Chapter 9: Strategies for enhancement in food production

Animal husbandry and plant breeding are two major aspects of increasing production of food.Besides these, new techniques such as embryo transfer technology and tissue culture are also of great importance to increase food production.

Animal Breeding

Animal breeding aims at increasing the yield of animals and improving the desirable qualities of the produce. Two methods of animal breeding are: inbreeding and outbreeding, based mainly on breeding work with cattle.
1. Inbreeding: It refers to the mating of more closely related individuals within the same breed for 4-6 generations. Inbreeding increases homozygosity, so it is necessary for evolving a pure line in any animal. Continued inbreeding causes inbreeding depression.
2. Outbreeding: It is the breeding of unrelated animals which may be of following three types:

  1. Outcrossing: Mating between unrelated members of the same breed which have no common ancestors on either sides of their pedigree up to 4-6 generations.
  2. Cross breeding: Breeding superior males of one breed with superior females of another breed. It allows the desirable qualities of two different breed to be combined Ex: Hisardale is a new breed of sheep in Punjab by crossing Bikaneri ewes and Marino rams.
  3. Interspecific hybridisation: Mating between memebers of two different species produces interspecific hybrids.

Controlled Breeding Experiment

Controlled breeding experiments are carried out using artificial insemination and MOET. Artificial insemination involves inseminating native cows with the semen of superior bulls of exotic or indigenous breeds. Artificial insemination helps to overcome several problems of natural mating such as comparatively lesser amount of semen is required, cows at distant places can also be fertilized, etc.

MOET(Multiple Ovulation Embryo Transfer Technology)

It is an another method used in artificial breeding. In it a cow is administered hormones, with FSH like activity, to induce follicular maturation and super ovulation i.e., instead of one egg(produce normally) 6-8 eggs are produced.
The super ovulated animal is either mated with an elite bull or artificially inseminated. The fertilized eggs at 8-32 cell stage, are recovered non-surgically and transferred to surrogate mothers. The genetic mother is available for another round of super ovulation.


Dairy Farm Management

  • Refers to management of animals for obtaining milk and other products for human consumption. It deals with processes and systems that increases yield and improve quality of milk. Dairy animals include cow, buffalo, goat, etc.
  • The best known breeds of Indian buffaloes are the Murrah(Punjab, Haryana, U.P), Jaffar Abadi(Gujarat),etc.
  • Important breeds of sheep are Deccani and Nellore breeds(for mutton), Rampur-Bushari(long coarse wool), Lohi(good quality wool, also milk), Bhakarwal(undercoat for shwals), and Nali(superior carpet wool).
  • Common breeds of goats are Malabari(Kerala), Berari(Maharashtra), Marwari(Rajasthan), Beetal(Punjab).
  • Exotic breeds of goats are Alpine(Alps), Toggenberg and Saanen.

Poultry Farm Management

  • Poultry is rearing of domesticated fowls and pigeons, etc
  • Poultry birds exclusively grown for meat are called broilers, layers are for egg production, cockerels are young male fowls and roosters are mature male fowls.
  • Some commonly used of fowls are as follows:

    • Indigenous breeds: Chittagong, Aseel, Bursa, Danki, etc
    • American breed: Plymouth, Rock, Wyandotte, Rhode Island red, new Hampshire.
    • Asiatic breeds: Brahma, Langshan, Cochin.
    • English Breeds: Sussex, Orpington, etc.
    • Mediterranean Breeds: Leghorn, Minorca, Ancona, Spanish, etc.


Care and management of honey bees is called as Apiculture. Important species of honey bees are Apis dorsata(rock bee), Apis indica(Indian bee), Apis florea(Little bee), and Apis mellifera(European bee). All of them occur in nature as wild insects.
However, because of their high economic importance, the honey bees, especially A.mellifera is domesticated and cultured.


Sericulture is the breeding and management of silk worms for the production of silk at commercial level. Perbine caused by parasitic protozoan Nosema bombyscis, Grasserie(virus), Muscaradine(fungus), Flacharie(virus) are some disease of silk worm.


Fishery is an industry devoted to the catching , processing or selling of fish, shellfish or other aquatic animals for food. Aquaculture is rearing and management of useful aquatic plants and animals like fish, oysters, mussels, prawns, etc. Pisciculture is rearing, catching and management of fish. There are two main types of fisheries:

  • Inland or fresh water fisheries: pertain to two types of waters- fresh water and brackish water. Important fresh water edible fishes of India are: Labeo rhoita(rohu), Labeo calbasu(calbusa), Catla, etc.
  • Marine fisheries: deal with the fishery aspects of the sea water or ocean. Some of the important marine fishes are- Hisla(Hisla), Aluitheronema(salmon), etc.

Blue revolution: Is concerned with fish production in India.

Plant Breeding

Plant breeding is the genetic improvement of the crop in order to create desired varieties of plant types that are better suited for cultivation, give better yields and are disease resistant. Various steps required for developing new varieties are:

  • Collection of germplasm: The entire collection having all diverse alleles for all genes in a given crop is called germplasm collection. A good germplasm collection is essential for a successful breeding programme.
  • Evaluation and selection of parents: The germplasm is evaluated so as to identify plants with desirable combination of characters. The selected plants are multiplied and used in the process of hybridisation.
  • Cross hybridisation among the selected parents: Cross hybridisation of two parents to produce hybrids that genetically combine the desired characters in one plant.
  • Selection and testing of superior recombinants: This step yields progeny plants that are superior to both of the parents.
  • Testing, release and commercialisation of new cultivars: The material is evaluated in comparison to the best available local crop cultivar- a check or reference cultivar.

Examples of some improved varieties:

  • Wheat: Kalyan sona, Sonalika, Sharbati sonora, etc.
  • Rice: Jaya and Ratna.
  • Sugarcane: Saccharum barberi, Saccharum officinarum

Plant breeding for disease resistance:

A wide range of fungal, bacterial and viral pathogens, affect the yield of cultivated crop species, especially in tropical climates. In this situation, breeding and development of cultivars resistant to disease, enhance food production.
Some microbe resistant crop varieties developed by breeding:

Plant breeding for resistance to insect-pests:

Insects and pests infections are two major causes for large destruction of crop plants. Insect resistance in host crop plants may be due to morphological, biochemical or physiological characters. Plants with resistance are developed by plant breeding methods.
Some insect pest resistant crop varieties developed by breeding are:

Plant breeding for improved food quality:

Breeding of crops with high levels of vitamins and minerals or higher protein and healthier fats are called biofortification and is the most practical aspect to improve the health of the plant. Plant breeding is undertaken for improved nutritional quality of the plants with the objectives of improvement in: protein content and quality, oil content and quality, vitamins and micronutrients and mineral content. Maize hybrids that had twice the amount of the amino acids-lysine and tryptophan and wheat variety with high protein content Atlas 66 were developed. IARI(Indian Agricultural Research Institute), New Delhi, has also developed many vegetable crops that are rich in minerals and vitamins.

