Bhagya

By going through these Maharashtra State Board 12th Science Chemistry Notes Chapter 10 Halogen Derivatives students can recall all the concepts quickly.

Maharashtra State Board 12th Chemistry Notes Chapter 10 Halogen Derivatives

Classification of Halogen derivatives –

Halogen derivatives:

1. Haloalkanes
2. Haloalkenes
3. Haloalkynes
4. Haloarenes

Halogen derivatives:

• Monohalogen compounds
• Dihalogen compounds
• Trihalogen compounds

Alkyl halides or Haloalkanes:

1. Primary alkyl halide
2. Secondary alkyl halide
3. Tertiary alkyl halide

Alkyl halides (Based on halogen atom bonded to sp³, sp² and sp hybridised carbon):

• Allylic halide
• Benzylic halide
• Vinylic halides
• Haloalkyne
• Aryl halides

Preparation and Reactions of alkyl halides :

Preparation of haloarenes :

Reactions of chlorobenzene:

Uses and environmental effects :

1. Dichloromethane (CH₂C₁₂)
2. Chloroform (CHCl₃)
3. Carbon tetrachloride (CCl₄)
4. Iodoform (CHI₃)
5. Freons (CCl₂F₂)
6. Dichlorodiphenyltrichloroethane (DDT)

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 4 Molecular Basis of Inheritance students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 4 Molecular Basis of Inheritance

The Discovery of DNA-

1. Nuclein:

• Isolated by Friedrich Miescher, in 1869, from the nuclei of pus cells.
• It is an acidic substance with high phosphorus content.

2. There are two types of nucleic acids – DNA  (deoxyribonucleic acid) and RNA (ribonucleic : acid).

The Genetic Material is a DNA-

1. Initially proteins (and not DNA) were ; considered as genetic material because :

• Proteins are large, complex molecules and store information required to govern cell metabolism. Hence, it was assumed that variations found in species were caused by proteins.
• DNA was considered as a small, simple : molecule whose composition varies little ; among species.
• Variations in the DNA molecules are different j than the variation in shape, electrical charge J and function shown by proteins.

2. Various experiments which proved that DNA (and not protein) was the genetic material are as follows :

A. Griffith’s experiments :

• In 1928, Frederick Griffith, carried out an experiment with two strains of bacterium Streptococcus pneumoniae: S-type (Virulent, smooth, pathogenic and encapsulated) and R-type (Non-virulent, rough, non-pathogenic and non-capsulated).
• He observed that on injecting a mixture of heat-killed S bacteria and live R bacteria, the mice died.
• Griffith obtained live S-strain bacteria from the blood of the dead mice.
• Conclusion: Live R-strain bacteria must have picked up something (transforming principle) from the heat-killed S bacterium and got transformed into S-type.

B. Avery, McCarty and MacLeod’s experiment:

• Purified DNA, RNA, proteins, etc. from heat killed cells of S-strain and mixed with R-strain bacteria separately.
• Only DNA was able to transform avirulent R-strain into virulent S-strain.
• When DNA was digested with DNase, there was no transformation.
• Thus, in 1944, they proved that the DNA is a genetic material (transforming principle), but all biologists were not convinced.

C. Hershey-Chase Experiment :

• Hershey and Chase worked with bacteriophages.
• TWo types of bacteriophages were used in the experiment – type one where DNA was labelled with radioactive phosphorus and type two where protein coat was labelled with radioactive sulphur.
• Steps : infection, blending, centrifugation.
• Experiment proved that DNA is the genetic material which enters bacterial cell and not protein.

DNA packaging-

A. Packaging in Prokaryotes :

• E. coli cell size : 2-3μ.
• The nucleoid : Small, circular, highly folded, naked DNA (1100μm long in perimeter, contains about 4.6 million base pairs), nuclear membrane, nucleolus are absent.
• Negatively charged circular DNA (350 μm in diameter).
• Folding / looping : Size reduction to 30 μm in diameter.
• Coiling and supercoiling of each domain : Size reduction to 2μ in diameter.
• Positively charged HU (Histone like DNA binding proteins) proteins : Assist in coiling.
• DNA gyrase and DNA topoisomerase I : Maintain super coiled state.

B. Packaging in Eukaryotes :

• Presence of nuclear membrane, nucleolus and thread-like chromosomes.
• To accommodate long DNA molecule (2.2 m in a typical mammalian cell) in such a small nucleus (10^-6 m), it is condensed, coiled and supercoiled.
• R. Kornberg in 1974 reported that DNA is associated with histone and non-histone proteins in the chromosomes.
• Histones: A set of positively charged, basic proteins, rich in basic amino acid residues lysine and arginine.
• Nucleosome: Consists of nucleosome core (two molecules of each of histone proteins viz. H₂A, H₂B, H₃ and H₄ forming histone octamer) and negatively charged DNA (146 bps) that wraps around the histone octamer by 1 3/4 turns.
• H₁ protein binds the DNA thread where it enters and leaves the nucleosome.
• Adjacent nucleosomes are linked with linker DNA (varies in length from 8 to 114 bp, average length of linker DNA is about 54 bp). [Note : Technically nucleosome includes nucleosome core, DNA wrapped around it (146 bp) and one adjacent linker DNA (54 bp), thus, each nucleosome contains 200 bp of DNA.]
• Packaging involves formation of – Beads on string, Solenoid fibre (looks like coiled telephone wire, 30 nm diameter/300 Å), Chromatin fibre and Chromosome.
• Non-Histone Chromosomal Proteins (NHC) : Additional sets of proteins that contribute to the packaging of chromatin at a higher level.

C. Heterochromatin and Euchromatin :

1. Heterochromatin :

• This term was proposed by Heitz.
• Genetically (transcriptionally) almost inactive, darkly stained, condensed parts of chromonema/chromosomes observed in eukaryotic cells, during interphase and early prophase.
• Located near centromere, telomeres are also interrelated.
• Heterochromatin is 2 to 3 times richer in DNA than in the euchromatin.

