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

Question. The process of breeding by artificially inducing mutations with chemicals or radiations is called
(a) artificial breeding
(b) chemical breeding
(c) synthetic breeding
(d) mutation breeding
Answer : D

Question. The sugarcane growing in North India and having a poor sugar content and yield is
(a) Saccharum officinarum
(b) Saccharum barberi
(c) Both (a) and (b)
(d) None of the above
Answer : B

Question. During MOET at which of the following stages, embryo is transferred to surrogate mothers
(a) Unfertilised ovules
(b) 2-celled stage
(c) Fertilised egg
(d) 8-32 celled stage
Answer : D

Question. In which of the following techniques high milk giving breeds of females and high quality meat giving bulls have been bred successfully to increase herd size short time?
(a) MOET
(b) Artificial insemination
(c) Interspecific hybridisation
(d) Induced mutation
Answer : A

Question. Fill up the blanks.
I. ……..A……refers to the cross of superior males of one breed with superior females of another breed.
II. ….....B……is a method of controlled breeding in which semen from the selected male parent is injected into the reproductive tract of the selected female parent.
III. ……C……refers to crossing between male and female animals of two different species.
IV. ……D……is a programme for herd improvement in animals like cattle, sheep, buffaloes, etc.
Answer : B

Question. Rearing of honeybees for obtaining honey and beeswax is called
(a) pisciculture
(b) sericulture
(c) apiculture
(d) aquaculture
Answer : C

Question. Most common honeybee species in India
(a) Apis indica
(b) Apis florea
(c) Apis mellifera
(d) Apis dorsata
Answer : A

Question. Which of the following given point is important for successful bee-keeping?
(a) Knowledge of the nature and habits of bees
(b) Selection of suitable location for keeping the beehives
(c) Catching and hiving of swarms (group of bees) and their management during different seasons
(d) All of the above
Answer : D

Question. Outbreeding is an important strategy of animal husbandry because it 
(a) helps in accumulation of superior genes
(b) is useful in producing purelines of animals
(c) is useful in overcoming inbreeding depression
(d) exposes harmful recessive genes that are eliminated by selection
Answer : C

Question. When breeding is between the unrelated animals, including individuals of the same breed but having no common ancestors for 4-6 generations or between different breeds or different species, is called
(a) outbreeding
(b) inbreeding
(c) controlled breeding
(d) hybridisation
Answer : A

Question. Keeping beehives in crop field during flowering period
(a) improve honey and wax yield
(b) improves crop yield
(c) pollination efficiency
(d) All of the above
Answer : D

Question. A superior female, in the case of cattle is the …A…that produces more milk per lactation. On the other hand, a superior male is the …B…, which gives rise to …C… as compared to those of other males. Here, A to C refers to
(a) A–cow, B–bull, C–superior progeny
(b) A–buffalo, B–bull, C–inferior progeny
(c) A–cow, B–bull, C–inferior progeny
(d) A–cow, B–bull, C–normal progeny
Answer : A

Question. Continued inbreeding
(a) reduces fertility
(b) reduces productivity
(c) causes inbreeding depression
(d) All of the above
Answer : D

Question. Name the industry that includes catching, processing or selling of aquatic animals.
(a) Fisheries
(b) Apiculture
(c) Sericulture
(d) None of these
Answer : A

Question. Which of the following is not a freshwater fishes?
(a) catla
(b) rohu
(c) common carp
(d) mackerel
Answer : D

Question. Edible fishes found in marine water habitat is/are
(a) sardines
(b) pomfrets
(c) Hilsa
(d) All of the above
Answer : D

Question. The byproducts obtained from fisheries are
(a) isinglass, oil, shagreen and fishmeal
(b) eggs, meat, oil and leather
(c) isinglass and eggs
(d) None of the above
Answer : A

Question. ……… is the purposeful manipulation of plant species in order to create plant types that are better suited for cultivation, give better yield and are disease resistant. Fill up the blanks.
(a) Aquaculture
(b) Plant breeding
(c) Animal husbandry
(d) Apiculture
Answer : B

Question. Following are the steps to produce a new genetic variety of crop.
(c) A–Testing of parents; B–Selection of superior recombinants
(d) A–Evaluation and selection of parents; B–Selection and testing of superior recombinants
Answer : D

Question. Which of the following is considered as the root of any breeding programme?
(a) Genetic variability
(b) Cross hybridisation
(c) Hybrid vigour
(d) Heterosis
Answer : A

Question. In mutation breeding, mutations are induced by using radiation like
(a) Gamma rays
(b) X-rays
(c) UV-rays
(d) All of these
Answer : D

Question. In plant breeding programmes, the entire collection (of plants/seeds) having all the diverse alleles for all genes in a given crop is called
(a) selection of superior recombinants
(b) cross-hybridisation among the selected parents
(c) evaluation and selection of parents
(d) germplasm collection
Answer : D