Single cell protein(SCP)

  • One of the alternate source of proteins for animal and human nutrition is single cell protein. The cells from micro-organisms such as bacteria, yeasts, filamentous algae, etc. are treated in various ways, used as food and referred to as single cell protein.
  • Microbes like Spirulina can be grown on waste water from potato processing plants(containing starch), straw, animal manure, and even sewage to produce food rich in proteins, minerals, fat, carbohydrates and vitamins.

Some common used microbes as SCP producers:

  • Cyanobacteria: Spirulina
  • Bacteria: Methylophillus methylotrphus
  • Yeasts: Canadida utilis
  • Filamentous fungi: Fusarium graminearum

Plant Tissue Culture

  • Plant tissue culture is the technique of maintaining and growing plant cells, tissue or organs in vitro aseptically on artificial medium in suitable containers under controlled environmental conditions. The part which is cultured is called explant.
  • Embryoids are nonzygotic or somatic embryo-like structure which are produced by in vitro culture and have the ability to form full fledged plants.
  • Cellular totipotency is the ability of a somatic cell/explant to produce the complete organism. The explants are treated with specific anti-microbial chemicals to make free from microbes. Culture media containing inorganic salts, certain vitamins, sucrose and the desired growth regulators is provided, that is required for the desired growth and development of the explants.
  • Hormones used in plant tissue culture are auxin, cytokinins, gibberellins, ABA, polyamines. Three conditions for in vitro culture
  • Producing thousands of plants through tissue culture is called micropropagation. Each of these plants will be genetically identical to the original plant from which they were grown, i.e. they are soma clones. Many important food plants like tomato, banana, apple, etc. have been produced on commercial scale using this method.
  • Steps in micropropagation include initiation of culture from an explant on a suitable nutrient medium, shoot formation from the explant, rooting of in vitro developed shoots, hardening of plantlets and transplantation to fields.
  • Depending upon the type of explant, tissue culture is called shoot tip culture, multiple shoot culture, anther/haploid culture, embryo culture, embryoid culture, etc.

Protoplast culture and Somatic hybridization

  • When a hybrid is produced by fusion of somatic cells of two varieties or species, it is known as somatic hybrid and the process is called somatic hybridization.
  • First, the cell wall of the plant cells are removed then the protoplasts of the two plants are brought in contact and made to fuse by means of electrofusion or chemicals like polyethylene glycol(PEG) and sodium nitrate. The fused protoplasts soon develop their own walls and then they are called somatic hybrid cells.
  • Successful somatic hybrids have also been obtained from different species of Brassica, Petunia, and Solanum.
  • Pomato is somatic hybrid between potato and tomato that belong to two different genera.
  • Protoplasts culture has opened up avenues for development of hybrids of even asexulally reproducing plants. Somatic> hybrids may be used for the production of useful allopolyploids.

Protoplasm Fusion

Applications of plant tissue culture

The various applications of plant tissue culture are:

  • The use of plant cells to regenerate useful products i.e. , a plantlets which is used for various purposes.
  • Plantlets are used for rapid clonal propagation.
  • Transgenes can be introduced into individual plant cells. The plantlets can be regenerated from these cells which give rise to the highly valuable transgenic plants.
  • For induction of mutations as genetic manipulations can be carried out more rapidly when plant cells are in protoplast state. New genes can be introduced(Ex: male sterility, herbicide resistance).
  • For raising stress resistant plants.

Chapter 14: Ecosystem

An ecosystem can be visualised as functional unit of nature, where living organsism interact among themselves and also with the surrounding physical environment. Ecosystem may small or large, may be terrestrial or aquatic. Forest, grassland and desert are some example of natural terrestrial ecosytem. Pond, lake, wetland, river and estuary are some example of natural aquatic ecosystems. Cropfield and an aquarium may also be considered as man-made ecosytems.

Question 1 : Define Ecosystem , stratification , and functions of ecosystem .
Answer :
Ecosystem: System where biotic and abiotic components interact together to produce various functions .
Stratification: Vertical distribution of different species occupying different levels .
Functions of ecosystem:

  • Productivity
  • Decomposition
  • Energy flow
  • Nutrient cycling.

Question 2 : Write about productivity and its various types ?
Answer : Productivity
: The rate of production is called productivity . Productivity is of two types :

  1. Primary productivity: Amount of biomass produced per unit area in a certain time period by plants through photosynthesis is primary productivity . It depends on following:

    1. Type of plant species.
    2. Photosynthesis capacity of plants .
    3. Nutrient availability .
    4. Availability of light , water ,etc

    GPP(Gross Primary Productivity) : Rate of production of organic matter during photosynthesis
    NPP(Net Primary Productivity) : It is the amount of GPP produced after excluding respiration and other losses.
    NPP = GPP – respiration

  2. Secondary Productivity: Secondary productivity is the rate of formation of new organic matter by the consumers . Ex : milk , meat , egg.


Decomposition is the process that concerns breakdown of complex organic matter by decomposers to inorganic raw materials like carbon dioxide, water and various nutrients. The upper layer of soil is the main site for decomposition processes in the ecosystem. The process of decomposition involves several processes. These processes can be categorised as fragmentation of detritus, leaching and catabolism. After these steps humification or mineralisation occurs. By humification humus formation take place. By mineralisation mineral formation take place.

Decomposition Cycle

Question 3: Explain in detail about Decomposition ?
Answer: Decompostion:
Process of breakdown of the organic matter present in detritus into inorganic substances like CO2, H2O. Detritus : dead decaying remains of plants and animals.
Detritivores: Organism which break large detritus particle into small particle are detritivores . Ex : earthworm , bacteria .
Steps of decomposition:

  1. Fragmentation : Detritivores break large detritus particle into small particles .
  2. Leaching : Water soluble inorganic nutrients go into soil horizon and get precipitated as unavailable salts .
  3. Catabolism : Bacterial and fungal enzymes degrade into inorganic substances .
  4. Humification : is accumulation of dark colored amorphous substance called humus . humus is resistant to microbial action and undergoes decomposition at very slow rate.
  5. Mineralisation : Humus is degraded by various enzyme and microbes release inorganic nutrients by mineralization process .