2. Euchromatin : Genetically (transcriptionally) . active, lightly stained, fast replicating regions of chromonema which are in non-condensed state.

DNA Replication-

1. Functions of DNA :

• Regulates and controls all the cellular activities.
• DNA replicates and gets distributed equally to the daughter cells when the cell divides.
• Carrier of genetic information.
• Heterocatalytic function : Directs the synthesis of chemical molecules other than itself. E.g. Synthesis of RNA (transcription), synthesis of protein (Translation), etc.
• Autocatalytic function : Directs the synthesis of DNA itself. E.g. Replication.
• A master molecule of a cell that initiates, guides, regulates and controls the process of protein synthesis.

2. Replication is the process by which DNA duplicates itself and forms two copies that are identical to it.
3. In eukaryotes, replication of DNA occurs once, in the S-phase of interphase.
4. The steps involved in DNA replication :

• Activation of Nucleotides
• Point of Origin or Initiation point
• Unwinding of DNA molecule
• Formation of Y-shaped replicating fork
• Synthesis of new strands
• Leading and Lagging strand
• Formation of daughter DNA molecules

5. Enzymes and proteins involved in DNA replication :

• Phosphorylase
• Helicase
• Single strand binding proteins (SSBP)
• Primase
• DNA polymerase
• DNA ligase
• Super-helix relaxing enzyme
• DNA gyrase (Topoisomerase)

6. Semiconservative replication : In each daughter DNA molecule, one strand is parental and the other one is newly synthesized. Thus, 50% mother DNA is conserved.
7. Experimental confirmation of semiconservative DNA replication : Given by Matthew Meselson and Franklin Stahl (1958). They used light and heavy isotopes of nitrogen and equilibrium-density-gradient-centrifugation technique.

Protein synthesis-

1. Central Dogma :

(1) Postulated by F.H.C. Crick in 1958.

Transcription Translation
(2) In eukaryotes, DNA transcription takes place in nucleus and translation occurs in cytoplasm. In prokaryotes, both the processes occur in cytoplasm.
(3) Central dogma in retroviruses : Temin (1970) and Baltimore (1970)

2. Transcription :

(1) Transcription is the process of copying of genetic information from one (template) strand of DNA into a complementary single stranded RNA transcript.
(2) Occurs in the nucleus during Gx and G2 phases of cell cycle.

(3) Catalyzed by RNA polymerase :
(i) Prokaryotes : One type of RNA polymerase.
(ii) Eukaryotes :

• RNA polymerase-I : Transcription of r-RNA.
• RNA polymerase-II : Transcription of m-RNA and heterogeneous nuclear- RNA (or hnRNA).
• RNA polymerase-III : Transcription of t-RNA and small nuclear-RNA (snRNA).

(4) Transcription Unit: Transcription unit (Each transcribed segment of DNA) consists of the promoter, the structural gene and the terminator.

(i) The promoter :

• Located towards 5′ end of structural gene, i.e. upstream.
• Provides binding site for enzyme RNA polymerase.

(ii) Structural genes :

• Template strand : DNA strand having 3′->5′ polarity.
• Sense strand : The other strand of DNA having 5′->3′ polarity.

(iii) The terminator :

• Located at 3′ end of coding strand, i.e. downstream.
• Defines the end of the transcription process.

(5) Three stages of transcription : Initiation, Elongation and Termination.
(6) Transcription unit and the gene :

• Gene : The DNA sequence coding for m-RNA/t-RNA or r-RNA.
• Cistron : A segment of DNA coding for a polypeptide.
• Monocistronic gene : A single structural gene in transcription unit.
• Polycistronic gene : One transcription unit having a set of various structural genes.
• Interrupted genes (Split genes) :
  Structural genes with both exons and introns).
  • Exons : The coding sequences or express sequences.
  • Introns : The non-coding sequences.
  • Only exons appear in processed m-RNA in eukaryotes.
• In bacteria. m-RNA does not require any processing because it has no introns.

(7) Processing of hnRNA :

• Primary transcript or hnRNA is non¬functional and contains both exons and introns.
• Processing of hnRNA results in functional m-RNA.
• hnRNA undergoes capping, tailing and splicing.
  • Capping : Methylated guanosine tri¬phosphate is added to 5′ end of hnRNA.
  • Tailing : Polyadenylation take place at 3′ end.
  • Splicing : Removal of introns.
• DNA ligase joins exons in a definite sequence (order).
• The fully processed hnRNA is called m-RNA.

(8) Genetic Code :

• Yanofski and Sarabhai (1964) : Provided evidence that DNA carries the information for the protein synthesis as the sequence of nucleotides.
• F.H.C. Crick : According to Crick the information for protein synthesis is stored in the form of coded language (cryptogram) called genetic code. He gave evidence for the triplet nature of genetic code, by using “frame-shift mutation”.
• G. Gamow (1954) : Suggested that codon is a sequence of three consecutive nucleotides on m-RNA.
• Cracking of genetic code : M. Nirenberg, Matthaei, Ochoa and Har Gobind Khorana : Deciphered complete genetic code by using artificial m-RNA templates (homopolymers and copolymers) and cell free system of protein synthesis. Synthesized artificial poly-U RNA.

(a) M. Nirenberg and Matthaei : Synthesis of poly-U, m-RNA and polypeptide that consisted of only phenylalanine.
(b) Har Gobind Khorana : Devised a technique for synthesis of artificial m-RNA with repeated sequences of known nucleotides.
(c) Severo Ochoa : The enzyme polynucleotide phosphorylase polymerizes RNA with defined sequences in a template-independent manner (i.e. enzymatic synthesis of RNA).

(9) Replication and transcription are based on complementarity principle.
(10) During translation, complementarity principle is not applicable as, genetic information is transferred from a polymer of nucleotides to a polymer of amino acids.

