NCERT Exemplar Class 12 Biology Chapter 9 Strategies for Enhancement in Food Production

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TextbookNCERT
ClassClass 12
SubjectBiology
ChapterChapter 9
Chapter NameStrategies for Enhancement in Food Production
CategoryNCERT Exemplar

NCERT Exemplar Class 12 Biology Chapter 9 Strategies for Enhancement in Food Production

Multiple Choice Questions
Single Correct Answer Type

1. The chances of contacting bird flu from a properly cooked (above 100°C) chicken and egg are
(a) Very high (b) High
(c) Moderate (d) None
Answer. (d) Properly cooked (above 100°C) chicken and egg have no chances of contacting bird flu.

2. A group of animals which are related by descent and share many similarities are referred to as
(a) Breed (b) Race
(c) Variety (d) Species
Answer. (a) A group of animals which are related by descent and share many similarities are referred to as breed.

3. Inbreeding is carried out in animal husbandry because it
(a) Increases vigour (b) Improves the breed
(c) Increases heterozygosity (d) Increases homozygosity
Answer. (d) Inbreeding is carried out in animal husbandry because it increases homozygosity.

4. Sonalika and Kalyan Sona are varieties of
(a) Wheat (b) Rice
(c) Millet (d) Tobacco
Answer. (a) Sonalika and Kalyan Sona are varieties of wheat.

5. Which one of the following is not a fungal disease?
(a) Rust of wheat (b) SmutofBajra
(c) Black rot of crucifers (d) Red rot of sugarcane
Answer. (c) Black rot of crucifers is a bacterial disease.

6. In virus-infected plants the meristematic tissues in both apical and axillary buds are free of virus because
(a) The dividing cells are virus resistant
(b) Meristems have antiviral compounds
(c) The cell division of meristems are faster than the rate of viral multiplication
(d) Viruses cannot multiply within meristem cell(s).
Answer. (c) In virus-infected plants the meristematic tissues in both apical and axillary buds are free of virus because the cell division of meristems are faster than the rate of viral multiplication.

7. Several South Indian states raise 2-3 crops of rice annually. The agronomic feature that makes this possible is because of
(a) Shorter rice plant (b) Better irrigation facilities
(c) Early yielding rice variety (d) Disease resistant rice variety
Answer. (c) Several South Indian states raise 2-3 crops of rice annually. The agronomic feature that makes this possible is because of early yielding rice variety.

8. Which one of the following combination would a sugarcane farmer look for in the sugarcane crop?
(a) Thick stem, long intemodes, high sugar content and disease resistant
(b) Thick stem, high sugar content and profuse flowering
(c) Thick stem, short internodes, high sugar content, disease resistant
(d) Thick stem, low sugar content, disease resistant.
Answer. (a) Thick stem, long internodes, high sugar content and disease resistant, combination would a sugarcane farmer look for in the sugarcane crop.

9. Fungicides and antibiotics are chemicals that
(a) Enhance yield and disease resistance
(b) Kill pathogenic fungi and bacteria, respectively
(c) Kill all pathogenic microbes
(d) Kill pathogenic bacteria and fungi respectively.
Answer. (b) Fungicides and antibiotics are chemicals that kill pathogenic fungi and bacteria, respectively.

10. Use of certain chemicals and radiation to change the base sequences of genes of crop plants is termed
(a) Recombinant DNA technology (b) Transgenic mechanism (c) Mutation breeding (d) Gene therapy
Answer. (c) Use of certain chemicals and radiation to change the base sequences of genes of crop plants is termed as mutation breeding. Mutations is induced artificially through use of chemicals or radiations like gamma radiations. In mung bean, resistance to yellow mosaic virus and powdery mildew were induced by mutations.

11. The scientific process by which crop plants are enriched with certain desirable nutrients is called
(a) Crop protection (b) Breeding
(c) Bio-fortification (d) Bio-remediation
Answer. (c) Bio-fortification: It is the most practical means to improve public health. In bio-fortification breeding of crops with higher levels of vitamins and minerals or higher protein and healthier fats. In 2000, maize hybrids were developed that had twice the amount of amino acid lysine and tryptophan (MALT). Atlas 66 (Wheat variety), having high protein content has been used as a donor for improving cultivated wheat. Iron fortified rice variety contains over 5 times much Fe.

