Q.1. Select the incorrect statement. (2019)
(a) Inbreeding helps in accumulation of superior genes and elimination of undesirable genes.
(b) Inbreeding increases homozygosity.
(c) Inbreeding is essential to evolve purclines, in any animal.
(d) Inbreeding selects harmful recessive gene that reduce fertility and productivity.
Inbreeding strategies allow the desirable qualities of more closely related individuals to be continued within the same breed for 4-6 generations. It increases homozygosity and thus, is necessary for evolving a pureline. Inbreeding exposes harmful recessive genes that are eliminated by selection. It also helps in accumulation of superior genes and elimination of less desirable genes. Therefore, this approach where there is selection at each step, increases the productivity of inbred population. However, continued inbreeding, especially close inbreeding usually leads to reduce fertility and even productivity. This is called inbreeding depression.
Q.2. Mad cow disease in cattle is caused by an organism which has : (2019)
(a) Inert crystalline structure
(b) Abnormally folded protein
(c) Free RNA without protein coat
(d) Free DNA without protein coat
Q.3. Homozygous purelines in cattle can be obtained by (2017)
(a) Mating of unrelated individuals of same breed
(b) Mating of individuals of different breed
(c) Mating of individuals of different species
(d) Mating of related individuals of same breed
When breeding is between animals of the same breed for 4-6 generation, it is called inbreeding. Inbreeding, as a rule, increases homozygosity. Thus, inbreeding is necessary if we want to obtain a pureline in any animal.
Q.4. A true breeding plant is (2016)
(a) One that is able to breed on its own
(b) Produced due to cross-pollination among unrelated plants
(c) Near homozygous and produces offspring of its own kind
(d) Always homozygous recessive in its genetic constitution
Q.5. Interspecific hybridisation is the mating of (2016)
(a) Animals within same breed without having common ancestors
(b) Two different related species
(c) Superior males and females of different breeds
(d) More closely related individuals within same breed for 4-6 generations.
In interspecific hybridisation, a species is mated with a different related species of the same genus. Interspecific hybrids are generally difficult to produce, but they are important in plant breeding, particularly in breeding for disease resistance. This is also called intrageneric hybridisation.
Q.6. Among the following edible fishes, which one is a marine fish having rich source of omega-3 fatty acids? (2016)
Mackerel is a marine fish, rich in omega- 3-fatty acids. Mystus, Mangur and Mrigala arc freshwater fishes.
Q.7. A system of rotating crops with legume or grass pasture to improve soil structure and fertility is called (2016)
(a) Strip farming
(b) Shifting agriculture
(c) Ley farming
(d) Contour farming
Ley farming is an agricultural system where the field is alternately seeded for grain and left fallow for growing hay or used for pasture. During the fallow/pasture period the soil is filled with roots of grasses and other plants. New ploughing mixes them in the soil and also increases the amount of nitrogen in the soil especially when legume forage are used. It also protects soil from erosion by maintaining constant soil coverage.
Q.8. A system of rotating crops with legume or grass pasture to improve soil structure and fertility is called (2016)
(a) Ley farming
(b) Contour farming
(c) Strip farming
(d) Shifting agriculture
The growing of grass or legumes in rotation with grain or tilled crops as a soil conservation measure is called Ley farming.
Q.9. Which of the following enhances or induces fusion of protoplasts ? (2015)
(a) Polyethylene glycol and sodium nitrate
(b) IAA and kinetin
(c) IAA and gibberellins
(d) Sodium chloride and potassium chloride
Polyethylene glycol and sodium nitrate play an important role in the fusion of protoplasts from the same or different species. It is done for the formation of somatic hybrid cells. This process is adopted when normal sexual reproduction is not possible for the production of hybrids.
Q.10. A technique of micropropagation is : (2015)
(a) Somatic embryogenesis
(b) Protoplast fusion
(c) Embryo rescue
(d) Somatic hybridization
Development of embryo like structure from explant by the method of tissue culture, is called somatic embryogenesis.
Q.11. Outbreeding is an important strategy of animal husbandry because it: (2015)
(a) Is useful in producing purelines of animals.
(b) Is useful in overcoming inbreeding depression.
(c) Exposes harmful recessive genes that are eliminated by selection.
(d) Helps in accumulation of superior genes.
Outbreeding is useful in the problem of inbreeding depression
Q.12. To obtain virus - free healthy plants from a diseased one by tissue culture technique, which part/parts of the diseased plant will be taken: (2014)
(a) Apical meristem only
(b) Palisade parenchyma
(c) Both apical and axillary meristems
(d) Epidermis only
To obtain virus - free healthy plants from a diseased one by tissue culture technique, both apical and axillary meristems of the diseased plant will be taken. Plant tissue culture is used to maintain or grow plant cells, tissues or organs under sterile conditions on a nutrient culture medium of known composition. Plant tissue culture is widely used to produce clones of a plant in a method known as micro propagation.