(11) Characteristics of Genetic code :

• Triplet code : Codon (sequence of three consecutive nucleotides), specifies one particular amino acid.
• Polarity : Genetic code is always read in 5′ -» 3′ direction.
• Non-overlapping code : Each single nucleotide is a part of only one codon.
• Commaless : There is no gap between successive codons.
• Degeneracy of genetic code : Two or more codons can specify the same amino acid. E.g. Cysteine has two codons, while isoleucin has three codons.
  Degeneracy of the code is explained by Wobble hypothesis.
• Universal code : In all living organisms the specific codon specifies same amino acid. E.g. codon AUG always specifies amino acid methionine.
• Non-ambiguous code : Each codon specifies a particular amino acid.
• Initiation codon : AUG, Codes for amino acid methionine.
• Termination codons : UAA, UAG and UGA : They do not code for any amino acid. They stop the process of elongation of polypeptide chain.
• Codon : A triplet of nucleotides present on DNA that codes for specific amino acid. E.g. AUG is codon.
• Anticodon : Triplet of nucleotides present on the anticodon loop of t-RNA, which is complementary to codon on m-RNA.
• Wobble hypothesis : In codon-anticodon pairing the third base may not be complementary.

(12) Mutation recombination :

(i) Mutation : A sudden heritable change in the DNA sequence that results in the change of genotype.
(ii) Mutation and recombination is raw material for evolution as it generates variations.
(iii) Types of mutations :

• Chromosomal mutations : Loss (deletion) or gain (insertion/ duplication) of a segment of DNA results in alteration in the chromosome.
• Point mutations : Involve change in a single base pair of DNA. E.g. mutation that results in Sickle-cell anaemia.
• Deletion or insertion of base pairs of DNA : It causes frame-shift mutations or deletion mutation.

(13) t-RNA – the adapter molecule :

• t-RNA can read the codon and also can bind with the amino acid. So t-RNA is considered as an adapter molecule.
• Cloverleaf structure (2 dimensional) of t-RNA has 3 loops and 4 arms.
• For every amino acid, there is specific t-RNA.
• Initiator t-RNA is specific for methionine.
• There are no t-RNAs for stop codons.
• In the actual structure, the t-RNA molecule looks like inverted L (3 dimensional structure).

3. Translation – protein synthesis :

• Translation is the process in which sequence of codons on m-RNA is decoded and accordingly amino acids are added in specific sequence to form a polypeptide on ribosomes.
• It requires 20 different amino acids, m-RNA, t-RNA, ribosomes, ATP Mg⁺⁺ ions, enzymes, elongation, translocation and release factors.
• Translation involves
  • Activation of amino acids and formation of AA-t-RNA complex.
  • Formation of polypeptide chain : initiation, elongation, termination.

Regulation of gene expression-

In eukaryotes, the regulation of gene expression can be at different levels like

• Transcriptional level (formation of primary transcript).
• Processing level (regulation of splicing).
• Transport of m-RNA from nucleus to the cytoplasm.
• Translational level.

Operon concept-

1. A transcriptional control mechanism of gene regulation.
2. Francois Jacob and Jacques Monod (1961) : Explained that metabolic pathways are regulated as a unit.
3. Lac operon of E. coli :

(1) An inducible operon.
(2) The operon is switched on by a chemical inducer-lactose present in the medium.
(3) Lac operon consists of the following components :

• Regulator gene (repressor gene)
• Promoter gene
• Operator gene
• Structural genes : z (codes for galactosidase), y (codes for β-galactoside permease) and a (codes for transacetylase). These enzymes are involved in lactose metabolism.

4. Inducer is not a component of operon.

Genomics-

1. The term Genome was introduced by H. Winkler in 1920.
2. Genome : The total genetic constitution of an organism or a complete copy of genetic information (DNA) or one complete set of chromosomes (monoploid or haploid) of an organism.
3. Genomics (term coined by T.H. Roderick in 1986) : The study of genomes through analysis, sequencing and mapping of genes along with the study of their functions.
4. Two types of Genomics :

• Structural genomics : Involves mapping, sequencing and analysis of genome.
• Functional genomics : Involves the study of functions of all gene sequences and their expressions in organisms.

5. Application of genomics :

• Structural and functional genomics are used in the improvement of crop plant, human health and livestock.
• The knowledge and understanding acquired by genomics research can be applied in medicine, biotechnology and social sciences.
• It helps in the treatment of genetic disorders through gene therapy.
• To develop transgenic crops having more desirable characters.
• Genetic markers have applications in forensic analysis.
• Genomics can lead to introduce new gene in microbes to produce enzymes, therapeutic proteins and even biofuels.

Human Genome Project-

1. Initiated in 1990 under the International administration of the Human Genome Organization (HUGO).
2. Coordinated by the US Department of Energy and National Institute of Health, some universities across the United States and various international partners.
3. Started in 1990 and completed in 2003.

4. Aims of HGP :

• Mapping the entire human genome at the level • of nucleotide sequences.
• To store the information collected from the, project in databases.
• To develop tools and techniques for analysis of the data.
• Transfer of the related technologies to the * private sectors, such as industries.
• Taking care of the legal, ethical and social issues which may arise from project.
• To provide complete and accurate sequence of the 3 billion DNA base pairs that make up the human genome.
• To find out the estimated number of human ; genes. Now about 33,000 genes have been : estimated to be present in humans.
• To sequence the genomes of several other organisms such as bacteria e.g. E.coli, Caenorhabditis elegans, Saccharomyces cerevisiae, Drosophil, rice, Arabidopsis), Mus musculus etc.

5. HGP was closely associated with rapid development of Bioinformatics.
6. Significance :

• Increased knowledge about the functions of genes and proteins.
• A major impact in the fields like Medicine, Biotechnology and the Life sciences.
• Increased understanding of gene structure and function in other species, such studies will enhance understanding of human evolution.

