NCERT Solutions for class 12th Biology Chapter 9 Strategies for Enhancement in Food Production


Question 1. Explain in brief the role of animal husbandry in human welfare.

Sol. Animal husbandry is the agricultural practice for caring, feeding, breeding and management of livestock by applying scientific principles. Livestock includes animals like buffaloes, cows, pigs, horses, cattle, sheep, camels, goats, etc., that are useful to humans. It includes poultry farming and fisheries.

Animal husbandry is important for human welfare as:

  • The ever-increasing demand of food from animals and animal products both in terms of quality and quantity has been met by good animal husbandry practices.
  • In view of the high nutritive value of honey and its medicinal importance, there has been a remarkable growth in the practice of bee-keeping or apiculture.
  • Fishery is another flourishing industry meeting the ever-increasing demand for fish, fish products and other aquatic foods.
  • These livestock help in the proper utilisation of animal wastes, e.g., production of biogas and manure from the dung. They provide products which are used as food like meat, milk, eggs, honey, etc.
  • There are some other substances obtained from animals which are beneficial to human beings like wool, silk, leather, bees wax, etc.

Question 2. If your family owned a dairy farm, what measures would you undertake to improve the quality and quantity of milk production?

Sol. To improve the quality and quantity of milk production, one should undertake the following measures:

  • Proper feeding of the cattle with good quality and quantity of food.
  • Stringent clean and hygienic environment for housing the catties.
  • Proper medication.
  • Supply of adequate water.
  • Stringent cleanliness and hygienic conditions while milking, storage and transport of milk and its products.
  • Regular inspection.
  • Veterinary supervision at regular intervals.
  • Selection of good breeds having high yielding capacity combined with resistance to disease.
  • Quality of breed.

Question 3. What is meant by the term ‘breed’? What are the objectives of animal breeding?


  • Breed refers to a group of animals which are related by descent to each other and similar in characteristics like appearance, size, features, etc.
  • The objectives of animal breeding are:
    • Increasing the yield of animal produce such as milk, meat, egg, wool, etc.,
    • Improving the desirable qualities of the produce, i.e., superior quality of milk, meat, eggs, wool, etc.
    • Improving growth rate, resistance to various diseases and reproduction rate.
    • Increasing productive life.

Question 4. Name the methods employed in animal breeding. According to you which of the methods is best? Why?

Sol. Animal breeding is the process of selectively mating two animals of the same or different breeds with desired traits to maintain or enhance these traits in future generations.

Various methods employed in animal breeding are:

  • Inbreeding: It is the mating of more closely related individuals within the same breed for 4 to 6 generations.
  • Out-breeding: It is the breeding of the unrelated animals, which may be between individuals of the same breed but having no common ancestors for 4 to 6 generations (out-crossing) or between different breeds (cross-breeding) or different species (inter-specific hybridisation).
  • Out-crossing: This is the practice of mating of animals within the same breed, but having no common ancestors on either side of their pedigree up to 4 to 6 generations. The offspring of such a mating is known as an out-cross.
  • Cross-breeding: In this method, superior males of one breed are mated with superior females of another breed.
  • lnterspecific hybridisation: In this method, male and female animals of two different related species are mated.
  • Artificial insemination: It is a controlled breeding experiment in which semen is collected from the male that is chosen as a parent and injected into the reproductive tract of the selected female by the breeder. The semen may be used immediately or can be frozen and used at a later date. It can also be transported in a frozen form to where the female is housed. In this way, desirable matings are carried.
  • Multiple Ovulation Embryo Transfer Technology (MOET): In this method, a cow is administered hormones, with FSH-like activity, to induce follicular maturation and superovulation so they produce 6 to 8 eggs. The animal is either mated with an elite bull or artificially inseminated. The fertilised eggs at 8-32 cells stages, are recovered non-surgically and transferred to surrogate mothers. The genetic mother is available for another round of super ovulation.
  • Cross breeding is the best method as it results in the development of superior traits of both the breeds and the progeny produced are fertile and there is no inbreeding depression.

Note: Inbreeding depression is the reduced biological fitness in a given population as a result of inbreeding.

Question 5. What is apiculture? How is it important in our lives?


