CBSE Class 12 Biology Strategies For Enhancement In Food Production Worksheet Set B

 

Question. Mention the economic value of Apis indica.
Answer. Apis indica is common species of honey bee used in apiculture.

Question. Write the importance of MOET. 
Answer. Multiple Ovulation Embryo Transfer Technology (MOET) is the programme used to increase the herd size in a short time.

Question. List any two economically important products for humans obtained from Apis indica.
Answer. Honey and beewax are two economically important products obtained from Apis indica.

Question. Differentiate between outbreeding and outcrossing. 
Answer. Out breeding is breeding of unrelated animals which may be between individuals of same breed or between different breeds or different species. Outcrossing is the practice of mating of animals within the same breed but having no common ancestors. This is the best breeding method for animals that are below average in milk production, growth rate in beef cattle, etc. A single outcross often helps to overcome inbreeding depression.

Question. State the disadvantage of inbreeding among cattle. How it can be overcome? 
Answer. Continuous inbreeding among cattle leads to reduced fertility and productivity, a phenomenon called inbreeding depression. It can be overcome by mating selected unrelated superior animals of same breed. This helps to restore fertility and yield.

Question. Explain giving reasons, the need to keep the bee-hives in the fields during flowering season.
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 crop yield. Also bees collect nectar from flowers of these crop plants to make honey hence, honey yield also increases.

Question. How is a pureline in an animal raised ? Explain.
Answer. A pure line in an animal is raised through inbreeding. In this method, superior males and females of the same breed are selected and mated. The progeny obtained from such matings are evaluated and superior males and females among them are identified for further mating. Inbreeding increases homozygosity. It exposes harmful recessive genes that are eliminated by selection.

Question. MOET programme has helped in increasing the herd size of the desired variety of cattle. List the steps involved in conducting the programme.
Answer. Multiple Ovulation Embryo Transfer or MOET is a method to improve the herd size of desired variety of cattle. The steps involved in MOET are as follows:-
(i) Hormones (with FSH-like activity) are given to cow for inducing follicular maturation and super ovulation i.e., production of 6-8 ova in one cycle.
(ii) Cow is either mated with best bull or artificially inseminated.
(iii) The embryos with 8-32 cell stages are recovered and transferred to surrogate mother and genetic mother becomes available for new cycle of super ovulation.

Question. Which one of the following is used in apiculture ?
Hilsa, Apis indica, Sonalika 
Answer. Apis indica is the most common species of bees used in apiculture. Hilsa is a marine fish. Sonalika is the high yielding and disease resistant variety of the wheat.

Question. List any four important components of Poultry Farm Management ? 
Answer. The four important components of poultry farm management are:-
(i) Selection of disease free and suitable breeds: Selection of breeds is the most important aspect. The breed should be disease free and suitable to the environmental conditions.
(ii) Brood house: Brood house should not be crowded and should be rain proof and protected from predators.
(iii) Sanitation and hygiene: The area should be cleaned and disinfected.
(iv) Feed management: Feeding constitutes the major management concern in egg and meat production.

Question. (a) List three advantages of inbreeding in cattle.
(b) Name an improved breed of cattle.
Answer. (a) Three advantages of inbreeding in cattle are:
(i) Inbreeding increases homozygosity. Hence, it is necessary if we want to evolve pureline.
(ii) Inbreeding exposes those recessive genes that are eliminated by selection.
(iii) It helps in accumulation of superior genes and elimination of less desirable genes.
(b) Jersey is an improved breed of cattle.

Question. Mention and describe any three methods to overcome inbreeding depression in animal husbandry. 
Answer. Continuous inbreeding usually reduces fertility and productivity. This is called inbreeding depression. Inbreeding depression can be overcome by outcrossing, crossbreeding and interspecific hybridisation. Outcrossing is the practice of mating of animals within the same breed, but having no common ancestors on either side for 4-6 generations.
A single outcross often helps to overcome inbreeding depression. In cross-breeding superior males of one breed are mated with superior females of another breed. Cross-breeding allows the desirable qualities of two different breeds to be combined. In interspecific hybridisation, male and female animals of two different related species are mated.