7. Comparative genome sizes of humans and other model organisms.

DNA Fingerprinting-

1. Every individual has its unique genetic make- up, called its Fingerprint.
2. Reasons for Uniqueness of fingerprint :

• Recombination of paternal and maternal genes, because of which we differ from our parents.
• Infrequent mutations that occur during gamete J formation (cell division).

3. The DNA profiling or DNA fingerprinting j technique (developed by Dr. Alec Jeffreys in 1984) identifies a person with the help of DNA restriction analysis.

4. It is based on identification of nucleotide sequence present in DNA.

• About 99.9% of nucleotide sequence in all persons, is same.
• Variable Number of Tandem Repeats (VNTRs) : Unusual sequences of 20 – 100 base pairs, which are repeated several times.
• As the length of the regions having VNTRs is different in each individual, they are the key factor in DNA profiling.

5. Steps involved in DNA finger printing :

• Isolation of DNA
• Restriction digestion
• Gel electrophoresis
• Southern blotting
• Selection of DNA probe
• Hybridization
• Photography

6. Application of DNA fingerprinting :

•  Used in forensic sciences to solve rape and murder cases.
• Finds out the biological father or mother or both, of the child, in case of disputed parentage.
• Used in pedigree analysis in cats, dogs, horses and humans.

Know the scientist :
Dr. Lalji Singh (1947-2017) :

• Father of DNA fingerprinting in India.
• A unique segment obtained from Y chromosome of female banded krait snake (banded krait minor – B_KM-DNA) was used by him to develop probe for DNA fingerprinting.

His contributions :

• Established laboratories for research in fields like genetics, population biology, structural biology and transgenics.
• Established centre for DNA Fingerprinting and Diagnostics (CDFD) for all species and several diseases.
• Founded laboratory for Conservation of Endangered Species (LaCONES).
• Applied of DNA fingerprinting technology for wildlife conservation, forensics, evolution and phylogenetic research.

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 9 Control and Co-ordination students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 9 Control and Co-ordination

Introduction-

• Plants show control and coordination by sending chemical signals and bringing about various types of movements.
• Animals control and coordinate the body’s activities by electrical and chemical signals.
• The nervous system and endocrine control system are two coordinating systems in them.

Nervous Coordination

Nervous System in Hydra-

• Hydra → diffused nervous system in the form of nerve net.
• Two nerve nets in the mesoglea, one connected towards the epidermis and second towards the gastro-dermis.
• Sensory cells scattered in the body wall and tentacles, but no sense organs
• No sensory and motor nerves.

Nervous System in Planaria (flatworm)-

• Primitive animal with a central nervous system (CNS) located on the ventral side of body.
• Mass of cerebral or cephalic ganglion appearing like an inverted U-shaped brain.
• Ventral pair of nerves arising from ganglia. Interconnected to each other by transverse nerve or commissure in a ladder like manner.
• The peripheral nerve plexus arising laterally from VNC.

Neural tissue-

1. Two types of cells in neural tissue – the neurons and the neuroglia or glial cells.
2. Nerve is bundle of axons. Outside the CNS, it is called nerve while inside it is called tract.
3. Types of nerves : Sensory (with sensory * fibres), motor (with motor fibres) and mixed * type (with both sensory and motor fibres).
4. Neurons/Nerve cells :

• Neuron is structural and functional unit of * the nervous system.
• Each multipolar neuron has three parts – cyton : or cell body, dendron and axon.

5. Grey matter and white matter :

• Grey matter is darker part of CNS. This is due to presence of cytons.
• White matter is lighter part of CNS. This is due to presence of myelin sheaths around axons.

In PNS however, the accumulation of cyton causes a swelling on the nerve. Such a swelling is called ganglion, [cytons within CNS form nuclei while those in PNS form ganglia]

6. Connective tissue layers in a nerve are :

• Endoneurium : covers each nerve fibre
• Perineurium : covers each nerve bundle having a number of neurons
• Epineurium : covers many nerve bundles to form a peripheral nerve

7. Neuroglial cells :

• More in number than the neurons.
• They are supporting cells of the Central Nervous System (CNS) and Peripheral Nervous System (PNS).
• Neurilemma is the plasma membrane of Schwann cell.

8. Tjrpes of neuroglial cells :

Synapse-

1. Junction between two nerve cells with a minute gap (synaptic cleft) in between them which allows transmission of impulse by a neurotransmitter bridge.
2. When the telodendria are connected to muscle fibre, it is called motor end plate or neuro¬muscular junction.
3. Properties of nerve fibres :

•  Excitability/Irritability
• Conductivity
• Stimulus
• Summation effect
• All or none law
• Refractory period
• Synaptic delay
• Synaptic fatigue
• Velocity

4. Types of synapses : Electrical synapse and Chemical synapse.

(1) Electrical synapses are found in those places of the body requiring fastest response as in the defence reflexes.
(2) A chemical synapse between a motor neuron and a muscle cell is called a neuromuscular junction or motor end plate.
There are three components of a typical chemical synapse.

• The pre-synaptic terminal
• The synaptic cleft
• The post-synaptic neuron

5. Transmission of nerve impulse across a synapse :

• This transmission takes place with the help of neurotransmitters.
• Once the neurotransmitters bind to the receptors of the post-synaptic cell, the action is either excitatory or inhibitory depending on the type of neurotransmitter.
• The enzyme like acetyl cholinesterase destroys the neurotransmitter after the transmission and the synapse is ready to receive a new impulse.

Transmission of nerve impulse along the axon-

• The excitable neurons transmit the impulse through changes in electrical charges across the neuronal membrane.
• The external tissue fluid has both Na+ and K+ ions.
• This process is called sodium pump or Na-K exchange pump.
• Generation of nerve impulse : Occurs through depolarization.
• Saltatory conduction takes place in medullated nerve fibres.