  • Apiculture, also called bee-keeping, is the rearing and breeding of honeybees for the production of honey.
  • Apiculture is important for us in the following ways:
    • It provides honey which is a food of high nutritive value and also finds use in the indigenous systems of medicine.
    • It also produces beeswax, which finds many uses in industry, such as in the preparation of cosmetics and polishes of various kinds.
    • Bees are the pollinators of many crop plants such as sunflower, Brassica, apple and pear. Keeping beehives in crop fields, during flowering period, increases pollination efficiency and improves both crop yield and honey yield.

Question 6. Discuss the role of fishery in enhancement of food production.

Sol. Fishery is the practice of rearing, catching, processing or selling of fish, shellfish or other aquatic animals. A large part of the human population is dependent on fish, fish products and other aquatic animals such as prawns, crabs, lobster, edible oysters, etc., for food. In order to meet the increasing demands on fisheries, different techniques have been employed to increase the production of aquatic plants and animals, both fresh water and marine through aquaculture and pisciculture. Also, fishes and sea food rich in protein and high nutritional value has also been produced.

Question 7. Briefly describe various steps involved in plant breeding.

Sol. 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.

  • Steps involved in plant breeding. The breeding of a new genetic variety of a crop involves the following steps:
    • Collection of variability: Firstly, all the different wild varieties, species and relatives of the cultivated species are collected and preserved. This entire collection in the form of plants or seeds having all the diverse alleles for all genes in a given crop is called germplasm collection. Germplasm collection has all the possible genetic variation which is the source of raw material for selection.
    • Evaluation and selection of parents: After collection of germplasm, it is evaluated and plants with desirable combination of characters are identified as parents. The selected parent plants are multiplied and pure lines are created wherever desirable and possible.
    • Cross hybridisation among the selected parents: In this step, selected parents with desirable characters are cross hybridised through artificial hybridisation to produce hybrids.
    • Selection and testing of superior recombinants: During this step, hybrid plants with desired character combination are selected through careful scientific evaluation of the progeny. The selected hybrid plants are self-pollinated for several generations to reach a state of uniformity (homozygosity), so that the characters will not segregate in the progeny.
    • Testing, release and commercialisation of new cultivars: The newly selected lines are grown in research fields under ideal fertiliser application, irrigation, and other crop management practices and then evaluated for their yield and other agronomic traits of quality, disease resistance, etc. This 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 where the crop is usually grown. The material is evaluated in comparison to the best available local crop cultivar – a check or reference cultivar.

Question 8. Explain what is meant by biofortification.


  • Biofortification is the breeding of crops for improved nutritional quality through both conventional plant breeding and recombinant DNA technology (genetic engineering).
  • It is undertaken to increase both bioavailability and the concentration of nutrients in crops i.e., for improved content and quality of protein, oil, vitamin, micronutrient and minerals. It is a cost-effective, feasible means of delivering micronutrients to populations who may have limited access to diverse diets, supplements, or commercially fortified foods. Thus, it is a practical means to improve public health.
  • Some of the examples of biofortified crops are Atlas 66, a wheat variety having a high protein content, an iron-fortified rice variety, vitamin A enriched carrots, spinach and pumpkin, vitamin C enriched bitter gourd, bathua, mustard, tomato, iron and calcium enriched spinach and bathua and protein enriched broad bean, lablab, French and garden peas.

Question 9. Which part of the plant is best suited for making virus-free plants and why?


  • Shoot and root apical meristems and axillary meristem can be used to obtain virus-free plants.
  • The meristems are free of virus even if the plant is infected with a virus. Hence, one can remove the meristem and grow it in vitro to obtain virus-free plants.

Question 10. What is the major advantage of producing plants by micropropagation?

Sol. Micropropagation is a method of producing a large number of plants through tissue culture.

Major advantages of this method are as follows:

  • A large number of plants are propagated in a very short duration.
  • Micropropagated plants are genetically identical to the original plant from which they were grown. Thus, desired traits can be maintained generation after generation.
  • It is possible to recover healthy plants from diseased plants by this method.
  • It gives propagules for plant multiplication throughout irrespective of the season.
  • It requires a small part of the plant called an explant and less space to generate the whole plant.
  • Genetically modified cells or cells after protoplast fusion can be multiplied through this method.

Question 11. Find out the various components of the medium used for propagation of an explant in vitro?

Sol. The nutrient medium used for propagation of explants in vitro must have the following components:

  • A carbon source such as sucrose
  • Inorganic salts
  • Vitamins
  • Amino acids
  • Growth regulators like auxins, cytokinins

Question 12. Name any five hybrid varieties of crop plants which have been developed in India.

Sol. Five hybrid varieties of crop plants developed in India are:

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