Question. (a) Mention the kind of areas that are suitable for bee-keeping practices.
(b) Mention any two uses of bee wax.
Answer. (a) Bee-keeping can be practiced in an area where there are sufficient bee pastures of some wild shrubs, fruit orchards and cultivated crops.
(bc) Beewax is used in cosmetics, creams, ointments, paints and polishes.

Question. What is ‘Blue revolution’? Name two freshwater and two marine edible fish.
Answer. Blue revolution is the movement implemented along the same lines as green revolution related to the production of fish and fish products on a large scale. Freshwater edible fishes are rohu and catla. Marine water edible fishes are hilsa and Bombay duck.

Question. List any three outbreeding practices carried out to breed domestic animals. Explain the importance of each one listed. 
Answer. The three outbreeding practices carried out to breed domestic animals are: outcrossing, cross- breeding and interspecific hybridisation. Outcrossing is the mating of animals within the same breed but not having common ancestors on either side of their pedigree up to 4-6 generations. Outcrossing is the best breeding method for animals that are below average in milk production, growth rate in beef and cattle etc. Sometimes only one outcross helps to overcome inbreeding depression.
In cross-breeding superior males of one breed are mated with superior females of another breed. crossbreeding allows the desirable qualities of two different breeds to be combined. The progeny hybrid animals may themselves be used for commercial production. Alternatively, they may be subjected to some form of inbreeding and selection to develop new stable breeds that may be superior to the existing breeds e.g., Hisardale is a new breed of sheep developed by crossing Bikaneri ewes and Marino rams. In interspecific hybridisation, male and female animals of two different species are mated. The progeny obtained from such a mating are usually different from both the parental species. But in some cases, the progeny may combine desirable characters of both the parents. Mule is produced from a cross between female horse (mare) and male donkey.

Question. How has mutation breeding helped in improving the production of mung bean crop?
Answer. In mutation breeding, mutations are induced artificially through the use of chemicals or radiations and plants having desired character are selected as a source in breeding. In mung bean, resistance to yellow mosaic virus and powdery mildew are introduced by mutation breeding.

Question. Name any two common Indian millet crops. State one characteristic of millets that has been improved as a result of hybrid breeding so as to produce high yielding millet crops.
Answer. Jowar and bajra are two Indian millet crops. High yielding hybrid varieties of millet crops are resistant to pest attack and water stress.

Question. Enumerate four objectives for improving the nutritional quality of different crops for the health benefits of the human population by the process of “Biofortification”.
Answer. Biofortification is the breeding of crops with higher levels of vitamins and minerals or higher proteins and healthier fats, to improve the public health by practical means. Plant breeding is undertaken for improved nutritional quality of the plants with the objectives of improving :
– Protein content and quality
– Oil content and quality
– Vitamin content
– Micronutrient and mineral content.

Question. Name the following:
(a) The semi – dwarf variety of wheat which is high yielding and disease resistant.
(b) Any one interspecific hybrid mammal.
Answer. (a) Sonalika and Kalyan Sona are semi-dwarf varieties of wheat, which are high yielding and disease resistant.
(b) Mule is an interspecific hybrid mammal, which is produced from a cross between female horse (mare) and male donkey.

Question. Identify A, B, C and D in the following table.

Crop	Variety	Resistance to Disease
A	Himgiri	Hill bunt
Brassica	Pusa Swarnim	B
Cauliflower	C	Black rot
D	Pusa Komal	Bacterial blight

Answer. In the given table : A – Wheat
B – White rust

Question. Explain the advantage of cross breeding of the two species of sugarcane in India.
Answer. Saccharum barberi was originally grown in North India, but had poor sugar content and yield. However, Saccharum officinarum had higher sugar content and thicker stems but did not grow well in North India. These two species were crossed to have sugarcane varieties combining the desirable qualities of high sugar, high yield, thick stems and ability to grow in the sugarcane belt of North India.

Question. Name and explain the mechanism by which seeds from hybrid plants are developed, that are able to retain the desired hybrid character in the progeny.
Answer. 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. The main steps in plant breeding are:-
(i) Collection of variability
(ii) Evaluation and selection of parents
(iii) Cross hybridisation among the selected parents (iv) Selection and testing of superior recombinants (v) Testing, release and commercialisation of new cultivars.