Human Nervous System-

1. Central nervous system (CNS) :

• Brain is enclosed within the brain box/ cranium of the skull, whereas the spinal cord lies in the vertebral canal of the vertebral column.
• Inner to these bony structures, there are 3 protective membranes called meninges.

2. Meninges :

3. CSF (cerebrospinal fluid) :

• About 100-120 cc lymph like extra cellular . fluid with specific gravity of 1.005, present in and around the CNS.
• It is secreted by the pia mater, the choroid plexuses and the ependymal cells lining the ventricles of the brain and central canal of spinal cord.

4. Functions of meninges and CSF :

• Shock absorber, protection, prevention of desiccation.
• Maintaining constant pressure inside as well as outside the CNS.
• Exchange of nutrients and wastes between blood and brain tissue.
• Supply of oxygen to the brain.

5. The Human brain :

• Encephalology : Study of all aspects of the brain.
• About 1300-1400 g in weight -and 1300-1500 cc in volume

6. Functional areas of cerebrum :

Areas	Functions
1. Frontal lobe	Motor area → controls voluntary motor activities or movements of muscles. Premotor area → higher centre for involuntary movements and autonomus nervous system.Association area → coordination between sensation and movements. Broca’s area → motor speech area.
2. Parietal lobes	Somaesthetic sensation of pain, pressure, temperature, taste
3. Temporal lobes	Centres for smell (olfactory), hearing (auditory), speech and emotions.
4. Occipital lobes	Visual area mainly for sense of vision.
5. Wernicke’s area	Present partly in temporal, parietal and occipital lobes. Sensory speech area.
6. Basal nuclei or basal ganglia	Control precise muscular activities at subconscious level.
7. Corpus striatum	At the floor of cerebrum is the largest basal nucleus.

7. Parts of the Hindbrain (Rhombencephalon) :

8. Parts of the Midbrain (Mesencephalon):

9. Parts of the Hindbrain (Rhombencephalon) :

10. Ventricles of brain : The cavities present in the different parts of the brain are called ventricles.

11. Important terms associated with brain.

• Corpus callosum : Transverse band of nerve fibres which connects right and left cerebral hemisphere. It is the largest commissure of the brain.
• Cerebral cortex : The outer surface of cerebrum, composed of grey matter.
• Cerebral medulla : Inner part composed of white matter.
• Gyri (elevations) and Sulci (depressions) : convolutions and grooves on the surface of cerebrum.
• Central sulcus : Between frontal lobe and the parietal lobes.
• Parieto-occipital sulcus : Between parietal and occipital lobes.
• Lateral or Sylvian sulcus : Between temporal lobe and frontal and parietal lobes.
• Insula or insular cortex : Fifth lobe which is folded deep within the lateral sulcus.
• Foramen of Monroe : Narrow opening through which two lateral ventricles communicate with diocoel (third ventricle).
• Pineal gland : Vestigial 3rd eye and an important endocrine gland, producing hormones melatonin and serotonin.
• Habenular commissure : Connects two thalami.
• RAS (Reticular Activating System) : Relay centre as it transmits all sensory impulses except those of olfactory to the cerebrum. Situated in thalami.
• Aqueduct of Sylvius or iter : Connection between third and fourth ventricle through hypothalamus and midbrain.
• Limbic system : A complex neuronal circuit formed by the hypothalamus, amygdala, parts of epithalamus and thalamus, hippocampus and other areas.
• Optic chiasma : Crossing of the two optic nerves.
• Corpora quadrigemina : Four rounded elevations on the dorsal surface of the midbrain. The two superior colliculi are involved in visual reflexes and the two inferior colliculi are for auditory reflexes.
• Crura cerebri : Two thick fibrous tracks, also called cerebral peduncles, situated in the floor midbrain.
• Red nucleus : Grey matter near the centre of the midbrain, controlling posture. and muscle tone, modifying some motor activities and motor coordination.
• Pons varolii : Rounded bulge on the underside of the brain stem.
• Brain stem : Consist of midbrain, pons and medulla.
• Arbor vitae : The mixing of white matter with the grey matter showing a branched tree-like pattern.
• Cerebellar peduncles : Three pairs of myelinated nerve bundles connecting cerebellum to the other parts of CNS.
• A pair of lateral – foramina of Luschka and a median – foramen of Magendie :
  apertures on the posterior choroid plexus.

12. Spinal Cord :

• Spinal cord is the lower extension of the medulla oblongata of the brain.
• It lies within the neural canal of the vertebral column and is surrounded by three meninges.
• Externally, the spinal cord appears as long cylindrical rod.
• It is 42 to 45 cm long and 2.0 to 2.5 cm broad.
• Conus medullaris : Terminal nervous part of the spinal cord.
• Filum terminate : Thread like non-nervous extension.
• 31 pairs of spinal nerves arise from lateral sides of the spinal cord.
• Cauda equina – Filum terminale with some spinal nerves running parallel to it. (appearing like a horse-tail)

13. T. S. of spinal cord :

• The spinal cord has a deep, narrow dorsal fissure and a broad ventral fissure.
• The inner grey matter is H-shaped and the outer white matter surrounds it.
• Grey matter is divisible into six horns, namely dorsal, lateral and ventral horns.
• The white matter is divisible into 6 columns or funiculi, namely dorsal, lateral and ventral funiculi.
• The dorsal and ventral horns extend out of the spinal cord as dorsal root and ventral root.
• The dorsal root has dorsal root ganglion which is a collection of unipolar sensory neurons. No such ganglia on ventral root.
• The adjustor/association or inter-neurons lie inside the grey matter.
• The white matter consists mainly of bundles of myelinated nerve fibre called ascending and descending tracts.

Functions :

• The spinal cord is the main centre for the most reflex actions.
• It provides pathway for conduction of sensory and motor impulses.

