CBSE Class 12 Biology Strategies For Enhancement In Food Production Notes

Animal Breeding-objectives:

1.Improved growth rate.

2.Increased production

3. Improve desirable qualities.

4.Improved resistance to diseases

5.Improved resistance to adverse environmental conditions

Methods:

i).Inbreeding:-Breeding between same breed for 4-6 generations. Eg.- cows, buffaloes, poultry In breeding depression- continued in breeding reduces fertility even productivity. A single outcross often helps to overcome inbreeding depression

ii) Outbreeding- breeding between unrelated animals of two types –

1.) Out crossing- mating within the same breed but not having ancestors.

2.) Crossbreeding- superior males of one breed are mated with superior females of another breed to get better progency.e.g.- cows of inferior breed with superior bull. Hisardale- is a new breed of sheep developed in Punjab by crossing Bikaneri Eves and Marano Rams.

3) Interspecific hybridization- male and female animals of two different species are mated. E.g.- mule is crossbreed of male donkey and female horse.

4) Control breeding- it is done by artificial insemination and multiple ovulation embryo transfer technology (MOET)

(a)Artificial insemination- semen of superior male is collected and injected unto the reproductive tract of selected female. The spread of certain diseases can be controlled by this method.

(b) MOET- Technique for herd improvement by successful production of hybrids.

i) Hormone(FSH) are administered to the cow for inducing follicular maturation and super ovulation.

ii)Cow produces 6-8 eggs instead of one egg & is either mated with elite bull or artificially inseminated.

iii) Fertilised egg at 8-32 cell stage are recovered non-surgically & transferred to surrogate mother.

iv)IDone in cattle, sheep, rabbits etc.

Steps in Plant breeding:-

1 Collection of variability-Collection and preservation of all different wild varieties, species, relatives of cultivated species etc. are also called germplasm collection.

2.Evaluation and selection of parents-Germplasm is evaluated to identify plants with desirable traits.

3.Cross hybridization among the selected parents-Two plants having two desired characters are hybridized to get new hybrid having two desired characters.

4.Selection and testing of superior recombinants-Selection of the plants having desired character combinations.

5.Testing, release and commercialization of new cultivars-Newly selected lines are evaluated for their yield, agronomic traits, disease resistance etc. and released into the market.

Green revolution - Crop production.

White revolution - Milk production

Blue revolution - Fish production

Biofortification-Breeding crops with higher levels of proteins, vitamins and minerals eg. Vit C rich bitter gourd, mustard, tomato; protein rich beans lablab etc.

SCP (Single cell protein )- Protein rich cell biomass from microbes such as bacteria, yeast, algae are used as alternative food.

Eg-Spirulina can be grown in waste water (from potato processing plant) to produce protein rich biomass treated as food.

Advantages : i) Provides protein rich food supplement in human diet

ii) Reduces pressure of conventional agricultural production iii)Use of Waste water reduces pollution leveliv) High rate of biomass production in large amount in short period.

Tissue culture-

Technique of in vitro regeneration of whole plant by growing any plant part called explant in culture medium under aseptic condition. includes following methods:

1.Callus culture: Cell division in explant form an unorganized mass of cell called callus.

2. Suspension culture: Involves small group of cells suspended in a liquid media.

3..Meristem Culture –Apical shoot meristem is used as explant & support multiple shoot development.

4.Embryo Culture:Excision of young embryos from developing seeds & culture in nutritional media.

5.Anther culture:Production of haploid plant species by desired anther cultured in suitable medium.

6. Protoplast culture and somatic hybridization-

In this method, hybridization of different species could produce variants of economic value as follows:

i) Isolation of desired single cells 

ii) Digestion of cell wall by pectinase & cellulase enzyme for exposure of protoplast

iii) Fusion of protoplast by Polyethylene glycol(PEG) iv) Hybrid protoplast culture resulting in desired variety of plant eg., Pomato is obtained by somatic hybrid of potato and tomato.

7.Micropropagation-

Tissue culture technique used for rapid vegetative multilication of ornamental plants and fruit trees by using small explants. Micropopagation is done by shoot meristem culture & somatic embryogeny. It results in genetically identical plants & used widely in forestry & floriculture.
8.Somaclonal variation-Genetic variation in plants regenerated from a single culture is used to develop several useful varieties eg., Short duration sugarcane, Rust resistant wheat.
Uses: a)Rapid clonal multiplication
b)Production of virus free plants
c)Production of transgenic plants
d)Germplasm collection

IMPORTANT scientist and his contribution-Norman E Borlaug ---Developed semi dwarf variety wheat

IMPORTANT TERMS

1.MOET - MULTIPLE OVULATION EMBRYO TRANSFER TECHNOLOGY

2.SCP - SINGLE CELL PROTEIN

3. Breed: Group of animals similar in most of the characters and related in descent

4. Superior female: Cow or buffalo that produces more milk per lactation.

5 .Superior male: Bull that gives rise to superior progeny

6.somaclones – A group of plants that are genetically identical

Animal Breeding-objectives: 1.Increasing yield 2..To improve desirable qualities.

Methods: i).Inbreeding:-Breeding between same breed for 4-6 generations. Eg.- cows, buffaloes, poultry Inbreeding depression- continued in breeding increases homozygosity of harmful recesive genes.

METHODS TO OVERCOME INBREEDING DEPRESSION

ii) Outbreeding- breeding between unrelated animals of two types –

1.) Out crossing- mating within the same breed but not having ancestors.

2.) Crossbreeding- superior males of one breed are mated with superior females of another breed to get better progeny. eg.. Hisardale- is a new breed of sheep developed in Punjab by crossing Bikaneri Eves and Marino Rams.

3) Interspecific hybridization- male and female animals of two different species are mated. E.g.- mule is crossbreed of male donkey and female horse.

CONTROLLED BREEDING EXPERIMENTS

(a)Artificial insemination- semen of superior male is collected and injected unto the reproductive tract of selected female. The spread of certain diseases can be controlled by this method.

(b) MOET- Technique for herd improvement by successful production of hybrids.

Steps-MOET

i) Hormone(FSH) are administered to the cow for inducing follicular maturation and super ovulation.

ii)Cow produces 6-8 eggs instead of one egg & is either mated with elite bull or artificially inseminated. iii) Fertilised egg at 8-32 cell stage are recovered non-surgically & transferred to surrogate mother.

iv) Done in cattle, sheep, rabbits etc.

Bee keeping(apiculture) is the maintenance of hives of honey bees for production of honey and beeswax.

Important points of bee keeping
1.Knowledge of the nature and habits of bees
2.selection of suitable location for keeping the beehives
3.Catching and hiving of swarms
4.Management of bee hives during different seasons
5.Handling of honey and beeswax.

Fisheries: An industry devoted to catching ,processing or selling fish ,shellfish or other aquatic animals.

Types

1.Pisciculture: Breeding ,hatching and rearing of fish under controlled conditions
2.Aquaculture : Cultivating freshwater and saltwater organisms under controlled conditions
Plant breeding: It is the purposeful manipulation of plant species in order to create desired plant types that are better suited for cultivation ,give better yields and are disease resistant

Steps in Plant breeding:-

1 Collection of variability-Collection and preservation of all different wild varieties, species, relatives of cultivated species etc. It is also called germplasm collection.
2.Evaluation and selection of parents-Germplasm is evaluated to identify plants with desirable traits.
3.Cross hybridization among the selected parents-Two plants having two desired characters are hybridized to get new hybrid having superior characters. 
4.Selection and testing of superior recombinants-Selection of recombinant having desired character combinations.
5.Testing, release and commercialization of new cultivars-Newly selected lines are evaluated for their yield, agronomic traits, disease resistance etc. and released into the market.

Green revolution - Development in Crop production.
Blue revolution - Development in Fish production
Plant breeding for disease resistance : Breeding and development of cultivars resistant to diseases.

Advantages: Increased productivity, reduced dependence on use of fungicides and bactericides 

Types

1.Conventional breeding: Involves hybridization and selection.
Steps are - germplasm collection, screening the germplasm for disease resistance, hybridization, selection and evaluation of hybrids, testing and release of new varieties.

2.Mutational breeding It involves inducing mutations artificially through use of chemicals or radiations and selecting and using the plants that have desirable characters as source in breeding Eg. mung bean resistant to yellow mosaic virus and powdery mildew
: Limited number of disease resistant genes in crop varieties are in their wild relatives Eg. Parbhani kranti(bhindi) resistant to yellow mosaic virus.
Plant breeding for developing resistance to insect pests.
Insect resistance is due to morphological, biochemical or physiological characteristics of the crop variety .
Eg. 1.Hairy leaves offers resistance to insect pests like jassid
2.Solid stem in wheat resists attack by saw fly.
3. Smooth leaves and nectar rless condition resist cotton bollworms.
4.High aspartic acid ,low nitrogen and sugar content resists attack by stem borer(maize) Biofortification-Breeding crops with higher levels of proteins, vitamins and minerals eg., Vit A enriched carrots and spinach , Vit C rich bitter gourd, mustard, tomato; protein rich beans lablab etc. 
Eg. Atlas 66 Maize variety having high protein content Iron fortified rice SCP (Single cell protein )-

Protein rich cell biomass from microbes such as bacteria, yeast, algae are used as alternative food.

Eg-Spirulina can be grown in waste water (from potato processing plant) to produce protein rich biomass treated as food.
Eg. 250g Methylophilus methylotrophus produces 25 tonnes of protein
Advantages : i) Provides protein rich food supplement ii) Reduces pressure of conventional agricultural production iii)Use of Waste water reduces pollution level iv) High rate of biomass production in short period.

Tissue culture-
Technique of in vitro regeneration of whole plant by growing any plant part called explant in culture medium under aseptic condition. includes following methods:

1.Micropropagation-
Tissue culture technique used for rapid vegetative multilication of ornamental plants and fruit trees by using small explants. The process generates somaclones.

2.Meristem culture -helps in the recovery of healthy plants from diseased plant parts.

3 .Somatic hybridisation.-fusion of isolated protoplasts(cells without cell wall- naked cells) from two different varieties of plants. eg. Fusion of tomato and potato cells Crop varieties resistant to diseases

MCQ Questions

Question…… is the agricultural practice of feeding, breeding and raising livestock. Choose the most appropriate word to fill in the blank.
(a) Animal husbandry
(b) Cattle improvement
(c) Both (a) and (b)
(d) Cattle farming
Answer : A

Question. The term ‘breed’ refers to
(a) a group of animals not related by descent but similar in most characteristics
(b) a group of animals related by descent and similar in most characteristics
(c) a group of animals related by descent but have almost different characteristics
(d) a group of animals neither related by descent nor have similar characteristics
Answer : B

Question. The term ‘inbreeding’ refers to
(a) mating of more closely related individuals within the same breed for 4-6 generations
(b) mating of unrelated animals of the same breed
(c) mating of animals within the same breed, but having no common ancestors up to 4-6 generations
(d) superior males of one breed are mated with superior females of another breed
Answer : A

Question. Animal husbandry includes
(a) fisheries
(b) poultry farming
(c) dairying
(d) All of these
Answer : D

Question. Crustacean fishery is connected with exploitation of
(a) oysters and crabs
(b) mussels and squids
(c) shell and cuttle fish
(d) crabs and prawn
Answer : D

Question. The management of animals for milk and its products for human consumption is called
(a) dairy farming
(b) poultry farming
(c) white revolution
(d) livestock improvement
Answer : A

Question. In dairy farm management
(a) livestock improvement is done
(b) milk yield and quality is improved
(c) regular inspection of animals
(d) All of the above
Answer : D

Question. Choose the correct option.
(a) More than 70% of the world livestock population is in India and China
(b) The contribution of India and china to the world farm produce is about 25%
(c) Important livestock of India are cattle and buffaloes
(d) All of the above
Answer : D

Question. Which of the following qualities is considered for the selection of good breeds?
(a) High yielding potential
(b) Resistance to diseases
(c) Breed with pureline
(d) Both (a) and (b)
Answer : D

Question. What measures should be taken for cattles, to realise the yield potential?
(a) They have to be housed well
(b) Feeding should be in scientific manner
(c) Hygienic milking, storage and transport of milk
(d) All of the above
Answer : D

Question. Which of the following birds are domesticated in poultry farm management?
(a) Chicken
(b) Ducks
(c) Turkey and geese
(d) All of these
Answer : D