Fctors affecting decomposition :

  • Moisture availability : Decomposition fast in wet condition .
  • Warm temperature : Decomposition fast in warm temperature .
  • Chemical composition of detritus : decomposition is fast when detritus is rich in nitrogen and sugar and slower when detritus is rich in lignin and chitin .

Question 4: Write about Energy flow , food chain , food web , trophic level?
Answer: Energy flow:
There is a flow of energy through the ecosystem without its return. There is regular supply of energy from outside. Energy is dissipate at every level. Flow of energy is unidirectional.

Energy Flow

Food chain: A chain of organism in which one organism is eaten up by the other organism for flow of energy from one trophic level to another.
Example: Rat —– Snake —– Eagle.
Food web: Various interconnected food chain together form food web.
Trophic level: It is place in food chain where all organism have similar food habits .

Question 5: Write difference between primary and secondary succession ?
The difference between primary and secondary succession is :

Primary succession Secondary succession
Starts where no living organism ever existed takes place in an area that have lost all living organism s that existed there
Primary succession takes more time to complete secondary succession takes less time to complete
Ex : Bare, rock , lava ,etc Ex : Burnt forest , flooded area , cutted forest

Question 6: Write about ecological succession and terms related to it ?
Answer: Ecological succession :
The sequential , gradual and predictable change in a species composition of an area is called ecological succession . Primary and secondary successions are types of ecological successions.
Sere: Entire sequence of communities that successively change in a given area during biotic succession . Sere begins with pioneer community and ends in climax community.
seral stage: Individual transitional communities during succession. It is a stage between pioneer community and climax community .
Pioneer community: species that invade a bare area . It is the first community to colonise an area .
Climax community: It is the final community to develop over an area the area is already covered by late successional community before the arrival of climax community it is near equilibrium with the enviorment

Question 7: Write about Hydrach succession in detail ?
Answer: Hydrarch succession:
takes place in wetter areas and the successional series progress from hydric to the mesic conditions . It consists of following steps:

  • Pioneer species are small phytoplankton's .
  • Pioneer species are replaced by submerged plant stage .
  • Submerged free floating plant stage : floating plant like lemma , azolla begin to appear with the rise in shallowness of the pond .
  • Reed swamp stage : shallowness incresese more , appearance of more plants .
  • Marsh Meadow stage : free water is changed to swampy land, the water plants give way to swampy plants such as sedges and rushes .
  • Scrub stage: herb , shrub appears profusely.
  • Forest stage: It is the climax community which consists of trees.

Hydrach Succassion

Chapter 10 : Microbes in Human Welfare

Besides macroscopic plants and animals, microbes are the major components of biological systems on this earth. Microbes are present everywhere in soil, water, air, inside our bodies and that of other animals and plants. Microbes are divers, they belongs to protozoa, bacteria, fungi, virus, viroids and prions. All microbes are not harmful, many microbes are useful to man in diverse ways. Some of the most important contributions of microbes to human welfare are discussed in this chapter.

Question 1: Describe the role of microbes in household products ?
The role of microbes in household products are:

  1. LAB(Lactic Acid Bacteria) and lactobacillus: Coagulates and partially digests the milk protein. Its importance:

    1. It converts milk into curd
    2. Increase nutritional quality by increasing vitamin-B12
    3. Check the disease causing microbes
  2. Toddy: Fermented sap from palms used as traditional drink in south India
  3. Dough: It is used for making dosa or idli and is fermented by bacteria or yeast(Saccharomyces cerevisiae)
  4. Swiss cheese: It have large holes due to production of large amount of co2 by bacterium Propionibacterium sharmanii
  5. Roquefort cheese: It is flavoured cheese produced by Penicillium roquefortii

Microbes In Industria Products

In industry, microbes are used to synthesise a number of products valuable to human beings. Beverages and antibiotics are some examples. Production on an industrial scale, requires growing microbes in very large vessels called fermentors.

Question 2: Write role of microbes in industrial fermentation ?
Fermented Beverages: Produced by Brewers yeast(Saccharomyces cerevisiae). The quality of fermented beverages depend on raw material(cereals, fruits) used and the processing done(with distillation- brandy, rum, whisky and without distillation- wine and beer)

Question 3: What are antibiotics ?
Antibiotics which are produce completely or partially by chemical synthesis, to stop the growth or destroy the micro-organisms. They are taken in low concentration. Ex- Penicillium, ofloxacin, erythromycin, ampilicin, amoxicillin, etc.

Question 4: Write chemical enzymes and other bioactive molecules ?
The chemical enzymes and other bioactive molecules are as follows: Microbes Types of microbes Product
1 Asperiligus niger fungus citric acid
2 Acetobacter aceti Bacteria Acetic acid
3 Clostridium butylicum Bacteria Butyric acid
4 Lactobacilius Bacteria Lactic acid
5 Streptococcus Bacteria Streptokinase
6 Trichoderma polysporum fungus Cyclosporin A
7 Monascus purpureus yeast Statin

functions of above products are: Product Function
1 Streptokinase It is used as clot buster to remove clots from the blood vessels from patients who have undergone myocardial infaction
2 Cyclosporin A It is used as immuno suppresive agent in organ transplant
3 Statin It is used as blood cholestrol lowering agent, it acts by competitively inhibiting enzyme responsible for synthesis of cholestrol
4 Lipase Are used in detergents because they are helpful in removing oily stains from laundry
5 Pectinase &protease Are used to breakdown pectins and protiens, these are present in the bottle fruit juices and also used to clearify the bottle of fruit juice

Sewage Treatment

A major component of urban wastewater is human excreta. This municipal wastewater is also called sewage. It contains large amounts of organic matter and microbes. Many of which are pathogenic. Before its disposal to the waterway, it is treated with primary and secondary treatment.

Sewage Treatment

Question 5: Differentiate between primary and secondary treatment ?
The difference between primary and secondary treatment is: Primary treatment Secondary treatment
1 It is a physical process It is a biochemical process
2 No decrease in BOD BOD decreases after treatment with aerobic bacteria
3 Sedementation and filtration are main process Digetion by aerobic and anerobic bacteria are the main processes
4 No bio gas and manure is produced Bio gas is formed due to anaerobic bacteria breakdown of organic waste and manure is formed 

Question 6: What is secondary treatment ?
It is a biological treatement:

  1. The primary effulent is passed into large aeriation tanks where aerobic microbes convert waste organic material into inorganic substances, thus decreases BOD
  2. When the BOD decreased, effulent is passed into settling tanks where bacterial flocs are allowed to sediment. This sediment is called activated sludge. A samll part of this sludge is used as inoculum in aeriation tanks.
  3. The major part of the activated sludge is pumped into large tanks called anaerobic sludge digesters where anaerobic bacteria digest the waste and produced biogas(mixture of methane, H2S and CO2).