14. Peripheral Nervous System (PNS) : The peripheral nervous system connects the central nervous system to the different parts of the body having receptors and effectors.

Two types of peripheral nerves :

1. Cranial nerves : arise from the brain.
2. Spinal nerves : arise from the spinal cord.

15. Cranial Nerves :

16. Spinal Nerves:

• Thirty-one pairs of spinal nerves originate from the spinal cord.
• Spinal Nerves : All spinal nerves are mixed nerves.

17. Formation of a typical spinal nerve :

• Each spinal nerve is formed inside the neural canal of vertebral column.
• The dorsal sensory and the ventral motor nerves together form the mixed spinal nerve.
• As soon as it emerges out of vertebral column, it shows three branches, viz.
  a. Ramus dorsalis
  b. Ramus ventralis
  c. Ramus communicans

18. Reflex Action :

(1) It is a quick, automatic, involuntary and spontaneous response to stimulus,
(2) The path along which the action is carried out is called reflex arc.
(3) Components of a reflex arc :

a. Receptor/sense organ
b. Sensory/afferent neuron
c. Association/adjustor neuron
d. Motor/efferent neuron
e. Effector organ

(4) Types of reflexes :

a. Somatic and visceral
b. Cranial and spinal
c. Simple [monosynaptic] and complex [polysynaptic]
d. Unconditional and conditional
table

(5) According to recent studies, the ANS is under the control of CNS and nerves arising from it (PNS).
According to this view, the PNS is divided into
(i) Somatic nervous system
(ii) Autonomic nervous system

19. Autonomic Nervous System (ANS) :

• Autonomic nervous system transmits impulses from CNS to the involuntary organs and smooth muscles of the body.
• It includes – autonomic ganglia,
  preganglionic fibres and postganglionic fibres.
• Autonomic ganglia include
  • Sympathetic ganglia – present near CNS in the form of sympathetic cord.
  • Parasympathetic ganglia – present near or on the effector organs.
• Preganglionic fibres arise from grey matter of CNS and end at autonomic ganglia.
• Postganglionic fibres arise from autonomic ganglia to the effector organs.
  Autonomic nervous system consists of sympathetic and parasympathetic nervous system.

(1) Sympathetic Nervous System (SNS) :

• Also called thoraco-lumbar outflow.
• Consists of 22 pairs of sympathetic ganglia which lie near vertebral column.
• Post ganglion is neuron which produce adrenaline. Hence they are called adrenergic fibres.
• It works in emergencies. It is also called 3 Fs system [fright, fight and flight]. It has excitatory and stimulating effect on most organs of the body.

(2) Parasympathetic Nervous System:

• It is also called cranio-sacral outflow.
• It consists of ganglia which are very close or within the wall of the effector organs.
• Acetyicholine is produced at the terminal end of postganglionlc nerve at the effector organ. Hence these are also called cholinergic fibres.
• All activities which are stimulated by the sympathetic system are brought back to normal by this system. Hence it is also called housekeeping system.

Comparison between Sympathetic and Parasympathetic Nervous System :

Sensory Receptors-

1. Specialised structures in the body modified to receive the various stimuli from the external or internal environment.

2. Classification of receptors : Receptors are classified on the basis of their location, function and their sensitivity to specific stimuli. Their classification is given in the following chart.

Types of exteroceptors and interoceptors, their locations and functions :

3. Eye :

• The eyes are a pair of sensory organs of vision located in the orbit of skull.
• Each eye is spherical/rounded and called eyeball.
• Wall of the eyeball is made up of 3 layers : (1) sclera, (2) choroid (3) retina.

Generation of image/Mechanism of vision :

4. Ear :

• The human ear is called statoacoustic organ as it has two functions – hearing and body equilibrium.
• Anatomically the ear is made up of three divisions : the external ear, middle ear and inner ear.

(3) The organ of hearing :

• Organ of Corti is a pea sized structure located on basilar membrane. It has a sensory epithelium over the basilar membrane.
• The sensory cells have sensory hair on their free end so also called hair cell. In between the rows of hair cells are present supporting cells.
• Hair cells have long stiff microvilli called stereocillia on their apical surfaces. Above these stereocilia, is a jelly like membrane called tectorial membrane.
• This organ acts as a transducer, converting sound vibrations into nerve impulses.

(4) Other parts of the ear :

• Besides the cochlea, the internal ear also has the vestibular apparatus.
• It is composed of three semi-circular canals and the utriculo saccular region.
• All three semi-circular canals lie in different planes at right angles to each other.
• These canals are filled with endolymph. The base of each of the canal has an ampulla in which there is a sensory ridge called crista. The structure is crista ampullaris.
• The vestibule has two sensory spots – macula of saccule and utricle. The utricle is larger than saccule.

(5) Mechanism of Hearing :

Disorders of nervous system-

1. Psychological disorders :

Commonly called mental disorders. There is a wide range of conditions that affect the mood, thinking or behaviour.
Some of the major categories of psychological disorders are :

• Intellectual disability (earlier known as mental retardation),
• Autism spectrum disorder
• Bipolar disorder
• Depression
• Anxiety disorder
• ADHD (Attention Deficit Hyperactivity Disorder)
• Stress related disorders.

2. Parkinson’s disease :

• Degeneration of dopamine-producing neurons in the CNS causes Parkinson’s disease.
• Symptoms develop gradually over the years.
• Symptoms are tremors, stiffness, difficulty in walking, balance and coordination.

3. Alzheimer’s disease :

• It is the most common form of dementia.
• Its incidence increases with the age.
• Symptoms include the loss of cognitive functioning- thinking, remembering, reasoning and behavioural abilities. It interferes with the person’s daily life and activities.

Chemical Coordination

Endocrine system –

1. The cells in organisms communicate with each other through chemical signals. These cells are broadly of four types as follows :

• Autocrines : Cells release secretion to stimulate themselves.
• Paracrines : Cells release secretion to stimulate neighbouring cells.
• Endocrines : Cells release secretion to stimulate distant cells.
• Pheromones : Cells/Organs release secretions to stimulate other organism.