Question. Enumerate, in sequential order, the 4 steps that a plant breeder should know to obtain a diseaseresistant crop. 
Answer. The various sequential steps are : screening germplasm for resistance sources, hybridisation of selected parents, selection and evaluation of hybrids and testing and release of new varieties.

Question. List two steps that help in introducing the desired mutation into the crop.
Answer. The steps in mutation breeding are :
(i) Inducing mutation through various mutagens/methods.
(ii) Screening the plant materials for disease resistance.
(iii) Multiplication for these selected plants for direct use or for use in breeding.
(iv) Hybridisation of the selected plant materials.
(v) Selection for disease resistance, testing and release as a variety.

Question. What is ‘biofortification’ ? Write its importance. Mention the contribution of Indian Agricultural Research Institute towards it with the help of two examples.
Answer. Breeding of crops with higher levels of vitamins and minerals or higher proteins and healthier fats is called biofortification. This is the most practical aspect to improve the health of the people.
Plant breeding is undertaken for improved nutritional quality of the plants with the objectives of improving :
– Protein content and quality
– Oil content and quality
– Vitamin content
– Micronutrient and mineral content.
Indian Agricultural Research Institute (IARI), New Delhi, has also developed many vegetable crops that are rich in minerals and vitamins. For example, vitamin A enriched carrots, pumpkin, spinach; vitamin C enriched bitter gourd, bathua, tomato; iron enriched spinach and bathua and protein enriched beans.

Question. Mention the role of ‘genetic mother’ in MOET.
Answer. In MOET, genetic mother is the biological mother of the offspring. Hormones with FSH like activity are given to genetic mothers for inducing follicular maturation and superovulation. As a result, 6-8 eggs are produced instead of 1 egg per cycle. She is then mated with a superior bull or artificially inseminated. Embryos at 8-32 cell stage are recovered and transferred to surrogate mother and the genetic mother is again available for super ovulation.

Question. Write a professional approach at genetic level that can help the farmer to improve the milk yield of low milk producing cows on his farm.
Answer. Outcrossing is the best breeding method and professional approach that can help farmer improve the milk yield in animals that are below average in milk production.

Question. Write the name of the following :
(a) The most common species of bee suitable for apiculture.
(b) An improved breed of chicken. 
Answer. (a) Apis indica
(b) Leghorn is an improved breed of chicken.

Question. How can crop varieties be made disease resistant to overcome food crisis in India? Explain. Name one disease resistant variety in India of:
(a) Wheat to leaf and stripe rust
(b) Brassica to white rust 
Answer. Breeding for disease resistant crop varieties is carried out by conventional breeding techniques or by mutation breeding. The conventional method of breeding for disease resistance is hybridisation and selection. The various sequential steps are: screening germplasm for resistance sources, hybridisation of selected parents, selection and evaluation of hybrids and testing and release of new varieties. Conventional breeding is often constrained by the availability of limited number of disease resistance genes that are present and identified in various crop varieties. Inducing mutations in plants sometimes leads to desirable genes being identified. Plants having these desirable characters can either be multiplied directly or can be used in breeding.
(a) Variety of wheat resistant to leaf and stripe rust– Himgiri
(b) Variety of Brassica resistant to white rust – Pusa Swarnim

Question. With advancements in genetics, molecular biology and tissue culture, new traits have been incroporated into crop plants.
Explain the main steps in breeding a new genetic variety of a crop.
Answer. Plant breeding is the purposeful manipulation of plant by crossing different varieties in order to create desired plant types that are better suited for cultivation, give better yields and are disease resistant. Plant breeding involves the following steps :
(i) Collection of variability – Collection and preservation of all the different wild varieties, species and relatives of the cultivated species. The entire collection (of plant/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.
(iii) Cross hybridisation among the selected parents- Hybridisation is crossing of two or more types of plants for bringing their traits together in the progeny. The procedure of hybridisation involves selection of parents with desired characters, selfing, emasculation, bagging, tagging and artificial pollination.
(iv) Selection and testing of superior recombinants – This is the selection of the plants, from the progeny of hybrids, which have the desired combined character. The selected plants are then self pollinated for several generations to get a uniformity i.e. homozygosity. Selection is of two types: (a) Selection in self- pollinated crops – The degree of cross pollination is less than 5%. There is repeated self pollination of selected plants till superior homozygous genotypes are obtained. The best one is used as new variety. The self-pollinated progeny of homozygous plant constitutes a pure line.
(b) Selection in cross-pollinated crops – The cross- pollinated crops are heterozygous for most of their genes and their population contains plants of several different genotypes. Superior genotype plants are selected and are allowed to crossbreed (these plants are not allowed to self breed) so that heterozygosity is also maintained.
(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. These selected cultivars are then tested with local best cultivar and are then released for commercialisation.