12. The term‘totipotency’refers to the capacity of a
(a) Cell to generate whole plant (b) Bud to generate whole plant
(c) Seed to germinate (d) Cell to enlarge in size
Answer. (a) The capacity of explant or any cell to generate whole plant is called cellular totipotency. Cellular totipotency is shown by all plant cells. Cellulartotipotency is as demonstrated by F.C. Steward.

13. Given below are a few statements regarding somatic hybridization. Choose the correct statements.
(i) Protoplasts of different cells of the same plant are fused.
(ii) Protoplasts from cells of different species can be fused.
(iii) Treatment of cells with cellulase and pectinase is mandatory.
(iv) The hybrid protoplast contains characters of only one parental protoplast,
(a) (i) and (iii) (b) (i) and (ii)
(c) (i) and (iv) (d) (ii) and (iii)
Answer. (d) Isolated protoplast (surrounded by plasma membranes) from two different varieties can be fused to get hybrid protoplasts which grow to form new plant. The enzyme required to obtain wall free or naked protoplasts are cellulase, hemiceilulase and pectinase, which dissolves cell wall. Somatic cell hybrid (protoplast hybrid) are produced with the help of polyethylene glycol (PEG) and sodium nitrate which promote fusion. In protoplast fusion, chemofusion and electrofusion are employed.

14. An explant is
(a) Dead plant
(b) Part of the plant
(c) Part of the plant used in tissue culture
(d) Part of the plant that expresses a specific gene.
Answer. (c) An explant is a part of the plant used in tissue culture.

15. The biggest constraint of plant breeding is
(a) Availability of desirable gene in the crop and its wild relatives
(b) Infrastructure
(c) Trained manpower
(d) Transfer of genes from unrelated sources
Answer. (a) The biggest constraint of plant breeding is availability of desirable gene in the crop and its wild relatives.

16. Lysine and tryptophan are
(a) Proteins (b) Non-essential amino acids
(c) Essential amino acids (d) Aromatic amino acids
Answer. (c) Lysine and tryptophan are essential amino acids.

17. Micro-propagation is
(a) Propagation of microbes in vitro
(b) Propagation of plants in vitro
(c) Propagation of cells in vitro
(d) Growing plants on smaller scale
Answer. (b) This method of producing thousands of plants through tissue culture is called micro-propagation. Banana, Apple and Tomato are produced on commercial scale using this method.

18. Protoplast is
(a) Another name for protoplasm
(b) An animal cell 
(c) A plant cell without a cell wall
(d) A plant cell
Answer. (c) Protoplast is a plant cell.without a cell wall.

19. To isolate protoplast, one needs
(a) Pectinase (b) Cellulase
(c) Both pectinase and cellulase (d) Chitinase
Answer. (c) The enzyme required to obtain wall free or naked protoplasts are cellulase, hemiceliulase and pectinase, which dissolves cell wall.

20. Which one of the following is a marine fish?
(a) Rohu (b) Hilsa
(c) Catla (d) Common Carp
Answer. (b) Freshwater edible fished: Rohu, Catla and Common carp. Marine edible fishes: Sardines, Hilsa, Mackerel and Pomfrets.

21. Which one of the following products of apiculture is used in cosmetics and polishes?
(a) Honey (b) Oil
(c) Wax (d) Royal jelly
Answer. (c) Wax is a product of apiculture used in cosmetics and polishes.

22. More than 70 per cent of livestock population is in
(a) Denmark . (b) India
(c) China (d) India and China
Answer. (d) More than 70% of the world livestock population is in India and China, but contribution to the world farm produce is only 25% (means productivity per unit is very low).

23. The agriculture sector of India employs about
(a) 50 per cent of the population (b) 70 per cent of the population
(c) 30 per cent of the population (d) 60 per cent of the population
Answer. (d) The agriculture sector of India employs about 60 per cent of the population.

24. 33 percent of India’s (Gross Domestic Product) comes from
(a) Industry (b) Agriculture
(c) Export (d) Small-scale cottage industries.
Answer. (b) 33 percent of India’s (Gross Domestic Product) corner from agriculture.

25. A collection of all the alleles of all the genes of a crop plant is called
(a) Germplasm collection (b) Protoplasm collection
(c) Herbarium (d) Somaclonal collection
Answer. (a) A collection of all the alleles of all the genes of a crop plant is called germplasm collection.

Very Short Answer Type Questions 
1. Millions of chicken were killed in West Bengal, Assam, Orissa and Maharashtra recently, What was the reason?
Answer. Millions of chicken were killed (culled) in West Bengal, Orissa and Maharashtra because they were found to be infected with H5N1 virus, the causal organism of Bird Flu.