Benefits of secondary treatement:-

  1. Biogas formed which is used as fuel
  2. Remaining waste from anaerobic bacteria digesters is used as manure in fields.

Question 7: Explain the role of microbes in biogas production and its importance ?
Methanogens: These are bacteria which anaerobically breakdown cellulosic material to produce methane along with H2S and CO2(Ex: methanobacterium: they occur in the rumen of cattle, sheep, etc). Methanogens have the following importance:-

  1. Methanogens convert animal waste and plant waste into methane gas which is inflammable gas and used as a clean fuel.
  2. The waste left is used as manure which increases the soil fertility for the crop production.

Question 8: Explain the structure of biogas plant?
Biogas plant consists of a concrete tank(10-15 feet deep) in which bio waste are collected and a slurry of dung is fed. A floating cover is placed over the sluury which keeps on rising as the gas is produced in the tank due to the microbial activity. The biogas plant has an outlet, which is connected to a pipe to supply biogas.
Question 9: Explain the role of microbes as biocontrol agents ?
Biological control involves use of organisms to control pests or insects. These are target specific and do not harm other plants and animals. Following are the examples of biological control agents:

  1. Beetle with red and black marking: The ladybird and dragonflies are used to get rid of aphids and mosquitoes.
  2. fungus Trichoderma: These are free living fungi which is used as biocontrol agents of several plant pathogens.
  3. Baculovirus: These are pathogens that attack insects and other arthropods, baculovirus used as biolgical control agents in the genus Nucleopolyhedrovirus.
  4. Bacilius thuringinesis bacteria: It kill the caterpillar which feeds on Brassica, fruit trees, etc.

Question 10: Who were the scientists who discovered antibiotics Penicilin? Answer:Alexander Fleming, Ernst Chain and Howard Florey got nobel prize for discovery of antibiotics Penicilin. Penicilin is the first antibiotics obatained from fungiPenicilin notatum by Alexander when he was working with Staphylococci bacteria.
Question 11: Explain the role of microbes as bio-fertilisers?
Bio-fertilisers: Those organisms which provide nitrogen and phosphorus nutrient and also enrich quality of the soil. Example:

  • Bacteria(free living): Azospirilum and azotobacter
  • Bacteria(Symbiotic): Rhizobium
  • Fungi: Mycorizha: is an association between fungi and roots of higher plants(genus: glomus). Fungi increases surface area of roots for absorption of the water and minerals. Fungi provides inorganic nutrients to plant and plant gives organic food to fungi.
  • Cynobacteria: It is a blue green algae and they are biofertilisers and acn fix atmospheric nitrogen and provide them to plants, Ex: Anabena, nostoc and oscillatoria.

Biogas and Biogas Plant

Biogas is a mixture of methane (CH4) and carbon dioxide (CO2) produced anaerobically during a two stage bacterial breakdown of organic material. The excreta (dung) of cattle, commonly called gobar, is rich in these bacteria. Dung can be used for generation of biogas. Biogas production takes place in biogas plant.

Biogas plant

Chapter 15 : Biodiversity And Its Conservation


Biodiversity is a term used to describe all aspects of biological diversity, especially including species richness, ecosystem complexity, and genetic variations. In this chapter we study to find answers of some of questions such as: Why are there so many species? Did such great diversity exist throughout earth's history? How did this diversification come about? How and why is this diversity important to the biosphere? Would it function any differently if the diversity was much less? How do humans benefit from the diversity of life?

Types of Biodiversity

Question 1: What is biodiversity ?
The diversity found in the living organism is called bio diversity . This term was given by Edward Wilson . There are three types of biodiversity in nature:

  1. Genetic diversity: Diversity at the gene level is called genetic diversity. Ex: Rauwolfia vomitoria growing in Himalayan ranges shows genetic diversity in terms of potency and concentration of reserpine chemical .
  2. Species diversity: Diversity at the species level is called species diversity. Ex: Western Ghats have a greater amphibian species diversity than the Eastern Ghats .
  3. Ecological diversity: Diversity at the ecosystem level is called ecosystem diversity. Ex: India nation has a rich ecological diversity as it has deserts, rain forests, mangroves, wetlands, coral reefs, etc.

Alfa, Beta and Gamma Diversity

  1. Alfa Diversity (niche Diversification): Alpha diversity indicates diversity within the community. It refers to the diversity of organisms sharing the same community or habitat.
  2. Beta Diversity (habitat diversification): Beta diversity indicates diversity between communities. It is due to replacement of species with change in the habitat.
  3. Gamma Diversity (regional diversification): Gamma diversity refers to the diversity of the habitats over the total landscape or geographical area.


Question 2: What is longitudinal gradient and factors effecting it?
Answer :
Longitudinal gradient : Species diversity as we move from equator region to polar region . Tropical region has more diversity than temperate or polar region, because of following factors which effect it are:

  1. Speciation: Is a function of time, tropical region remain undisturbed for millions of the years, so have long time for speciation which results in rich biodiversity. Temperate region is subjected to frequent glaciations so, less time for speciation which results in less biodiversity.
  2. Tropical region is more constant and more predictable than temperate region , thus constant environment promote more biodiversity.
  3. Tropical region revives more solar energy , thus have higher productivity which results in more biodiversity.

Question 3: What is species area relationship ?
Answer :
Species area relationshipSpecies area relationship was given by Alexander Von Humboldt , within a region species richness increases with increase in area explored only up to limit . The relation between species richness and area explored turns out to be a rectangular hyperbola . On a logarithmic scale the relationship is straight line and described by the equation :
Log S = Log C + Z Log A .
Where S = species richness
A = area explored
Z = slope of the line
C = Y – intercept .
The value of Z lies in the range of 0.1 to 0.2 . The slope of the line is more steeper if the value of z is upto 1.6 , in large are like tropical area like tropical rain forest which has rich biodiversity .

Question 4: What is importance of species diversity to the ecosystem ?
Answer :
The Importance of species diversity to the ecosystem are :

  1. Community more species are more stable
  2. Community with more species show resistant or resilient to occasional disturbances
  3. Community with more species are resistance to invasion by alien species
  4. Stable community do not show too much variation in the productivity from year to year

Note : Experiment by David Tilman shows increased diversity contributed to higher productivity .