Question. Which of the following points should be kept into consideration for management of poultry farm?
A. Selection of disease free and suitable breeds
B. Proper and safe farm conditions
C. Proper feed and water
D. Hygiene and healthcare
(a) A,B,C
(b) A,C,D
(c) A,B,C,D
(d) None of these
Answer : C

Question. Bird flu is a ………… disease.
(a) viral
(b) bacterial
(c) fungal
(d) algal
Answer : A

Question. (Image 14)
Identify improved breed shown in diagram.
(a) A–Jersey, B–Leghorn
(b) A–Surti, B–Sangamneri
(c) A–Marwari, B–Sirohi
(d) A–Beetal, B–Jamunapari
Answer : A

Question. An infectious bacterial disease of cattle, buffaloes, sheeps and goats is
(a) anthrax
(b) rinderpest
(c) tick fever
(d) necrosis
Answer : A

Question. Which of the following is an aim of animal breeding?
(a) Increasing the yield of animals
(b) Improving the desirable qualities of the produce
(c) Producing better looking animals
(d) Both (a) and (b)
Answer : D

Question. Homozygous purelines in cattle can be obtained by 
(a) mating of related individuals of same breed
(b) mating of unrelated individuals of same breed
(c) mating of indviduals of different breed
(d) mating of individuals of different species
Answer : A

Question. Suggest a way to overcome inbreeding depression.
(a) Selected animals should be mated with related superior animals of different breed
(b) Selected animals should be mated with unrelated superior animals of same breed
(c) Selected animals should be mated with related superior animals of same breed
(d) Selected animals should be mated with unrelated superior animals of different breed
Answer : B

Question. Hissardale is a new breed of …A… developed in Punjab by crossing …B… and …C… .Here A to C refers to
(a) A–sheep, B–Bikaneri ewes, C–Marino rams
(b) A–chicken, B–Dorking, C–Sussex
(c) A–chicken, B–Leghorn, C–Plymouth rock
(d) A–cow, B–Jersey, C–Brown Swiss
Answer : A

Question. Interspecific hybridisation is the mating of
(a) animals within same breed without having common ancestors
(b) two different related species
(c) superior males and females of different breeds
(d) more closely related individuals within same breed for 4-6 generations
Answer : B

Question. Livestock refers to
(a) pet animals
(b) poultry and pet animals
(c) domestic animals which are kept for use or profit
(d) None of the above
Answer : C

Question. The practices concerned with the improvement in animal husbandry include
(a) management of farm and farm animals
(b) management of animals and plants at a same place
(c) genetic engineering
(d) None of the above
Answer : A

Question. A mule is produced by
(a) cross-breeding
(b) outcrossing
(c) inbreeding
(d) interspecific hybridisation
Answer : D

Question. Controlled breeding experiments are carried out using
(a) interspecific hybridisation
(b) artificial insemination
(c) outcrossing
(d) intraspecific hybridisation
Answer : B

Question. MOET stands for
(a) Multiple Ovulation Embryo Transfer technology
(b) Multiple Ovary and Embryo Transfer technology
(c) Multiple Ovulation Embryo Test technology
(d) Method of Egg Transfer
Answer : A

Question. Where Taichung Native-1 was developed?
(a) Taraiva
(b) Tokyo
(c) Tallinn
(d) Taiwan
Answer : D

Question. Jaya and Ratna are varieties of
(a) maize
(b) wheat
(c) rice
(d) millet
Answer : C

Question. In MOET procedure, to induce follicular maturation and superovulation which of the following hormones are administered to the cow?
(a) Follicle stimulating hormone
(b) Progesterone
(c) Androgen
(d) Oxytocin
Answer : A

Question. Saccharum barberi and Saccharum officinarum are varieties of
(a) sugarcane
(b) maize
(c) wheat
(d) rice
Answer : A

Question. The process by which genetic variations are created through changes in the base sequences within genes is
(a) plant breeding
(b) interspecific hybridisation
(c) outcrossing
(d) mutation
Answer : D

Very Short Answer Types Questions

Question. Millions of chicken were killed in West Bengal, Asom, Odisha and Maharashtra recently. What was the reason?
Answer : Millions of chicken were killed or rejected in West Bengal, Asom, Odisa and Maharashtra because they were found to be infected with H N 5 1 virus, which is the causal organism of bird flu.