2. Can gamma rays used for crop improvement programmes prove to be harmful for health? Discuss.
Answer. Gamma rays used for crop improvement programmes cannot be harmful for health if they are not exposed directly to the human beings. It only induces mutation in the crop varieties.

3. In animal husbandry, if two closely related animals are mated for a few generations, it results in loss of fertility and vigour. Why is this so?
Answer. The phenomenon being referred to is called ‘Inbreeding Depression’ and results in loss of fertility and vigour. This happens because the recessive alleles tend to get together and express harmful effects in the progeny.

4. In the area of plant breeding, it is important not only to preserve the seeds of the variety being cultivated, but also to preserve all its wild relatives. Explain with a suitable example.
Answer. In the area of plant breeding, it is important not only to preserve the seeds of the variety being cultivated, but also to preserve all its wild relatives because several wild relatives of different cultivated species of plants seem to have certain resistant characters but their yields are very low. Hence, there is a need to introduce the resistant genes into the high-yielding cultivated varieties.

5. Name a man-made cereal. Trace how it was developed and where it is used?
Answer. Triticale. It was developed by crossing Triticum aestivum (wheat) and Secale cerale (rye).

ncert-exemplar-problems-class-12-biology-strategies-enhancement-food-production-1

6. Fill in the blanks:

Answer. I. Cellulase; II. Somatic hybridization; III. Pomato; IV. Somatic hybrid

7. 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.
a. Mating of closely related individuals within the same breed
b. Mating of animals of same breed but having no common ancestors on either side for 4-6 generations
c. Mating of animals of two different species
d. Breeding of animals belonging to different breeds
(i) Cross breeding, (ii) Inter-specific hybridization,
(iii) Out breeding, (iv) Out crossing, (v) Inbreeding
Answer. a. Mating of closely related individuals within the same breed—Inbreeding
b. Mating of animals of same breed but having no common ancestors on either side for 4-6 generations—Out crossing
c. Mating of animals of two different species—Inter-specific hybridization
d. Breeding of animals belonging to different breeds—Cross breeding

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

9. Why are plants obtained by protoplast culture called somatic hybrids?
Answer. Plants obtained by protoplast culture are called somatic hybrids because these are obtained by fusion of somatic cells of two different plants.

10. What is protoplast fusion?
Answer. The ability of protoplasts obtained from two different cells to fuse and form a hybrid protoplast is called protoplast fusion.

11. Why is it easier to culture meristems Compared to permanent tissues?
Answer. Meristems have the capacity of division while permanent tissue have lost the capacity of division.

12. Why are proteins synthesised from SpiruJina called single cell proteins?
Answer. Proteins synthesised from Spirulina are called single cell proteins (SCP) because it is a single celled organism that produce large quantities of food rich in protein, minerals, fats, carbohydrate and vitamins.

13. A person who is allergic to pulses was advised to take a capsule of Spirulina daily. Give the reasons for the advise.
Answer. Humans derive protein from pulses. If a person is allergic to pulses was advised to take a capsule of Spirulina daily because Spirulina is rich in protein.

14. What is aquaculture? Give example of an animal that can be multiplied by aquaculture.
Answer. The rearing of aquatic animals or the cultivation of aquatic plants for food is called aquaculture. Fishes, shell-fish and crustaceans (prawns, crabs, etc.) are the animals that can be multiplied by aquaculture.

15. What are the duties of a veterinary doctor in management of a poultry farm?
Answer. Duties of a veterinary doctor:
1. Veterinary doctor treat disease or injury in animals, which includes diagnosis and treatment.
2. Veterinary doctor is concerned with prophylactic treatment, in order to prevent problems occurring in the future.
3. Veterinary doctor uses vaccination against common animal diseases, such as rabies.
4. Veterinary doctor has important roles in public health and the prevention of zoonoses.

16. Would it be wrong to call plants obtained through micropropagation as ‘clones’? Comment.
Answer. No, it is not wrong because each of the plant will be genetically identical to the original plant from which they were grown, i.e., they are clones/somaclones.

17. How is a somatic hybrid different from a hybrid?
Answer. Isolated’protoplasts from two different varieties of plants can be fused to get hybrid protoplasts, which can be further grown to form a new hybrid plant that is called somatic hybrid. –

18. What is emasculation? Why and when is it done?
Answer. Removal of anther from a bisexual flower is called emasculation. It is used to avoid self-pollination and is used in artificial hybridisation programme. It is done before the dehiscence of anther.