2. Chemical coordination is carried out by secretions of ductless glands or endocrine glands. Hence this chemical coordination system is also called the endocrine system.

3. Endocrine system :

• The endocrine system controls body activities by means of chemical messengers called hormones.
• Hormones are released directly into the blood.

4. Properties of Hormones :

• They act as chemical messengers and are effective in very low concentration.
• Hormones can function as regulators that inhibit or stimulate or modify specific processes.
• Hypersecretion or Hyposecretion of hormones leads to various disorders.
• These are metabolised after their function and are excreted through urine.

5. Mechanism of hormone action :

• Hormones are released in a very small quantity.
• They produce their effect on the target organs/cells by binding to hormone receptors.
• The hormone receptors may be on the cell membrane or may be intracellular.
• A hormone receptor complex is formed and . this leads to biochemical change in the target tissue.

(a) Mode of hormone action through membrane receptors :

• Hormones like catecholamines, peptide and polypeptide hormones are not lipid soluble. Therefore they cannot enter their target cells through plasma membrane.
• Molecules of amino acid derivatives, peptide hormones bind to specific receptor molecules located on the plasma membrane.
• The hormone receptor complex causes the release of an enzyme adenylate cyclase from the receptor site. This enzyme forms cyclic AMP from ATP of the cell.
• The hormone acts as the first messenger and cAMP is the second messenger.

(b) Mode of hormone action through intracellular receptors :

• Steroid and thyroid hormones are lipid soluble and easily pass through plasma membrane of target cell into the cytoplasm.
• In the cytoplasm, they bind to specific intra¬cellular receptor proteins forming a hormone-receptor complex that enters the nucleus.
• In the nucleus, the hormone receptor complex binds to a specific regulatory site of DNA.

Major endocrine glands-

1. Hypothalamus :

• Ectodermal in origin.
• Forms the floor of diencephalon.
• Major function is to maintain homeostasis.
• Controls the secretory activity of pituitary gland by the release and inhibiting hormones.
• All hormones of hypothalamus are peptide hormones.

2. Hormones of hypothalamus :

• Somatotropin/GHRF
• Somatostatin/GHRIF
• Adrenocorticotropin Releasing Hormone
• Thyrotropin Releasing Factor .
• Gonadotropin Releasing Hormone (GnRH)
• Prolactin Inhibiting Hormone (Prolactostatin)
• Gastrin Releasing Peptide (GRP)
• Gastric Inhibitory Polypeptide (GIP)

3. Pituitary gland or hypophysis :

(1) External morphology :

• Pea sized reddish-grey coloured gland.
• Controls almost all other endocrine glands, hence previously it was called the master endocrine gland.
• However, hypothalamus controls it through the releasing and inhibiting factors.
• Located just below the hypothalamus and is attached to it by a stalk called infundibulum or hypophyseal stalk.
• Remains lodged in a bony depression called sella turcica of the sphenoid bone.
• Consists of two lobes called anterior lobe (Adenohypophysis) and posterior lobe (Neurohypophysis). Intermediate lobe (Pars intermedia) is a small reduced part lying in the cleft between the anterior and posterior lobe.
• Neurohypophysis is connected directly to the hypothalamus by axon fibres forming hypothalamo- hypophyseal tract,
• Adenohypophysis and intermediate lobe are connected to the hypothalamus through hypothalamo- hypophyseal portal system.

(2) Parts, morphology, histology and functions of pituitary in a glance :

(3) Hypothalamo – Hypophyseal portal system :

• Various hormones secreted by hypothalamus reach the pituitary gland through this portal system.
• The portal vein collects blood from various parts of hypothalamus and opens into anterior lobe of pituitary.
• From pituitary, the vein finally carries the blood into the superior vena cava.

(4) Hormones of pituitary and their role :

4. Pineal gland :

• The pineal body/pineal gland is given off from the roof of diencephalon. It is located between the two cerebral hemispheres.
• The pineal gland is sensitive to the biochemical signals of light.
• It secretes a hormone called melatonin also known as sleep hormone.

5. Thyroid gland :

(1) Morphology :

• It is the largest endocrine gland.
• The two lobes of thyroid gland are connected a non-secretory band called isthmus.

(2) Internal structure :

• The thyroid lobes are composed of rounded follicles held together by interfollicular connective tissue called stroma.
• The stroma contains blood capillaries and small group of parafollicular cell or ‘C’ cells.
• Thyroid follicles Eire composed of cuboidal epithelium resting on a basement membrane and is filled with a gelatinous colloid.

(3) Thyroid hormones :

• The two hormones secreted by the follicular cells are Thyroxine/tetra iodothyronine/T₄ (four atoms of iodine) and Triiodothyronine or T₃ (three atoms of iodine).
• Parafollicular cells produce a hormone thyrocalcitonin whose production is not under the control of TSH.

(4) Formation of T₃ and T₄ :

• Thyroxine is synthesized by attaching iodine to amino acid tyrosine by enzymatic action.
• The amino acid tyrosine molecule binds to iodine to produce Monoiodotyronine (T₁) or 2 atoms of iodine to produce Diiodothyroninc (T₂).
• T₁ and T₂ molecules bind end to end to make colloidal mass inside the follicle. They are further metabolised to prepare T₃ and T₄.

(5) Functions of Thyroid hormones :

• Regulation of the basal metabolic rate of body.
• Regulation of metabolism by stimulating protein synthesis and promotes growth of body tissues.
• Calorigenic effect as it helps in thermoregulation by increasing heat production.
• Increases action of neuro transmitters – adrenaline and nor adrenaline.
• Supports the process of RBC production and maintenance of water and electrolyte balance.
• Regulates reproductive cycles in females.
• Parafollicular cells or ‘C’ cells produce thyrocalcitonin hormone, which regulates calcium metabolism.
• Calcitonin is the active form of hormone, which is hypocalcemic hormone. It regulates the concentration of calcium and phosphorus in the blood.