Question. Can gamma rays used for crop improvement programmes prove to be harmful for health? Discuss.
Answer : No radiation treatment has been used to create thousands of new plant varieties. These varieties are cultivated as food and feed. Radiation is known to be much more disruptive for chromosomal structure than the manipulations used to make transgenic plants. Such radiation treatment of crop plants has caused no documented instances of ill-health among consumers despite having been used commercially for several decades. For rice crops alone, hundreds of different mutant varieties have been developed mostly made by using ionising radiations, like gamma rays.

Question. Why are proteins synthesised from Spirulina called single cell proteins?
Answer : Single cell proteins are proteins obtained from unicellular organisms/microorganisms. Spirulina is one such unicellular microbe. So, the proteins synthesised by Spirulina are called single cell proteins.

Question. A person who is allergic to pulses was advised to take a capsule of Spirulina daily. Give the reasons for the advise.
Answer : The person with allergies to pulses is advised to take Spirulina daily due to the following reasons (i) It could be a substitute for protein rich pulses. (ii) Spirulina is rich in beta-carotene and anti-oxidants besides all essential amino acids that help in improving the allergic symptoms appeared due to consumption of pulses.

Question. What is aquaculture? Give example of an animal that can be multiplied by aquaculture.
Answer : When culturing of aquatic plants and animals is done in freshwater bodies, it is called aquaculture. Examples of animals that can be multiplied by aquaculture are Finfish — Tilapia, Carp, Catfish, etc. Shellfish — Shrimps, Oysters, etc.

Question. Name a man-made cereal. Trace how it was developed and where is it used?
Answer : Triticale is a man-made cereal. It was developed by crossing Triticum aestivum (common wheat) and Secale cereale (European rye). Triticale seed grain is being used in some parts of the world as a wheat substituted.

Question. A few statements are given below followed by a set of terms in a box. Pick the correct term and write it against the appropriate statement
Answer : (a) Mating of closely related individuals within the same breed is called inbreeding.
(b) Mating of animals of same breed but having no common ancestors on either side for 4-6 generations is called outbreeding.
(c) Mating of animals of two different species is called interspecific hybridisation.
(d) Breeding of animals belonging to different breeds is called cross-breeding.

Question. What is meant by ‘hidden hunger’?
Answer : Consumption of food deficient in nutrients particularly, micronutrients, proteins and vitamins is called ‘hidden hunger’.

Question. Give two important contribution of Dr. MS Swaminathan.
Answer : Contributions of Dr. MS Swaminathan are as follows (i) Introduction of short, high yielding varieties of wheat in India.
(ii) Development of short duration, high yielding varieties of rice.

Question. The term ‘desirable trait’ can mean different things for different plants. Justify the statement with suitable examples.
Answer : The desirable trait can be different for different for different plants. The breeders have tried to incorporate these into crop plants.
The list may be as follows
(i) Increased tolerance to environmental stress (salinity, extreme temperature, drought) e.g., hybrid maize, jowar and bajra which are resistant to water stess.
(ii) Resistance to pathogens (viruses, fungi and bacteria) e.g., moong bean (resistance to yellow mosaic virus and powdery mildew).
(iii) Increased tolerance to insect pests. e.g., a new variety of Brassica (rapeseed mustard) is resistant to aphids.
(iv) High-yielding and improved quality of crop plant. e.g., Atlas 66 used as a donor for developing wheat varieties with improved protein content.

Question. Why are plants obtained by protoplast culture called somatic hybrids?
Answer : Plants obtained by protoplast culture are called somatic hybrids because they are formed by the fusion of isolated protoplasts from two different varieties of plants, each having a desirable character, to obtain a hybrid protoplast which can be further grown to form a plant. 

Short Answer Type Questions

Question. You are planning to set up a dairy farm. Describe the various aspects you would consider before you start the venture.
Answer : The following aspects are required to be considered (i) Good breeds with high-yielding potenital should be kept. (ii) Cattle should be fed in scientific manner with good quality and quantity of fodder. (iii) Animal shed should be kept clean, away from dirt and pollution. (iv) Cattle and handler should be kept in hygienic condition. (v) Regular visit by veterinary doctors with proper record is needed. (vi) Cattle should be housed well with adequate water and conditions should be disease-free.

