over indulgence in food), Anxiety (fear or apprehension), Anorexia nervosa (emotional aversion to food) depression (sadness, inactivity reduced to enjoy life, etc.), illusions, hallucination, etc.
• Characterized by number of cognitive, emotional, behavioural, physical and attitudinal changes.
• Parental communication and other conditions mould the adult personality.
• Improper peer pressure may result into addictions, like smoking, taking drugs, etc.

5. Treatment: Treatment of such disorders should be done only through counselling and not medicines with due respect to rights of children. Mental health Gap Action Programme (mhGAP) gives the guidelines as per WHO for treating such cases. Parental relations are most important in any treatment.

Addiction –

1. Addiction : Compulsive use of substance despite its harmful consequences is addiction. Addiction cause the impairment of physical, physiological and psychological functions of the body.
2. Addictive substances : Alcohol, opioids, cocaine, nicotine and some behaviours such as gambling.
3. All addictive behaviours share key neurobiological features, involving brain pathways of reward and reinforcement.
4. Neurotransmitter dopamine released during motivation.
5. Neurological changes are reversible after the substance abuse or behaviour is discontinued.
6. Causes of substances abuse during adolescence :

• Parental neglect and insufficient parental supervision and monitoring.
• No communication between child and parents.
• Absence of poorly defined rules.
• Family conflicts.
• Favourable parental attitudes towards alcohol and drug uses.
• Risk taking behaviour.

7. Measures to control drug abuse :

• Always remember ‘Prevention is better than cure’.
• Children should not be pressurized. Over expectations from them should be avoided.
• Suitable education and counselling whenever required.
• Sublimation and channelization of the energy of child in sports, studies and other constructive activities.

Drugs Abuse-

1. Drugs and alcohol use in youth leads to many harmful effects. Improper lifestyle with dangerous behaviour pattern should not be accepted as it is hazardous for all.
2. The drugs of abuse are opioids, cannabinoids and alkaloids of coca and hallucinogens.

3. Addiction and Dependence :

• Inherent addictive nature of alcohol and drugs result into psychological attachment to certain effects-such as euphoria and a temporary feeling of well-being.
• Repeated use of drugs increases the tolerance level of the receptors present in our body.
• Person getting addicted, starts self-destructive behaviour.
• Withdrawal symptoms : If regular addictive substance is discontinued, it results in withdrawal symptoms. All the symptoms seen in such person is called withdrawal syndrome, which is characterized by anxiety, trembling, nausea and sweating.

4. Effects of Drug/Alcohol Abuse :

• Reckless behaviour, vandalism and violence.
• Excessive doses of drugs can cause coma and death due to respiratory failure, heart failure or cerebral haemorrhage.
• Overdose and even deaths occur if there is weird combination of drugs and alcohol.

5. Warning signs of drug and alcohol abuse among youth :

• Drop in academic performance.
• Unexplained absence from school/college.
• Lack of interest in personal hygiene, withdrawal, isolation, depression, fatigue, aggressive and rebellious behaviour, deteriorating relationships with family / friends.
• Loss of interest in hobbies.
• Change in sleeping and eating habits.
• Fluctuations in weight, appetite, etc.
• May turn to crime for money.

6. Other hazards : Intravenous injections of drugs can cause serious infections like HIV and hepatitis B.

7. Long-term effects : Loss of equilibrium, liver cirrhosis, pancreatitis. Damage to nervous system and liver (cirrhosis). Use of drugs and alcohol during pregnancy adversely affects the foetus.

8. Performance enhancers :

• Sportspersons use drugs to enhance performance.
• Narcotic analgesics, anabolic steroids, diuretics and certain hormones to increase muscle strength and bulk and to promote aggressiveness and overall improvement in their performance.
• Anabolic steroids have side effects :

(a) Effects in females : Masculinization in females, increased aggressiveness, mood swings, depression, abnormal menstrual
cycles, excessive hair growth on the face and body, enlargement of clitoris, deepening of voice.

(b) Effects in males : Acne, increased aggressiveness, mood swings, depression and reduction of size of the testicles, decreased sperm production, kidney and liver dysfunction, breast enlargement, premature baldness, enlargement of the prostate gland.

9. Prevention and Control : Habits such as smoking, taking drug or alcohol should be avoided right from young age. Identify the situations which can form addictions and take remedial measures. Help from parents and teachers should be sought.

By going through these Maharashtra State Board 12th Science Chemistry Notes Chapter 9 Coordination Compounds students can recall all the concepts quickly.

Maharashtra State Board 12th Chemistry Notes Chapter 9 Coordination Compounds

Coordination compound : It consists of a central metal atom or ion surrounded by atoms, molecules or anions called ligands bonded by coordinate bonds, e.g. cisplatin, Pt(NH3)2Cl2, [Cu(NH3)4]S04.

According to Werner’s theory, metal atom or ion in the complex has primary valence (outer sphere) and secondary valence (inner sphere).

Coordination number (C.N.) : The number of ligand donor atoms directly bonded to the central metal atom or ion by coordination bonds or number of electron pairs involved in the coordinate bonds is coordination number (C.N.).

Ligands:

• Monodentate ligands (Cl^–, OH^–, NH₃, H₂O, etc.)
• Bidentate (en, C₂O₄^2- etc.)
• Tridentate (dien)
• Tetiadentate (trien)
• Hexadentate (EDTA)

Classification of complexes on the basis of types of ligands :

• Homoleptic complexes Ni(CO)₄, [CO(NH₃)₆]Cl₃
• Heterleptic complexes [CO(NH₃)₄Cl₂H₂O]Cl

Classification of complexes on the basis of charge :

• Cationic sphere complexes, [Zn(NH₃)₄]²⁺ , [CO(NH₃)₅Cl]²⁺
• Anionic sphere complexes, [Ni(CN)₄]^2-, [Fe(CN)₆]^3-
• Neutral sphere complexes, [Pt(NH₃)₂Cl₂], [Ni(C0)₄]

Effective atomic number : EAN = Z – X + Y

Isomerism in complexes :

(1) Stereoisomerism :

• Geometrical isomerism
• Optical isomerism

(2) Structural isomerism :

• Ionisation isomerism
• Linkage isomerism
• Coordination isomerism
• Solvate isomerism

Bonding in complexes:

• Valence bond theory (VBT)
• Crystal field theory (CFT)
• Ligand field theory (LFT)
• Molecular orbital theory (MOT)

Valence bond theory (VBT) : A central.metal atom or ion undergoes hybridisation like sp3, dsp2, d2sp3, etc. forming hybridised orbitals to accommodate the lone pairs of electrons from the ligands.

Inner complex : (n — 1)d orbitals of metal are used.
Outer complex: nd orbitals of metal are used.

Crystal field theory (CFT) :
Degenerate d-orbitals: d_xy, d_yz, d_zx, d_{(x² – y²)} and d_z²

Crystal field splitting:

(1) For octahedral complex:

(2) For tetrahedral complex :

Factors affecting the stability of the complex :

1. Charge to size ratio of the metal ion
2. Nature of ligands

Applications of the coordination compounds:

• In biology
• In medicines
• To estimate the hardness of water
• In electroplating