Question 5: What is Rivet Popper Hypothesis ?
Answer :
It was given by Paul Ehrlich. He compared aeroplane with ecosystem and rivets with species. According to him if every passenger starts popping a rivet from aeroplane, it may not effects flight safety initially but as more and more numbers of rivets are removed , the flight of aeroplane becomes dangerous for the ecosystem functioning.
Similarly , species extinction at initial level does not effect functioning initially but later on it may become dangerous for the functioning of ecosystem . Loss of rivets on the wings (Key stone species that drive major ecosystem function) is more dangerous for the flight (ecosystem ).

Question 6: What are causes of biodiversity losses (The Evil Quartet) and effects of loss of biodiversity ?
Answer :
The causes of biodiversity losses are:

  1. Habitat loss and fragmentation: When the habitat of flora and fauna is damaged, biodiversity decreases. Tropical rain forest covers more than 14% of the land surface but now only 6% due to deforestation. Amazon rain forest (lungs of the planet Earth as it releases 20% of oxygen ) is cut and cleared for cultivation of soybeans or converted to grasslands for raising beef cattle.
  2. Over Exploitation: Human need turns to greed leads to over exploitation of the natural resources. Ex: Stellar sea cow , passenger pigeon were extinct due to over exploitation by humans.
  3. Aliens species invasion: When species become invasive after their introduction, decline or extinct many native species. Ex: Carrot grass (parthenium), Lantana, and water hyacinth are invasive species .
  4. Co-extinction: When a species become extinct, the plant and animals species associated with it also become extinct. Ex: When a host fish become extinct all parasites dependent on it become extinct.

The effects of loss of biodiversity are:

  1. Decline in plant production.
  2. Lowered resistance to environmental perturbations such as droughts.
  3. Increased variability in certain ecosystem processes such as plant productivity, water use and pest-disease cycle.

Question 7: What are methods of biodiversity conservation ?
Two methods of biodiversity conservation are:

  1. In situ conservation: This is the conservation of biodiversity in their natural habitat, so along with biodiversity the habitat is also protected. Types of in situ conservation are:

    • Biodiversity hotspot: 34 (25 + 9) hotspots in the world. Hotspots are bio geographical region with rich biodiversity which are declared sensitive due to direct or indirect influence of the human activities. They have endemic (species confined to that region and not found anywhere else ) species. Eastern Himalayas and western Ghats are hotspots of India.
    • Protected areas: India has 14 biosphere reserves, 90 national parks and 448 wildlife sanctuaries . Jim Corbett National Park was the first to be established in India.
    • Ramsar sites: There are 26 ramsar sites in India. Ramsar sites are protected wetlands areas. Ex: Sambhar lake, chilika lake are protected wetlands.
    • Scared groves: Groves are protected by the native people due to their diversity and cultural importance. Ex: Khasi and jantia hills in Meghalaya , Aravali hills in Rajasthan, western Ghats of Karnataka and Maharashtra and Sarguja, Chand bastar areas of Madhyapradesh
  2. Ex situ conservation: (off site conservation ) It is the conservation of selected threatened plants and animals species in place outside their natural habita . Ex: Botanical gardens, Zoological parks, gene banks, etc.

Note: By using cryopreservation (preservation at -1960C in liquid Nitrogen) techniques sperm, eggs, animal cells, tissues and embryos can be stored for long period in gene bank, seed bank etc.

Question 8 : Why do we conserve biodiversity ?
Answer :
We should conserve biodiversity due to following utilities :

  1. Narrow Utility : Humans get economic benefits from nature like food, firewood, fibre, tannins, dyes, medicines (25% of drugs from plants) and many more uses.
  2. Broad utility : Biodiversity plays an important role in many ecosystem services that nature provides us like oxygen (Amazon forest produces 20% of the total oxygen in atmosphere through photosynthesis), pollination, etc.
  3. Ethical Utility : Philosophically and spiritually every species has an intrinsic value so we have moral duty to take care of them and pass them to next generation in good condition .
  4. Cultural Utility : Biodiversity has cultural value, it is a source of inspiration to poets, and writers. It gives cultural identity in terms of festivals and rituals .
  5. Religious Utility : Some plants like tulsi and peepal some animals like cow, monkey have religious importance described in scriptures .

Question 9 : state use of biodiversity in modern agriculture ?
Answer :
Agrochemicals cause pollution of soil and water and are too expensive. Genetic modification has made crops more tolerate to abiotic stresses like cold , heat, salinity,etc . It has reduced the dependence of crops on chemical pesticides as they are pest resistant .

Question 10 : What are exotic species ?
Answer :
Species that are not naturally found in the habitat , they are mostly introduced in a habitat from outside and they may become invasive too.

Question 11 : What are the specific objectives of conservation of wildlife ?
Answer :
The objectives of conservation of wildlife are :

  1. To maintain essential ecological processes and life supporting systems (air , water and soil )
  2. To preserve the diversity of species for their continuous use for future generations.

Question 12 : Which type of conservation measures, in situ or ex situ will help the larger number or species to survive ? Explain .
Answer :
In in situ conservation species are conserved in their natural habitats so the entire ecosystem along with other organism , biotic and abiotic component of the ecosystem associated with the target species are also conserved so in situ will help the larger number of species to survive .

Question 13 : There are many animals that have become extinct in the wild but continue to be maintained in zoo,
           1. What type of biodiversity conservation is observed in this case ?
           2. Explain two ways which help in this type of conservation ?
Answer :
1. It is an example of ex situ conservation, in which threatened plants and animals are take out of their natural habitat and placed in to suitable and given given special care.
2. Cryopreservation and tissue culture are two ways that help in ex situ conservation. In cryopreservation, gametes of threatened species are preserved in viable and fertile condition at sub zero temperatures, which help in preserving these cells for longer time. In tissue culture plants are propagated from a small mass of tissue called callus.

NEET Questions Based on Biodiversity and Conservation

NEET Questions Based on Biodiversity and Conservation

NEET Questions Based on Biodiversity and Conservation. Collections of Questions of previous year paper and their answers.

1. Which one of the following is related to ex situ conservation of threatened animals and plants?
(a) Biodiversity hotspots
(b) Amazon rainforest
(c) Himalayan region
(d) Wildlife safari parks

2.Alexander von Humboldt described for the first time.
(a) laws of limiting factor
(b) species area relationships
(c) population growth equation
(d) ecological biodiversity.

3. The region of biosphere reserve which is legally protected and where no human activity is allowed is known as
(a) buffer zone
(b) transition zone
(c) restoration zone
(d) core zone.