19. Discuss the two main limitations of plant hybridization programme.
Answer. (i) Plant hybridization programme is often constrained by the availability of limited number of disease resistance genes that are present in various crop varieties or wild relatives.
(ii) Several wild relatives of different cultivated species of plants have been shown to have certain resistant character but have very low yield.

20. Interspecific crosses are rare in nature and intergeneric crosses almost unknown. Why?
Answer. The crosses between two different species are called interspecific crosses. As two species are reproductively isolated, the interspecific hybrid is sterile (like mule). Intergenic hybrids are almost non-viable hence intergenic hybrids are almost unknown.

21. Differentiate between pisciculture and aquaculture.
Answer. Pisciculture or fishery is an industry devoted to the catching, processing or selling of fish, shellfish or other aquatic animals.
The rearing of aquatic animals or the cultivation of aquatic plants for food is called aquaculture. .

22. Give two important contributions of Dr. M. S. Swaminathan.
Answer. (i) M.S. Swaminathan developed short-duration high-yielding varieties of rice including scented Basmati.
(ii) He is also known for the development of the concept of crop cafeteria, crop scheduling and genetically improving the yield and quality.

23. The term ‘desirable trait’ can mean different things for different plants.. Justify the statement with suitable examples.
Answer. In millets, resistance to water stress is desirable trait while in mung bean, resistance to yellow mosaic*virus and powdery mildew are desirable traits.

Short Answer Type Questions
1. You are planning to set up a Dairy Farm. Describe the various aspects you would consider before you start the venture.
Answer. Dairying is the management of animals for milk and its products for human consumption.
1. In dairy farm management, we deal with the processes and systems that increase yield and improve quality of milk. Milk yield is primarily dependent on the quality of breeds in the farm.
2. Selection of good breeds having high yielding potential (under the climatic conditions of the area), combined with resistance to diseases is very important.
3. For the yield potential to be realised the cattle have to be well looked after they have to be housed well, should have adequate water and be maintained disease free.
4. The feeding of cattle should be carried out in a scientific manner – with special emphasis on the quality and quantity of fodder.
5. Besides, stringent cleanliness and hygiene (both of the cattle and the handlers) are of paramount importance while milking, storage and transport of the milk and its products.

2. It is said, that diseases are spreading faster due to globalisation and increased movement of people. Justify the statement taking the example of H5N1 virus.
Answer. Diseases are spreading faster due to globalisation and increased movement of people because it is responsible for rapid spreading of infectious diseases.

3. Explain the concept of the Blue Revolution.
Answer. Rapid increase in the fishery industry in recent years is called blue revolution. For example, through aquaculture and pisciculture we have been able to increase the production of aquatic plants and animals, both fresh-water and marine. This has led to the development and flourishing of the fishery industry, and it has brought a lot of income to the farmers in particular and the country in general. We now talk about the ‘Blue Revolution’ which is being implemented along the same lines as ‘Green Revolution’.

4. A farmer was facing the problem of low yield from his farm. He was advised to keep a beehive in the vicinity. Why? How would the beehive help in enhancing yield? .
Answer. Bees are the pollinators of many of our crop species such as sunflower, Brassica, apple and pear. Keeping beehives in crop fields during flowering period increases pollination efficiency and improves the yield beneficial both from the point of view of crop yield and honey yield.

5. Life style diseases are increasing alarmingly in India. We are also dealing with large scale malnutrition in the population. Is there any method by which we can address both of these problems together?
Answer. Lifestyle disorders can be prevented by improving the lifestyle of a person. Taking too much of a stress can lead to heart stroke and paralysis which can be avoided by living in a healthy environment.
Malnutrition is very common in poor people who do not have access to nutritious food and India has a large scale population who are malnutritious. Proper distribution of food and less wasting can help to address both of these problems together.

6. How can we improve the success rate of fertilisation during artificial insemination in animal husbandry programmes?
Answer. The technology is called MOET or Multiple Ovulation Embryo Transfer. During the 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 mother cows. The method has been successfully used for cattle, sheep, buffalo etc.

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

8. Name the improved characteristics of wheat that helped India to achieve green revolution.
Answer. i. Semi-dwarf nature ii. Quick yielding feature iii. High yielding feature iv. Disease resistant feature

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

10. It is easier to culture plant cells in vitro as compared to animal cells. Why?
Answer. Plant have meristematic cells that have the capacity of division, so can grow easily in in vitro culture. Animals have mainly differentiated cells that have lost the capacity of division.