(6) Disorders related to thyroid gland :

6. Parathyroid gland :

• Situated on the posterior surface of the lobes of thyroid gland.
• 2 pairs, named as superior and inferior parathyroid glands.
• Cells are arranged in a compact mass.

(4) Hormones :

• The parathyroid secretes a peptide hormone called parathormone (PTH). It is also called
  Collip’s hormone.
• Regulates calcium and phosphate balance between blood and other tissues. It is a hyper calcemic hormone. Release of parathormone increases blood calcium level.
• It stimulates osteoclast of bones to stimulate bone resorption.
• Thus, parathormone and calcitonin are antagonistic hormones.

(5) Disorders :

Hyposecretion of parathormone	Hypersecretion of parathormone
Parathyroid tetany or hypocalcaemic tetany.	Osteoporosis.
Lowers concentration of calcium in the blood. This increases excitability of nerves and muscles causing muscle twitch and spasm.	Responsible for more resorption of calcium from bones i.e., demineralization of bones resulting in softening, bending and fracture of bone.

7. Thymus gland :

(1) Located in the upper part of thorax on the dorsal side of the heart just behind sternum.
(2) Prominent gland at birth till puberty but gets gradually atrophied in the adult due to action of sex hormones.

(3) Functions:

• Secretes the hormone thymosin.
• Important role in the development of immune system by maturation of T-lymphocytes.

8. Adrenal gland/Suprarenal gland:

(1) Adrenal glands have dual origin from mesoderm and ectoderm.”
(2) Located on the upper border of each kidney.
(3) Small. conical yellowish glands having two distinct regions, outer cortex and inner medulla.

(A) Adrenal cortex (outer)	(B) Adrenal medulla (inner)
Derived from embryonic mesoderm. Secretes many hormones together called corticoids. Main two hormones : (1) Glucocorticoids (2) Mineralocorticoids	Derived from embryonic ectoderm. Secretes main two hormones (1)   Adrenaline (epinephrine) (Emergency hormone, also called 3F hormone – (fight, flight and fright). (2)   Noradrenaline (norepinephrine). (Regulates the blood pressure under normal condition, acts as vasoconstrictor)

(4) Three concentric regions of adrenal cortex :

(5) Disorders related to Adrenal cortex :

9. Pancreas :

• Develops from endoderm.
• It is heterocrine i,e. both exocrine and endocrine gland.
• Endocrine cells of pancreas form groups of cells called Islets of Langerhans.
• There are four kinds of cells in islets of

Langerhans which secrete hormones.

• Alpha (α) cells (20%) secrete glucagon.
• Beta (β) cells (70%) secrete insulin.
• Delta ((δ) cell (5%) secrete somatostatin
• PP cells or F cells (5%) secrete pancreatic polypeptide (PP).

Disorder related to pancreas : Diabetes mellitus

• Hyperglycemia i.e. It leads to increased blood glucose level.
• Cause : Under activity of Beta cells, which results in reduced secretion of insulin.
• Types of diabetes :

(1) TYPE-1 diabetes i.e. insulin dependent diabetes mellitus (IDDM)
(2) TYPE-2 diabetes i.e. Non insulin dependent diabetes mellitus (NIDDMj.

• Diabetes causes glucosuria, excessive urination and dehydration of body tissues, degradation of fats and increase in formation of ketone bodies (ketosis).
• Administration of insulin lowers blood glucose level.

10. Gonads : Gonads are sex organs (the testes and the ovaries).

(1) Ovaries :

(2) Testes : Testes secrete male sex hormones called androgens such as testosterone.

Testosterone :

• It is secreted from interstitial cells or Leydig cells by the influence of luteinising hormone (LH).
• Rise in testosterone level in blood above normal inhibits LH secretion.
• It is also responsible for appearance of secondary sexual characters such as facial and pubic hair, deepening of voice, broadening of shoulders, male aggressiveness, etc.

11. Placenta :

• Temporary endocrine source in pregnant women which forms intimate connection between foetus and uterine wall of the mother for physiological exchange of the materials.
• During pregnancy, placenta secretes hormones such as estrogen, progesterone, HCG (Human Chorionic Gonadotropin) and human placental progesterone.

12. Diffused endocrine glands :

(1) Gastro-intestinal tract : Certain cells of gastrointestinal mucosa are endocrine in function. Their hormones play vital role in digestive processes and flow of digestive juices.

Hormone of GI tract	Function
1. Gastrin	Stimulates gastric glands to produce gastric juice.
2. Secretin	Responsible for secretion of pancreatic juice and bile from pancreas and liver.
3. Cholecystokinin CCK/ Pancreozymin PZ :	Stimulates gall bladder to release bile and stimulates the pancreas to release its enzymes.
4. Entero-gastrone/Gastric inhibitory peptide (GIP)	Slows gastric contractions and inhibits the secretion of gastric juice.

(2) Kidney :

• Hormones of kidney – renin, erythropoietin and calcitriol (calcitriol is the active form of vitamin cholecalciferol -D3).
• Renin along with angiotensin helps in maintaining the blood pressure in the renal artery by vasoconstriction.
• Erythropoietin stimulates erythropoiesis.
• Calcitriol helps in absorbing calcium from the stomach.

(3) Heart :

• Hormone of heart-Atrial natriuretic Factor /ANE
• Increases sodium excretion [natriuresis] along with water by kidneys.
• Reduces blood pressure by lowering blood volume.

13. Hormone therapy/HT :

• Use of hormones in medical treatment.
• Required for the patients during pregnancy, menopause, osteoporosis, growth hormone deficiency, insulin resistance, cancer, etc.

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.