Question. (a) What is plant breeding? List the two steps the classical plant breeding involves.
(b) How has the mutation breeding helped in improving crop varieties? Give one example where this technique has helped.
(c) How has the breeding programme helped in improving the public nutritional health?
State two examples in support of your answer.
Answer. (a) Plant breeding is an applied branch of botany which deals with the improvement of cultivated varieties (cultivars) of plants. It deals with the improvement in the heredity of crops and production of new crop varieties which are far better than original types in all respects. The main steps in production a new genetic variety of a crop are: evaluation and selection of parents and cross hybridisation among them. Testing, release and commercialisation of new cultivars are the other steps involved.
(b) 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.
Resistance to yellow mosaic virus and powdery mildew in mung bean were introduced by mutations.
(c) Breeding of crops with higher levels of vitamins and minerals or higher protein and healthier fats is called biofortification. This is the most practical aspect to improve the health of the people. Plant breeding is undertaken for improved nutritional quality of the plants with the objectives of improving :
– protein content and quality
– oil content and quality
– vitamin content
– micronutrient and mineral content.
Maize hybrids that had twice the amount of the amino acids–lysine and tryptophan, compared to existing maize hybrids were developed in 2000. Wheat variety with high protein content Atlas 66 has been used as a donor for improving cultivated wheat.

Question. How can healthy potato plants be obtained from a desired potato variety which is virus infected? Explain. 
Answer. Healthy potato plants can be obtained from the desired potato variety which is virus infected by meristem culture. Cultivation of axillary or apical shoot meristems is called meristem culture. The apical and axillary meristems of the infected plant is virus free because rate of division of meristematic cells is higher than the rate at which virus multiplies hence virus cannot invade newly formed meristematic cell. Meristem is removed and grown in vitro to obtain healthy virus-free potato plants.

Question. Name the technology used in micropropagation of plants. Write the genetic significance of the plants raised through this technique. Give two examples where this technology is commercially exploited.
Answer. The method of producing thousand of plants through tissue culture is called micropropagation. Each of these plants will be genetically identical to the original plant from which they are grown, i.e., they are somaclones. Many important food plants like tomato, banana, apple, etc., have been produced on commercial scale using this method.

Question.What is haploidy? How are haploid plants raised? How are they helpful in plant breeding?
Answer. Individuals or cells that contain one set of chromosomes as in gametes, are called haploids and this condition is called haploidy.
Haploid plants are of great significance as they are used in plant breeding for the production of homozygous plants. Formation of haploids is called haploid production. Haploid individuals arise from the gametes and are sterile hence of no direct value. The chromosome number of these haploids is doubled by using colchicine to obtain homozygous plants.

Question. Differentiate between somaclones and somatic hybrids. Give one example of each.
Answer. Differences between somaclones and somatic hybrids are as follows :

Somaclones	Somatic hybrids
Somaclones are plants that develop from any part of a plant by tissue culture or micropropagation.	Somatic hybrids are produced by fusion of somatic cells of two different varieties or species.
Somaclones are genetically identical to the parent plant from which they are grown.	Somatic hybrids are genetically dierent from parent plant.
New genes cannot be introduced during somaclone formation.	New genes can be introduced such as male sterility, herbicide resistance,etc., by genetic manipulation during formation of somatic hybrid plants.
It helps to evolve pure line.	Pure lines are not developed.
E.g. commercial production of ornamental plants like lily, orchid, eucalyptus and fruits trees like tomato, apple, banana.	E.g. pomato (somatic hybrid between potato and tomato). Somatic hybrids are also obtained between rice and carrot.

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