4. How many hotspots of biodiversity in the world have been identified till date by Norman Myers?
(a) 17
(b) 25
(c) 34
(d) 43

5. Which of the following is correctly matched?
(a) Aerenchyma and Opuntia
(b) Age pyramid and Biome
(c) Parthenium and Threat to hysterophorus biodiversity
(d) Stratification and Population

6. Red list contains data or information on
(a) all economically important plants
(b) plants whose products are in international trade
(c) threatened species
(d) marine vertebrates only.

7. Which of the following national parks is home to the famous musk deer or hangul?
(a) Keibul Lamjao National Park, Manipur
(b) Bandhavgarh National Park, Madhya Pradesh
(c) Eaglenest Wildlife Sanctuary, Arunachal Pradesh
(d) Dachigam National Park, Jammu and Kashmir

8. Which is the national aquatic animal of India?
(a) Blue whale
(b) Sea­horse
(c) Gangetic shark
(d) River dolphin

9. Which of the following is the most important cause of animals and plants being driven to extinction?
(a) Habitat loss and fragmentation
(b) Co­extinctions
(c) Over­exploitation
(d) Alien species invasion

10. The species confined to a particular region and not found elsewhere is termed as
(a) endemic
(b) rare
(c) keystone
(d) alien.


Kingdom-Plantae includes eukaryotic, autotrophic or photosynthetic and non-motile organisms. They have well defined cellulosic cell wall. Plastids are present. Plant kingdom include five major plant groups i.e., Algae, Bryophyta, Pteridophyta, Gymnosperms and Angiosperms as proposed by R.H. Whittaker.

Characteristics Feature Of Kingdom-Plantae

  1. This kingdom includes plants which are multicellular eukaryotes.
  2. All plants contain plastids. Plastids are double membrane organelle that posses photosynthetic pigments. They are called chloroplasts.
  3. They are usually autotrophic. Chloroplast contains a green colour pigment called chlorophyll and prepares its own food by the process of photosynthesis.
  4. The cell walls possess mainly cellulose.
  5. The plant body may be thalloid or differentiated into root, stem and leaves.
  6. They may be non-vascular or vascular.
  7. They have two stages in their life cycle- a haploid and a diploid. Haploid stage is sexually reproducing gametophytic generation and diploid stage is asexually reproducing sporophytic generation. The two generation alternate. This is called alternation of generation.

Classification Of Kingdom-plantae

Classification of Kingdom-plantae has many levels.
  1. Differentiation of plant body parts.
  2. Presence of Vascular System
  3. Presence of seed
  4. Covering of seed
  5. Number of Cotyledons.



1. Algae
2. Bryophyta
3. Pteridophyta
4. Gymnosperm
5. Angiosperm
6. Plant Life Cycles and Alternation of Generations

Chapter 5: Principles of Inheritance and Variation


Branch of biology which deals with the study of heredity and variations. Study of heredity involves the mechanism by which characters pass from parents to offspring. Study of variations involves cause of heredity.

  • Father of Genetics: G. Mendel
  • Father of Modern Genetics: W. Bateson
  • Father of Experimental Genetics: Morgan
  • Father of Human Genetics and Biochemical Genetics: A. Garrod

Some Important Terms

Chromosome: The nucleoprotein structure which are generally more or less rod-like during nuclear division. The genes are arranged on the chromosomes in a linear fashion. Each species has a characteristic number of chromosomes.

Gene: The fundamental physical and functional unit of heredity, which carries information from one generation to the next. It is a segment of DNA. Mendel called them factors. Johannsen coined term 'gene'.

Allele: Alternative forms of a gene which are located on corresponding positions on homologous chromosomes. Alleles are gene controlling the same characteristic but producing different effects. They occupying corresponding positions on homologous chromosomes.

Homozygous: The organism having two similar genes for a particular character in a homologous pair of chromosomes is known as homozygous or genetically 'pure' for that particular character. Example: TT, RR, AA etc.

Heterozygous: An individual containing both dominant and recessive genes or traits or characters of a allelic pair is known as heterozygous. Example: Tt, Rr, AB etc. Term  homozygous and heterozygous are coined by Bateson.

Acquired Character: The alteration in the morphology or physiology of an organism in response to its ecological or environmental factors. These characters are usually not heritable.

Cross: The deliberate mating of two parental types of organisms in genetic analysis. Cross can be monohybrid, dihybrid or trihybrid. Individual produced by cross is known as hybrid.

Genotype: The genetic constitution or genetic make up of an organism for a particular character.

Phenotype: It is the external and morphological appearance of an organism for a particular character.


  1. Mendelian Inheritance
  2. Inheritance of One Gene
  3. Inheritance of Two Gene
  4. Mendel's Law of Inheritance
      (a)Law of Dominance
      (b)Law of Segregation
      (c)Law of Independent Assortment
      (d)Exception of Mendelian Inheritance
  5. Chromosomal Theory of Inheritance
  6. Sex Determination
  7. Mutation
  8. Genetic Disorders

Mendelian Inheritance

Gregor Johann Mendel was the pioneer of classical genetics. He was born in July 22, 1822 in Heinzendorf in Austrian Silesia. Mendel worked in Augustinian monastery as monk at Brunn city, Austria.Beside his other duties, he took keen interest in natural sciences. From 1851 to 1853, he studied mathematics and natural science in the university of Vienna. In 1856-57, he started his experiments of heredity on pea (Pisum sativum) plant. His experimental worked continued on pea plant till 1865. (Duration of work is 1857-1865). The results of his experiments were published in the science journal by name of "Experiments on plant hybridisation". Mendel was unable to get any popularity. No one understood him. He died in 1884 without getting any credit of his work. After 16 years of Mendel's death in 1900, Mendel's postulates were rediscovered.

Rediscovery of Mendelism

Mendel's research paper remained dormant and unnoticed by the scientific world until 1900. There three botanists who rediscover mendel's postulation. They republished Mendel's original paper in 1901 in Flora magazine. Bateson confirmed Mendel's work by a series of hybridization. Re-discoverer were:

  • Carl Correns (Germany) worked on Maize
  • Hugo deVries (Holland) worked on Evening Primerose
  • Erich von Tschermak (Austria) worked on different flowering plants.

Question 1: What is inheritance and heredity?
The process by which characters are transferred from one generation to another generation is called inheritance and phenomenon is heredity.

Question 2: Explain Mendel's experiment in detail?
Gregor Johann Mendel(1822-1884) Father of genetics. Mendel performed his experiments with garden pea plant(Pisum sativum) and he selected pea because of following reasons:

  • Annual, short life span.
  • Easily available, maintained and raised easily.
  • Seven characters he selected were easily identified.
  • He observed one trait at a time.
  • Pea plant can easily self pollinated as the pea plant is bisexual plant.
  • Pea plant can also cross pollinated.