11. The culture medium (nutrient medium) can be referred to as a ‘highly enriched laboratory soil’. Justify the statement.
Answer. The culture medium (nutrient medium) can be referred to as a ‘highly enriched laboratory soil’ because in culture medium we must provide a carhon source such as sucrose and also inorganic salts, vitamins, amino acids and growth regulators like auxins, cytpkinins etc. .

12. Is there any relationship between dedifferentiation and the higher degree of success achieved in plant tissue culture experiments?
Answer. Yes, the cells that has lost the capability of division can regain the capacity of division through dedifferentiation. So, in plant tissue culture experiments more success is achieved.

13. “Give me a living cell of any plant and I will give you a thousand plants of the same type”. Is this only a slogan or is it scientifically possible? Write your comments and justify them. 
Answer. It is scientifically possible. By application of tissue culture it is possible to achieve propagation of a large number of plants in very short durations. This method of producing thousands of plants through tissue culture is called micro propagation. Each of these plants will be genetically identical to the original plant from which they were grown, i.e., they are somaclones.

14. What is the difference between n breed and a species? Give an example for each category.
Answer. A group of animals related by descent and similar in most characters like general appearance, features, size, configuration, etc., are said to belong to a breed. Hisardale is a new breed of sheep.
A group of individual that is reproductively isolated from other such group is called species. For examples, Panthera leo (lion) and Mangifera indica are different species.

15. Plants raised through tissue cultures are clones of the ‘parent’ plant. Discuss the utility of these plants.
Answer. Plant raised through tissue cultures are clones of the parent plant that means they are genetically identical to the original plant. They are utilised for maintaining a desirable trait of parent.

16. Discuss the importance of testing of new plant varieties in a geographically vast country like India.
Answer. 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 fertilizer application, irrigation, and other crop management practices. The evaluation in research fields is followed by testing the materials.in fanners’ fields, for at least three growing seasons at several 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-a check or reference cultivar.

17. Define the term ‘stress’ for plants. Discuss briefly the two types of stress encountered by plants.
Answer. Any unfavourable condition for the plant growth and development is called stress. For example, drought, salinity, cold, pest and diseases are different type of stresses.

18. Discuss natural selection and artificial selection. What are the implications of the latter on the process of evolution?
Answer. Artificial selection is the intentional breeding of plants or animals. Selective breeding is a technique used when breeding domesticated animals, such as dogs, pigeons or cattle.
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in heritable traits of a population over time.

19. Discuss briefly how pure lines are created in animal husbandry.
Answer. Inbreeding is necessary if we want to evolve a pure line in any animal. Inbreeding refers to the mating of more closely related individuals within the same breed for 4-6 generations.

20. 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 such experiments. This can be overcomed 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 dell membrane.

21. 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, and 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 offers enormous benefits to human beings and may even help overcome several nutrient deficiency disorders latent in our country.

Long Answer Type Questions
1. 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. 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. Pure lines 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), for example 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 (In chapter 2 details on how to make crosses have been described). 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 fertilizer 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 agro climatic zones where the crop is usually grown. The material is evaluated in comparison to the best available local crop cultivar a check or reference cultivar.

2. (a) The shift from grain to meat diets creates more demands for cereals. Why? (b) A250 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) It takes 3-10 kg of grain to produce 1 kg of meat using animal farming. That is why cereals demand increases.
(b) Production of single cell proteins (SCP) by microbes. Microbes are being grown on an Industrial scale. Spirulina can be easily grown on starch, molasses etc., and can make food which is rich in proteins, minerals, fats, carbohydrates and vitamins. This could be a good alternative for dealing with the problem of malnutrition.

3. What are the advantages of tissue culture methods over conventional method of plant breeding in crop improvement programmes?
Answer. The advantages of tissue culture methods are:
By application of these methods it is possible to achieve propagation of a large number ofplants in very short durations. This method of producing thousands of plants through tissue culture is called micro-propagation. Each of these plants will be genetically identical to the original plant from which they were grown, i.e., they are somaclones. Many important food plants like tonjato, banana, apple, etc., have been produced on commercial scale using this method. Try to visit a tissue culture laboratory with your teacher to better understand and . appreciate the process. Another important application of the method is the recovery of healthy plants from diseased plants. Although the plant is infected with a virus, the meristem (apical and axillary) is free of virus. Hence, one can remove the meristem and grow it in vitro to obtain virus-free plants. Scientists have succeeded in culturing meristems of banana, sugarcane, potato, etc.