Question. How can we improve the success rate of fertilisation during artificial insemination in animal husbandry programmes?
Answer : To improve chances of successful production of hybrids many means are used. One such programme is called MOET or Multiple Ovulation Embryo Transfer. During this procedure, a cow is given hormonal treatment so that more than one ovule (6-8 eggs) is produced per cycle. After mating or artificial insemination, the embryos at 8-32 celled state are transferred to different surrogate mothers. The method has been successfully used for cattle, sheep, buffalo, etc.

Question. What is meant by germplasm collection? What are its benefits?
Answer : The collection of all the diverse alleles of all the genes of a crop plant is called germplasm collection. It is of great benefits in plant breeding programmes as it offers, to the breeders, the entire of genes and alleles and the characteristics which a plant expresses. The breeder selects the most favourable characters of a particular gene, manipulates it and transfers to a desirable parent.

Question. Discuss briefly how pure lines are created in animal husbandry. K Thinking Process Inbreeding increases homozygosity.
Answer : When breeding is between animals of the same breed, it is called inbreeding. If we want to evolve a pureline in any animal, inbreeding (for 4-6 generation) is necessary. It also helps in accumulation of superior genes and elimination of less desirable genes by increasing homozygosity.

Question. What are the physical barriers of a cell in the protoplast fusion experiment? How are the barriers overcome?
Answer : Cell wall is the most important physical barrier in protoplast fusion experiments. This can be overcome by treatment with enzymes like cellulase and pectinase which have the ability to digest the cell wall and liberate the naked protoplast surrounded only by the cell membrane.

Question. Give few examples of biofortified crops. What benefits do they offer to the society?
Answer : Maize, wheat, rice, bathua, spinach, pulses have biofortified varieties. Maize hybrids have twice the amount of amino acids, fortified wheat variety has high protein content, fortified rice has high quantity of iron. Consumption of such biofortified foods will enrich the nutritive value of our common foods and will vastly improve public health. Instead of consuming different food items for obtaining different nutrients, if 2 or 3 nutrients can be incorporated into a single crop, it would offer enormous benefits to human beings and may even help to overcome several nutrient deficiency disorders latent in our country.

Question. Name the improved characteristics of wheat that helped India to achieve green revolution.
Answer : Improved characteristics of wheat that helped India to achieve green revolution are (i) Semi-dwarf nature (ii) Quick yielding feature (iii) High yielding feature (iv) Disease resistance

Question. Suggest some of the features of plants that will prevent insect and pest infestation.
Answer : Features of plants that will prevent insect and pest infestation are (i) Increasing hair growth on aerial parts of plants. (ii) Rendering the flowers nectarless. (iii) Enabling plants to secrete insect killing chemicals (toxins).

Question. What is the difference between a breed and a species? Give an example for each category.
Answer : A breed is a specific group of animals or plants having homogenous appearance, behaviour and other characteristics that distinguish it from other animals or plants of the same species, e.g., Afghan shepherd, American bulldog are breeds of dog. Species is one of the basic units of biological classification and a taxonomic rank. It can be defined as the largest group of organisms capable of interbreeding and producing fertile offspring. e.g., lion, cow, dog are species.

Question. Plants raised through tissue cultures are clones of the ‘parent’ plant. Discuss the utility of these plants.
Answer : Plants raised through tissue culture are very useful because they are identical copy of the parent plant. This is of great use when desirable traits of the parent plant have to be maintained.

Question. Discuss the importance of testing of new plant varieties in a geographically vast country like India.
Answer : Before the new plants are generated through plant breeding programs, they need to be evaluated for their yield and other agronomic traits of quality, disease resistance, etc. The testing is done on the farmers’ field for at least three growing seasons, at different locations in the country representing all the agroclimatic zones, where the crop is usually grown. The material is evaluated in comparison to the best available local crop cultivar known as a check or reference cultivar.

Long Answer Type Questions

Question. (a) Mutations are beneficial for plant breeding. Taking an example, justify the statement.
(b) Discuss briefly the technology that made us self-sufficient in food production.
Answer : (a) It is possible to induce mutations artificially in plants through use of chemicals or radiations (like gamma radiations), and then selecting and using those plants that have the desirable character as a source in breeding. This process is called mutation breeding. In mung bean, resistance to yellow mosaic virus and powdery mildew was induced by mutations. (b) Traditional farming can only yield a limited biomass, as food for humans and animals. Better management practices and increase in agricultural land area can increase yield, but only to a limited extent. Plant breeding as a technology has helped increase production to avery large extent. Plant breeding is the purposeful manipulation of plant species in order to create desired plant types that are better suited for cultivation, give better yields and are disease resistant. This technology has given support to green revolution, which was responsible for not merely meeting the national requirements in food production, but also helped us to export it.