Reasons for success of Mendel:

  • Controlled pollinated as pea can both cross and self pollinated easily.
  • He used true breeding pea plant.
  • He kept record of his breeding experiments.
  • Analysed results by using law of probability.
  • Traits selected by him does not show interaction like incomplete dominance, linkage.

Question 3: Why work of Mendel does not recognized initially?
The work of Mendel was not recognized because of following reasons:

  1. His work was ahead of his time.
  2. Journals in which his work published had limited circulations.
  3. He failed to get similar result in Hawkweed.
  4. Mathematical approach in working out biological problems was strange to others.
  5. Minds of biologists were preoccupied with Darwin's theory of evolution.

Question 4: Explain about the following 1)Genes 2)Alleles 3)Dominant 4)Recessive ?
1)Genes: These are the units of inheritance. They contain the information that is required to express a particular trait in an organism.
2)Alleles: Genes which codes for a pair of contrasting traits are known as alleles i.e. they are slightly different forms of same gene(T and t).
Dominant: Characters which can express itself in both homozygous and heterozygous conditions.
4)Recessive: Characters which only express themselves in homozygous condition and remain masked in heterozygous condition.

Question 5: Explain laws of Mendel?
Mendel gave three laws on inheritance based on hybridization experiments, Three laws are as follows:

Inheritance of One gene

The Cross between the pea plants differing in single pair of contrasting characters is known as monohybrid cross. Mendel called the original parents the P Generation and the first generation offspring the F1 (filial first) Generation. The second generation offspring is known as F2 (filial second) Generation. F1 generation is obtained by cross fertilization while F2 generation is obtained by self fertilization. Phenotype ratio 3:1 and genotype 1:2:1.

Monohybrid Cros

Inheritance of Two gene

The Cross between the pea plants differing in two pair of contrasting characters is known as dihybrid cross. When a dihybrid cross between pea variety having yellow cotyledons and round seed with another variety having geen cotyledons and wrinkled seeds was done, the F1 seeds were yellow and round. In second generation phenotypic ration is 9:3:3:1 ratio. Genotypic ratio is 1:2:2:4:1:2:1:2:1.

Dihybrid Cros

  1. Law of Dominance: This law states that when two alternative forms of a character are present in an organism only one factor expresses itself which is called as dominant while the other that remains masked is called recessive.
  2. Law of Segregation: This law states that factors or alleles of a pair segregate from each other during gamete formation such that a gamete receive only one factor. They do not show blending. This law is also known as law of purity of gametes.
  3. Law of Independent Assortment: When two pairs of traits are combined in a hybrid, inheritance of one pair of characters is independent of the other pair of characters.

Sex Determination

Sex DeterminationSex determination is the method by which the determination between males and females is established. Sex determination may be chromosomal, cytoplasmic, Environmental and Genic balance mechanism. The genetic or chromosomal mechanism of sex determination is based on occurenece of two types of gametes, means on the basis of set of chromosome in zygote.
Male heterogamety: Means male produces two types of gametes(X or Y and X or O).
1. XX-XY- type (Ex- Human beings, Drosophilla)
2. XX-XO type (Grasshopper, cockroach)
Female heterogamety: Female produces two types of gametes(Z or W and Z or O)
1. ZZ-ZW type (Birds, reptiles)
2. ZZ-ZO type (Moths)
Haploid-diploid sex determination: In honey bees males are haploid having 16 chromosomes and the develop by the process of mitosis cell division and female are diploid having 32 chromosomes and they develop by meiosis division to form female gamete. Ex- Honey bee .

Fertilisation and Implantation


Fertilisation is the fusion of a haploid male gamete (sperm) and haploid female gamete (ovum) to form a diploid zygote. In human internal fertilisation take place. Fertilisation is a process that: (i) Restore diploid number of chromosomes (ii) Determine sex of the new organism (iii) Activation of zygote to start a series of mitotic divisions called cleavage.

During copulation (coitus) semen is released by the penis into the vagina, it is known as insemination. The motile sperms swim rapidly, pass through the cervix, enter into the uterus and finally reach the ampullary region of the fallopian tube. So fertilisation take place in ampulla of fallopian tube. The ovum released by the ovary is also transported to the ampullary region where fertilisation take place. Fertilisation can only occur if the ovum and sperm are transported simultaneously to the ampullary region. This is the reason why not all copulations lead to fertilisation and pregnancy.

Fertilisation and Implantation

Events of Fertilisation

The process of fusion of a sperm with an ovum is called fertilisation. During fertilisation, a sperm comes in contact with the zona pellucida layer of the ovum and induces changes in the membrane that block the entry of additional sperms. Thus it enusres that only one sperm can fertilise an ovum. The secretions of the acrosome help the sperm enter into the cytoplasm of the ovum through the zona pellucida and the plasma membrane. This induces the completion of the meiotic division of the secondary oocyte. The second meiotic division is also unequal and results in the formation of a second polar body and a haploid ovum (ootid). Soon the haploid nucleus of the sperms and that of the ovum fuse together to form a diploid zygote. All this process can be grouped into following reproductive events:
(1) Acrosomal Reaction
(2) Cortical Reaction
(3) Sperm Entry
(4) Karyogamy
(5) Activation of Egg

Significance of Fertilisation

  1. Fertilisation provides stimulus to the egg to complete its maturation.
  2. Fertilisation activates the ovum to develop into a new individual by repeated mitotic divisions.
  3. Fertilisation restores the diploid number of chromosomes, characteristic of the species (46 in humans), in the zygote.
  4. Fertilisation combines the characters of two parents. This introduces variations, which make the offsprings better equipped for the struggle for existence and contribute to evolution of the race.
  5. Fertilisation determines the sex of the young one to be developed from the zygote in humans.
  6. Fertilisation membrane developed after the entry of the sperm prevents the entry of additional sperms into the ovum.
  7. Fertilisation introduces centrioles which are missing in the ovum.


Cleavage is the rapid mitotic division in the fertilised egg. Cleavage begins almost immediately after fertilisation and continues during its passage down the fallopian tube to the uterus. During cleavage the embryo does not increase in size. The cells produced do not grow after division. The embryo with 8-16 solid ball of cells is called morula. Cells of morula is called blastomeres.


The morula continues to divide and transforms into blastocyst. The blastomeres in the blastocyst are arranged into an outer layer called trophoblast and an inner group of cells attached to trophoblast called the inner cell mass. The inner cell mass is the source of embryonic stem cells from which all body structures are formed. The inner cell mass looks like a knob at one pole. It is called embryonal knob. The cells of trophoblast which are in contact with the inner cell mass (embryonal knob) are known as cells of Rauber. Blastocyst contain a fluid filled cavity, known as Blastocoel.