Question. Which of the following is the main aim of evaluation of germplasm in plant breeding programme?
(a) To identify plants with desirable combination of characters
(b) For effective exploitation of the natural genes
(c) To look for harmful mutated gene
(d) For collection of variability
Answer : A

Question. In case of plant breeding, cross hybridisation is a time consuming and tedious process because
(a) pre-existing genetic variability is collected from wild varieties, species and relatives of the cultivated crop species
(b) it involves the selection of plants among the progeny of the hybrids with desired combination of characters
(c) it involves emasculation and bagging techniques to transfer desired pollen grains to the stigma of desired plant
(d) None of the above
Answer : C

Question. During selection and testing of superior recombinants, selected superior plants are self-pollinated for several generation. Why?
(a) So that they reach a state of uniformity (homozygosity)
(b) So that the characters will not segregate in the progeny
(c) Both (a) and (b)
(d) Selected superior plants are not self-pollinated but cross-pollinated
Answer : C

Question. Among the following edible fishes, which one is a marine fish having rich source of omega-3 fatty acids? 
(a) Mystus
(b) Magur
(c) Mrigala
(d) Mackerel
Answer : D

Question. Green revolution in India was possible due to
(a) exploitation of high yielding varieties
(b) intensive cultivation
(c) better irrigation, fertilisers and pesticide facilities
(d) All of the above
Answer : D

Question. Green revolution depended mainly on plant breeding techniques for high yielding and disease resistant varieties in
(a) wheat
(b) rice
(c) maize
(d) All of these
Answer : D

Question. Which of the following activities has contributed towards increased production of aquatic organisms?
(a) Pisciculture and sericulture
(b) Pisciculture and aquaculture
(c) Pisciculture and blue revolution
(d) Blue and green revolution
Answer : B

Question. What objectives are undertaken during crop-breeding for improved nutritional quality?
(a) Improve protein and oil content and quality
(b) Improve content of micronutrients and minerals
(c) Improved vitamin content
(d) All of the above
Answer : D

Very Short Answer Questions

Question. Which of the following is the semi-dwarf wheat that is high yielding and disease resistant? Pusa Shubra, Kalyan sona, Ratna
Answer. Kalyan sona

Question. Write the name of the following:
(a) The most common species of bees suitable for apiculture.
(b) An improved breed of chicken. 
Answer. (a) Apis indica/Apis mellifera/Apis dorsata
(b) Leghorn/Rhode island red/Minorca.

Question. Name any two diseases the ‘Himgiri’ variety of wheat is resistant to. 
Answer. Leaf and stripe rust; Hill bunt

Question. What is meant by the term ‘breed’? What are the objectives of animal breeding?
Answer. Breed refers to the group of animals having same ancestral characters, general appearance, size,etc.
Objectives of animal breeding:
(i) To increase the quantity of yield.
(ii) To improve the desirable qualities of the produce.

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

Short Answer Questions

Question. What is inbreeding depression? Why do the self-pollinated crops not show the ill effects of inbreeding depression?
Answer. The continuous inbreeding may lead to reduced fertility and productivity called inbreeding depression. Self-pollinated crop does not show the ill effects of inbreeding depression because the deleterious allele becomes homozygous and exhibits their lethal effect so it is eliminated by selection.

Question. Suggest four important steps to produce a disease resistant plant through conventional plant breeding technology. 
Answer. Steps for producing disease resistant plants are:
(i) Screening of germplasm (for resistance sources)
(ii) Hybridisation of selected parents
(iii) Selection and evaluation of hybrids (for disease resistance and high yields)
(iv) Testing and release of new varieties.

Question. Name the methods employed in animal breeding. According to you which of the methods is best? Why?
Answer. The methods employed in animal breeding are:
(i) Natural methods: These can be carried out by inbreeding and outbreeding methods.
(ii) Artificial methods: These are carried out by artificial insemination and multiple ovulation embryo transfer (MOET).
The artificial method of animal breeding is best as it ensures good quality of progeny. It is also economic and time saving process to obtain the desirable progeny.

Question. How are biofortified maize and wheat considered nutritionally improved? 
Answer. Biofortified maize has twice the amount of amino acids, lysine and tryptophan, compared to existing hybrids and the wheat variety has increased protein content.

Question. Differentiate between inbreeding and heterosis. What is inbreeding depression?
Answer. Table 9.7: Differences between inbreeding and heterosis

The loss of vigour/fertility and productivity due to continuous inbreeding especially close inbreeding is called inbreeding depression.

Question. Write the importance of bagging of unisexual flowers in crop improvement programme.
Answer. The emasculated flowers are covered with a bag of butter paper to prevent contamination of stigma with unwanted pollen. This process is called bagging. When this stigma attains receptivity, mature pollen grains are dusted on the stigma and the flowers are rebagged to allow the fruits to develop.

