NCERT Solutions for Class 12 Biology Chapter 9
Strategies for Enhancement in Food Production Class 12
Chapter 9 Strategies for Enhancement in Food Production Exercise Solutions
Exercise : Solutions of Questions on Page Number : 178
Explain in brief the role of animal husbandry in human welfare.
If your family owned a dairy farm, what measures would you undertake to improve the quality and quantity of milk production?
Dairy farm management deals with processes which aim at improving the quality and quantity of milk production. Milk production is primarily dependent on choosing improved cattle breeds, provision of proper feed for cattle, maintaining proper shelter facilities, and regular cleaning of cattle.
Choosing improved cattle breeds is an important factor of cattle management. Hybrid cattle breeds are produced for improved productivity. Therefore, it is essential that hybrid cattle breeds should have a combination of various desirable genes such as high milk production and high resistance to diseases. Cattle should also be given healthy and nutritious food consisting of roughage, fibre concentrates, and high levels of proteins and other nutrients.
What is meant by the term 'breed'? What are the objectives of animal breeding?
A breed is a special variety of animals within a species. It is similar in most characters such as general appearance, size, configuration, and features with other members of the same species. Jersey and Brown Swiss are examples of foreign breeds of cattle. These two varieties of cattle have the ability to produce abundant quantities of milk. This milk is very nutritious with high protein content.
(i) To increase the yield of animals.
(ii) To improve the desirable qualities of the animal produce.
(iii)
Name the methods employed in animal breeding. According to you which one of the methods is best? Why?
Animal breeding is the method of mating closely related individuals. There are several methods employed in animals breeding, which can be classified into the following categories:
(A) Natural methods of breeding include inbreeding and out-breeding. Breeding between animals of the same breed is known as inbreeding, while breeding between animals of different breeds is known as out-breeding. Out-breeding of animals is of three types:
(a). Out-crossing: In this type of out-breeding, the mating of animals occurs within the same breed. Thus, they have no common ancestors up to the last 4-5 generations.
(b). Cross-breeding: In this type of out-breeding, the mating occurs between different breeds of the same species, thereby producing a hybrid.
(c). Interspecific hybridization: In this type of out-breeding, the mating occurs between different species.
(B) Artificial methods of breeding include modern techniques of breeding. It involves controlled breeding experiments, which are of two types:-
(a). Artificial insemination: It is a process of introducing the semen (collected from the male) into the oviduct or the uterus of the female body by the breeder. This method of breeding helps the breeder overcome certain problems faced in abnormal mating.
(b). Multiple ovulation embryo technology (MOET): It is a technique for cattle improvement in which super-ovulation is induced by a hormone injection. Then, fertilization is achieved by artificial insemination and early embryos are collected. Each of these embryos are then transplanted into the surrogate mother for further development of the embryo.
What is apiculture? How is it important in our lives?
Discuss the role of fishery in enhancement of food production.
Briefly describe various steps involved in plant breeding.
Plant breeding is the process in which two genetically dissimilar varieties are purposely crossed to produce a new hybrid variety. As a result, characteristics from both parents can be obtained in the hybrid plant variety. Thus, it involves the production of a new variety with the desired characteristics such as resistance to diseases, climatic adaptability, and better productivity. The various steps involved in plant breeding are as follows:
(a). Collection of genetic variability: Genetic variability from various wild relatives of the cultivated species are collected to maintain the genetic diversity of a species. The entire collection of the diverse alleles of a gene in a crop is called the germplasm collection.
(b). Evaluation of germplasm and selection of parents: The germplasm collected is then evaluated for the desirable genes. The selected plants with the desired genes are then used as parents in plant breeding experiments and are multiplied by the process of hybridization.
(c). Cross-hybridization between selected parents: The next step in plant breeding is to combine the desirable characters present in two different parents to produce hybrids. It is a tedious job as one has to ensure that the pollen grains collected from the male parent reach the stigma of the female parent.
(d). Selection of superior hybrids: The progenies of the hybrids having the desired characteristics are selected through scientific evaluation. The selected progenies are then self-pollinated for several generations to ensure homozygosity.
(e).
Explain what is meant by biofortification.
Which part of the plant is best suited for making virus-free plants and why?
Apical and axillary meristems of plants is used for making virus-free plants. In a diseased plant, only this region is not infected by the virus as compared to the rest of the plant region. Hence, the scientists remove axillary and apical meristems of the diseased plant and grow it in vitro to obtain a disease-free and healthy plant.
What is the major advantage of producing plants by micropropagation?
Micropropagation is a method of producing new plants in a short duration using plant tissue culture. Some major advantages of micropropagation are as follows:
(a) Micropropagation helps in the propagation of a large number of plants in a short span of time.
(b) The plants produced are identical to the mother plant.
(c)
Find out what the various components of the medium used for propagation of explants in vitro are?
Name any five hybrid varieties of crop plants which have been developed in India.
The five hybrid varieties of crop plants which have been developed in India are:
Crop plant |
Hybrid variety |
Wheat |
Sonalika and kalian sona |
Rice |
Jaya and Ratna |
Cauliflower |
Pusa shubra and Pusa snowball K-1 |
Cowpea |
Pusa komal |
Mustard |
Pusa swarnim |