4. ‘Modem methods of breeding animals and plants can alleviate the global food shortage’. Comment on the statement and give suitable examples.-
Answer. 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. Pure lines 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), for example 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 (In chapter 2 details on how to make crosses have been described). 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 fertilizer 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 agro climatic zones where the crop is usually grown. The material is evaluated in comparison to the best available local crop cultivar a check or reference cultivar.
(a) It takes 3-10 kg of grain to produce 1 kg of meat using animal farming. That is why cereals demand increases.
(b) Production of single cell proteins (SCP) by microbes. Microbes are being grown on an Industrial scale. Spirulina can be easily grown on starch, molasses etc., and can make food which is rich in proteins, minerals, fats, carbohydrates and vitamins. This could be a good alternative for dealing with the problem of malnutrition.
The advantages of tissue culture methods are:
By application of these methods it is possible to achieve propagation of a large number ofplants in very short durations. This method of producing thousands of plants through tissue culture is called micro-propagation. Each of these plants will be genetically identical to the original plant from which they were grown, i.e., they are somaclones. Many important food plants like tonjato, banana, apple, etc., have been produced on commercial scale using this method. Try to visit a tissue culture laboratory with your teacher to better understand and . appreciate the process. Another important application of the method is the recovery of healthy plants from diseased plants. Although the plant is infected with a virus, the meristem (apical and axillary) is free of virus. Hence, one can remove the meristem and grow it in vitro to obtain virus-free plants. Scientists have succeeded in culturing meristems of banana, sugarcane, potato, etc.

5. Does apiculture offer multiple advantages to farmers? List its advantages if it is located near a place of commercial flower Cultivation.
Answer. Bee-keeping or apiculture is the maintenance of hives of honeybees for the production of honey, ft has been an age-old cottage industry. Honey is a food of high nutritive value and also find its use in the indigenous systems of medicine. Honeybee also produces beeswax, which finds many uses in industry, such as in the preparation of cosmetics and polishes of various kinds. The increased demand of honey has led to large-scale beekeeping practices; it has become an established income generating industry, whether practiced on a small or on a large scale.
Bees are the pollinators of many of our crop species such as sunflower, Brass tea, apple and pear. Keeping beehives in crop fields during flowering period increases pollination efficiency and improves the yield-beneficial both from the point of view of crop yield and honey yield.

6. (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) Mutation is the process by which genetic variations are created through changes, in the base sequence within genes resulting in the creation of a new character or trait not found in the parental type. It is possible to induce mutations artificially through use of chemicals or radiations (like gamma radiations), and selecting and using the 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 were induced by mutations.
(b) 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. With advancements in genetics, molecular biology and tissue culture, plant breeding is now increasingly being carried out by using molecular genetic tools.

7. Discuss how the property of plant cell totipotency has been utilised for plant propagation and improvement
Answer. The capacity to generate a whole plant from any cell/explant is called totipotency. By application of these methods it is possible to achieve propagation of a large number of plants in very short durations. This method of producing thousands of plants through tissue culture is called micro propagation. Each of these plants will be genetically identical to the original plant from which they were grown, i.e., they are somaclones. Many important food plants like tomato, banana, apple, etc., have been produced on a commercial scale using this method. Try to visit a tissue culture laboratory with your teacher to better understand and appreciate the process.
Another important application ef the method is the recovery of healthy plants from diseased plants. Although the plant is infected with a virus, the meristem (apical and axillary) is free of virus. Hence, one can remove the meristem and grow it in vitro to obtain virus-free plants. Scientists have succeeded in culturing meristems of banana, sugarcane, potato, etc.

8. What are three options to increase food production? Discuss each giving the salient features, merits and demerits.
Answer. With ever increasing population of the world, enhancement of food production is a major necessity. Biological principles as applied to animal husbandry (See Ans 1 of short answer type questions) and plant breeding (See Ans 1) have a major role in our efforts to increase food production. Several new techniques like embryo transfer technology and tissue culture tecbniques(See Ans 7) are going to play a pivotal role in further enhancing food production.

All Chapter NCERT Exemplar Problems Solutions For Class12 Biology

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All Subject NCERT Exemplar Problems Solutions For Class12

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