Role of zona pellucida

After the formation of blastocyst, zona pellucida becomes thinner and finally disappears. The function of the zona pellucida is to prevent the implantation of the blastocyst at an abnormal site. It does not expose the sticky and phagocytic trophoblast cells till the blastocyst reaches the proper implantation site.


Implantation is the process by which the developing attaches itself to the wall of the mother's uterus and stimulates the development of the placenta. At the time of implantation embryo is present in form blastocyst. So Implantation is the attachment of blastocyst to the uterine wall (in endometrium). It take place about 7 days after fertilisation. With implantation, pregnancy is established. During implantation trophoblast layer gets attached to the endometrium and the inner cell mass gets differentiated as the embryo. After attachment, the uterine cells divide rapidly and covers the blastocyst. As a result, the blastocyst becomes embedded in the endometrium of the uterus. This is completion of implantation.Implantation

Menstrual Cycle (Reproductive Cycle)

Menstrual cycle is the cyclic change in the reproductive tract of primate females, including human, apes and monkeys. The cyclical changes in the ovary and the uterus during menstrual cycle are induced by changes in the levels of pituitary and ovarian hormones. Menstrual cycle in human female starts at the age of 12-15 years and continues upto the age of 45 years. Menstrual cycle is absent during pregnancy, may be suppressed during lactation and permanently stops at menopause. First menstruation is called menarche and last menstruation is called menopause. In human duration of menstrual cycle is 28 days.

Phases of Menstrual Cycle

The menstrual cycle consists of 3 phases:
1. Follicular phase (Proliferative phase/ preovulatory phase)
2. Luteal phase (Secretory phase/ post ovulatory phase)
3. Menstrual phase (Bleeding phase)

Menstrual Cycle

Menstrual phase

The cycle starts with bleeding phase in its first 3 to 5 days. During this bleeding the part of the layer of endometrium gets shed off. The menstrual flow is a liquid that contain endometrial lining of the uterus, blood. It comes out through vagina. Menstruation only occurs if the released ovum is not fertilised. Lack of menstruation may be indicative of pregnancy. However, it may also be caused due to some other causes like stress, poor health etc. Menstrual fluid contains fibrinolysin, so it doesn't clot.

Proliferative phase

During this phase, the primary follicles in the ovary grow to become a fully mature Graafian follicle and simultaneously the endometrium of uterus regenerates through proliferation. The secretion of gonadotropins (LH and FSH) increases gradually during the follicular phase, and stimulates follicular development as well as secretion of estrogens by the growing follicles. Both LH and FSH attain a peak level in the middle of cycle (about 14th day). Maximum level of LH during mid cycle is called LH surge. LH surge induces rupture of Graafian follicle and thereby the release of ovum (Ovulation).

Luteal phase

During this remaining parts of the Graafian follicle transform as the corpus luteum. The corpus luteum secretes large amounts of progesterone which is essential for maintenance of the endometrium. Such an endometrium is necessary for implantation of the fertilised ovum and other events of pregnancy. During pregnancy all events of the menstrual cycle stop and there is no menstruation. In absence of fertilisation, the corpus luteum degenerates. This causes disintegration of the endometrium leading to menstruation, marking a new cycle.

DRGP Special Points

  • Progesterone is known as pregnancy hormone, it is important to maintain the pregnancy.
  • The time period between ovulation and next menstrual bleeding is always constant.
  • Ovulation occurs at 14th day (mid cycle). In this stage both LH and FSH attain a peak.
  • Menstrual fluid contains fibrinolysin, so it doesn't clot.

Seed and Fruit

Seed and fruit are post fertilisation structures in flowering plants. Seed is developed from ovule and fruit is developed from ovary. Following transformation take place after fertilisation:

Seed and Fruit


In angiosperms, the seed is the final product of sexual reproduction. It is often described as a fertilised ovule. Seeds are formed inside fruits. A seed typically consists of seed coat(s), cotyledon(s) and an embryo axis. The cotyledons of the embryo are simple structures, generally thick and swollen due to storage of food reserves (as in legumes).

Integuments of ovules harden as tough protective seed coats. The micropyle remains as a small pore in the seed coat. The facilitates entry of oxygen and water into the seed during germination. As the seed matures, its water content is reduced and seeds become relatively dry (10-15 per cent moisture by mass). The general metabolic activity of the embryo slows down. The embryo may enter a state of inactivity called dormancy, or if favourable conditions are available (adequate moisture, oxygen and suitable temperature), they germinate.

Question: What is perisperm?
In some seeds such as black pepper and beet, remnants of nucellus are also persistent. This residual, persistent nucellus is the perisperm.

Type of Seeds

Mature seeds may be non-albuminous or albuminous. Non-albuminous seeds have no residual endosperm as it is completely consumed during embryo development (e.g., pea, groundnut, sunflower). Albuminous seeds retain a part of endosperm as it is not completely used up during embryo development (e.g., wheat, maize, barley, castor).

Importance of Seed

  • Seeds can remain dormant for many years and germinate on return of favourable conditions.
  • Seeds have better adaptive strategies for dispersal to new habitats and help plant species to be colonized in different areas.
  • Seeds have sufficient food reserves to initiate embryo development and seedling development till the photosynthesis process is initiated.
  • Hard seed coat insure protection to the young embryo from environment stress.
  • Can be easily stored for future usage Long term viability of most of the seeds.
  • Seeds are the product of sexual reproduction it promotes diversity.


As ovules mature into seeds, the ovary develops into a fruit, i.e., the transformation of ovules into seeds and ovary into fruit proceeds simultaneously. The wall of the ovary develops into the wall of fruit called pericarp. The fruits may be fleshy as in guava, orange, mango, etc., or may be dry, as in groundnut, and mustard, etc. Many fruits have evolved mechanisms for dispersal of seeds.

Types of Fruit

True fruits

Fruits develop only from the ovary and are called true fruits. Example: Cucumber, tomato, coconut etc.

False fruits

When floral parts other than ovary, particularly thalamus contributes to fruit formation, such fruits are called false fruits. Example: apple, strawberry, cashew, etc., the thalamus also contributes to fruit formation. Such fruits are called false fruits.

False Fruit

Parthenocarpic fruits

Fruits develop without fertilisation. Such fruits are called parthenocarpic fruits and this process is known as parthenocarpy. It can be induced through the application of growth hormones and such fruits are seedless. Example: Orange, banana, water melon, grapes etc.