Question. Discuss how the property of plant cell totipotency has been utilised for plant propagation and improvement. K Thinking Process The property of plant cells that helped them to grow into a new plant is totipotency. The production of healthy plantlet by rapid vegetative multiplication is done under aseptic and controlled conditions.
Answer : Plant cell totipotency can be utilised for plant propagation and improvement
(i) By application of these methods it is possible to achieve propagation of a large number of plants in very short time. Plants like tomato, banana, apple, etc., have been produced on commercial scale.
(ii) Healthy plants can be recovered from diseased plants (by micropropagation). This is done by removing the meristem, which is disease—free and growing it in vitro. This has been done in banana, sugarcane potato, etc.

Question. You are a Botanist working in the area of plant breeding. Describe the various steps that you will undertake to release a new variety.
Answer : Plant breeding programmes are carried out in a systematic way world wide-in government institutions and commercial companies.
The main steps in breeding a new genetic variety of a crop are
(i) Collection of Variability Genetic variability is the root of any breeding programme. In many crops pre-existing genetic variability is available from wild relatives of the crop. Collection and preservation of all the different wild varieties, species and relatives of the cultivated species (followed by their evaluation for their characteristics) is a pre-requisite for effective exploitation of natural genes available in the populations. The entire collection (of plants/seeds) having all the diverse alleles for all genes in a given crop is called germplasm collection.
(ii) 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. Purelines are created wherever desirable and possible.
(iii) Cross Hybridisation Among the Selected Parents The desired characters have very often to be combined from two different plants (parents), e.g., high protein quality of one parent may need to be combined with disease resistance from another parent. This is possible by cross hybridising the two parents to produce hybrids that genetically combine the desired characters in one plant. This is a very time-consuming and tedious process since the pollen grains from the desirable plant chosen as male parent have to be collected and placed on the stigma of the flowers selected as female parent. Also, it is not necessary that the hybrids do combine the desirable characters, usually only one in few hundred to a thousand crosses shows the desirable combination.
(iv) Selection and Testing of Superior Recombinants This step consists of selecting, among the progeny of the hybrids, those plants that have the desired character combination. The selection process is crucial to the success of the breeding objective and requires careful scientific evaluation of the progeny. This step yields plants that are superior to both of the parents (very often more than one superior progeny plant may become available). These are self-pollinated for several generations till they reach a state of uniformity (homozygosity), so that the characters will not segregate in the progeny.
(v) Testing, Release and Commercialisation of New Cultivars The newly selected lines are evaluated for their yield and other agronomic traits of quality, disease resistance, etc. This evaluation is done by growing these in the research fields and recording their performance under ideal fertiliser application, irrigation and other crop management practices. The evaluation in research fields is followed by testing the materials in farmers’ fields, for at least three growing seasons at several locations in the country, representing all the agroclimatic zones when the crop is usually grown. The material is evaluated in comparison to the best available local crop. After evaluation the variety can be relased for the farmers.

Question. (a) The shift from grain to meat diets creates more demands for cereals. Why?
(b) A 250 kg cow produces 200 g of protein per day but 250 g of Methylophillus methylotrophus can produce 25 tonnes of protein. Name this emerging area of research. Explain its benefits.
Answer : (a) The shift from grain to meat diets creates more demand for cereals as it takes 3-10 kg of grain to produce 1 kg of meat by animal farming. (b) This research is related to single cell protein. Microbes are being grown on an industrial scale as a source of good protein. Microbes like Spirulina can be grown easily on materials like wastewater from potato processing plants (containing starch), straw, molasses, animal manure and even sewage, to produce large quantities and can serve as food rich in protein, minerals, fats, carbohydrate and vitamins. Such utilisation also reduces the environmental pollution.

Please click the link below to download pdf file for CBSE Class 12 Biology - Strategies for enhancement in food production strategies for enhancement in food production.