Question. What are the major advantages of producing plants by micropropagation?
Answer. Major advantages of producing plants by micropropagation are:
(i) Large number of plants can be grown in short time.
(ii) Disease-free plants can be obtained.
(iii) Plants that have lost the capacity to produce seeds can be grown.
(iv) The plants where sexual reproduction is absent, may be hybridised by tissue culture.
(v) Plants produced are genetically similar to the parent and have all its characteristics.

Question. Identify ‘A’, ‘B’, ‘C’ and ‘D’ in the given table.
Answer. 

Question. Keeping beehives in crop fields has several advantages. List any two. 
Answer. (i) Pollination management
(ii) Versatile use of resources
(iii) Honey production at no cost

Question. (a) Why are the plants raised through micropropagation termed as somaclones?
(b) Mention two advantages of this technique. 
Answer. (a) Plants raised through micropropagation are genetically identical, hence the name somaclones.
(b) (i) Large number of plants are produced in short duration.
(ii) Virus-free plants are produced.

Question. (i) Mention the property that enables the explants to regenerate into a new plant.
(ii) A banana herb is virus-infected. Describe the method that will help in obtaining healthy banana plants from this diseased plant. 
                                                                     ​​​​​​​                            OR
How is it possible to recover healthy banana plants from a diseased but desirable quality banana plant? Explain. 
Answer. (i) Totipotency is the ability of a cell to grow or generate the whole plant.
(ii) Healthy banana plants can be obtained from diseased plants by meristem culture. Although the plant is virus infected, the apical and axillary meristem is free of virus. The meristem is removed from the plant and grown in vitro by micropropagation. The plants produced are virus-free.

Question. Explain the advantage of cross-breeding of the two species of sugarcane in India.
Answer. Saccharum barberi, grown in north India, had poor sugar content and yield, whereas Saccharum officinarum, grown in south India, had thicker stem and higher sugar content. The sugarcane species obtained after cross breeding these two species had thick stems, high sugar, high yield and ability to grow in north India.

Question. How does culturing Spirulina solve the food problems of the growing human population?
                         ​​​​​​​                         ​​​​​​​                         OR 
“Large scale cultivation of Spirulina is highly advantageous for human population.” Explain giving two reasons.
Answer. Microbes are being grown on an industrial scale as source of good protein. Microbes like Spirulina can be grown easily on materials like waste water 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. Incidentally such utilisation also reduces environmental pollution and hence is environment friendly.

Long Answer Questions

Question. What is inbreeding depression and how is it caused in organisms? Write any two advantages of inbreeding. 
Answer. Animal inbreeding has the following advantages:
(i) It helps in evolving the pure lines of animals.
(ii) It helps in accumulation of superior genes and elimination of less desirable genes.
(iii) There is an increase in productivity in the inbred population.
Inbreeding depression stands for the inability of an organism to reproduce. It occurs due to continued inbreeding especially close inbreeding. There is reduction in fertility and productivity of the population that is inbred continuously.

Question. Differentiate between inbreeding and outbreeeding in cattle. State one advantage and one disadvantage for each one of them. 
Answer.

Question. Why is it necessary to emasculate a bisexual flower in a plant breeding programme? Mention the condition under which emasculation is not necessary. 
Answer. Emasculation is necessary to ensure that only the desired pollen grains are used for pollination and the stigma is protected from contamination, from unwanted self pollen. The anthers are removed followed by bagging so the plant now behaves as a female plant. The pollen grains from the anthers of the desired male plant can be dusted on the stigma of flower of the female plant to obtain desired results.
Emasculation is not required if the plant produces unisexual flowers.

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. Crop varieties can be made disease-resistant by conventional breeding methods or by mutation breeding. The germplasm is screened for resistance sources or mutations are introduced, followed by hybridisation of selected parents. The resulting hybrids are evaluated and tested. Finally, disease-resistant varieties are released.
Disease-resistant variety of:
(a) Wheat to leaf and stripe rust—Himgiri.
(b) Brassica to white rust—Pusa swarnim.

Question. (a) What is the programme called that is involved in improving success rate of production of desired hybrid and herd size of cattle?
(b) Explain the method used for carrying this programme for cows. 
Answer. (a) Multiple ovulation embryo transfer method/MOET.
(b) Refer to Basic Concepts Point 10 (Procedure).

Question. With advancements in genetics, molecular biology and tissue culture, new traits have been incorporated into crop plants.
Explain the main steps in breeding a new genetic variety of a crop. 
Answer. (i) Collection of variability on germplasm collection. All different wild varieties, species and relatives of cultivated species are collected and preserved.
(ii) Evaluation and selection of parents to identify plant with desirable combination of character.
Pure lines are created.
(iii) Cross hybridisation among selected parents to produce hybrids.
(iv) Selection and testing of superior recombinants. Selection among the progeny of the hybrids that have desired character combinations, superior to both the parents are self pollinated for several generations.

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