NCERT Solutions for Class 12 Biology Strategies for Enhancement in Food Production [Old book]

NCERT
SOLUTIONS
CLASS - 12th

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Class : 12th
Subject : Biology
Chapter : 9
Chapter Name : Strategies for Enhancement in Food Production

Q1 Explain in brief the role of animal husbandry in human welfare.

Answer. Animal husbandry deals with the scienti c management of livestock. It includes various
aspects such as feeding, breeding, and control diseases to raise the population of animal livestock.
Animal husbandry usually includes animals such as cattle, pig, sheep, poultry, and sh which are
useful for humans in various ways. These animals are managed for the production of commercially
important products such as milk, meat, wool, egg, honey, silk, etc. The increase in human
population has increased the demand of these products. Hence, it is necessary to improve the
management of livestock scienti cally.

Q2 If your family owned a dairy farm, what measures would you undertake to improve the quality
and quantity of milk production?

Answer. 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, bre concentrates, and high levels of proteins and other nutrients. Cattle's should be
housed in proper cattle-houses and should be kept in well ventilated roofs to prevent them from
harsh weather conditions such as heat, cold, and rain. Regular baths and proper brushing should
be ensured to control diseases. Also, time-to-time check ups by a veterinary doctor for symptoms
of various diseases should be undertaken.

Q3 What is meant by the term 'breed'? What are the objectives of animal breeding?

Answer. A breed is a special variety of animals within a species. It is similar in most characters
such as general appearance, size, con guration, 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.
Objectives of animal breeding:
(i) To increase the yield of animals.
(ii) To improve the desirable qualities of the animal produce.
(iii) To produce disease-resistant varieties of animals.

Q4 Name the methods employed in animal breeding. According to you which one of the methods
is best? Why?

Answer. Animal breeding is the method of mating closely related individuals. There are several
methods employed in animals breeding, which can be classi ed into the following categories:
(A) Natural methods of breeding include inbreeding and outbreeding. Breeding between animals
of the same breed is known as inbreeding, while breeding between animals of different breeds is
known as outbreeding. Out- breeding of animals is of three types:
(a). Outcrossing: 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). Interspeci c hybridization: In this type of out-breeding, the mating occurs between different
species.

(B) Arti cial methods of breeding include modern techniques of breeding. It involves controlled
breeding experiments, which are of two types:-
(a). Arti cial 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
arti cial insemination and early embryos are collected. Each of these embryos are then
transplanted into the surrogate mother for further development of the embryo. The best method
to carry out animal breeding is the arti cial method of breeding, which includes arti cial
insemination and MOET technology. These technologies are scienti c in nature. They help
overcome problems of normal mating and have a high success rate of crossing between mature
males and females. Also, it ensures the production of hybrids with the desired qualities. This
method is highly economical as a small amount of semen from the male can be used to inseminate
several cattle.

Q5 What is apiculture? How is it important in our lives?

Answer. Apiculture is the practice of beekeeping for the production of various products such as
honey, bee's wax, etc. Honey is a highly nutritious food source and is used as an indigenous system

of medicines. It is useful in the treatment of many disorders such as cold, u, and dysentery. Other
commercial products obtained from honey bees include beeswax and bee pollen. Bee's wax is used
for making cosmetics, polishes, and is even used in several medicinal preparations. Therefore, to
meet the increasing demand of honey, people have started practicing beekeeping on a large scale.
It has become an income generating activity for farmers since it requires a low investment and is
labour intensive.

Q6 Discuss the role of shery in enhancement of food production.

Answer. Fishery is an industry which deals with catching, processing, and marketing of shes and
other aquatic animals that have a high economic value. Some commercially important aquatic
animals are prawns crabs, oysters, lobsters, and octopus. Fisheries play an important role in the
Indian economy. This is because a large part of the Indian population is dependent on shes as a
source of food, which is both cheap and high in animal protein. A Fishery is an employment
generating industry especially for people staying in the coastal areas. Both freshwater shes (such
as Catla, Rohu, etc) and marine shes (such as tuna, mackerel pomfret, etc.) are of high economic
value.

Q7 Brie y describe various steps involved in plant breeding.

Answer. 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 scienti c evaluation. The selected progenies are then self-pollinated for
several generations to ensure homozygosity.
(e). Testing, release, and commercialization of new cultivars: The selected progenies are evaluated
for characters such as yield, resistance to diseases, performance, etc. by growing them in research

elds for at least three growing seasons in different parts of the country. After thorough testing
and evaluation, the selected varieties are given to the farmers for growing in elds for a large-scale
production.

Q8 Explain what is meant by bioforti cation.

Answer. Bioforti cation is a process of breeding crops with higher levels of vitamins, minerals,
proteins, and fat content. This method is employed to improve public health. Breeding of crops
with improved nutritional quality is undertaken to improve the content of proteins, oil, vitamins,
minerals, and micronutrients in crops. It is also undertaken to upgrade the quality of oil and
proteins. An example of this is a wheat variety known as Atlas 66, which has high protein content
in comparison to the existing wheat. In addition, there are several other improved varieties of crop
plants such as rice,carrots, spinach etc. which have more nutritious value and more nutrients than
the existing varieties.

Q9 Which part of the plant is best suited for making virus-free plants and why?

Answer. 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. Virus-free plants of banana, sugarcane, and
potato have been obtained using this method by scientists.

Q10 What is the major advantage of producing plants by micropropagation?

Answer. 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) It leads to the production of
healthier plantlets, which exhibit better disease-resisting powers.

Q11 Find out what the various components of the medium used for propagation of explants in
vitro are?

Answer. The major components of medium used for propagation of explants in vitro are carbon
sources such as sucrose, inorganic salts, vitamins, amino acids, water, agar-agar, and certain
growth hormones such as auxins and gibberellins.

Q12 Name any ve hybrid varieties of crop plants which have been developed in India.

Answer. The ve hybrid varieties of crop plants which have been developed in India are: