Question

Fill in the blanks in the given paragraph by selecting the correct option.
Inbreeding increases (i). Thus, inbreeding is necessary if we want to evolve a (ii) in any animal. Inbreeding exposes harmful (iii) genes that are eliminated by selection.

(a) (i) heterozygosity (ii) pure line (iii) dormant
(b) (i) heterozygosity (ii) breed (iii) recessive
(c) (i) homozygosity (ii) pure line (iii) recessive
(d) (i) homozygosity (ii) pure line (iii) dominant

Answer 1

When breeding is carried out between the same breed of animals it is known as inbreeding. It is carried out in animal husbandry to gain stronger and more beneficial animals, as the offspring tends to be superior.

Complete answer:
- Inbreeding is carried out in animal husbandry and livestock breeding by mating very closely related individuals of the same breed for 4 to 6 generations.
- Inbreeding is strategized to produce healthy, potent offspring and most importantly, pure lines of the desired characteristics.
- Inbreeding causes homozygosity. It also reveals recessive alleles in the offspring initially, which can be eliminated by separating the offspring or outcrossing.

Additional Information: - Inbreeding also leads to the accumulation of superior genes aiding in the formation of healthier offspring.
- However, continued inbreeding, especially closely, may lead to what is known as inbreeding depression. It causes the reduced fitness of a population that is the result of inbreeding.
- To combat this, the selected animals should be mated with unrelated superior animals from the same breed. This usually restores fitness and fertility.

So, the correct answer is ‘(i) homozygosity (ii) pure line (iii) recessive.’

Note: - Inbreeding also occurs in plants naturally in the form of self-pollination.
- Inbred plant lines are required as stocks or parents to produce hybrid lines that have their own set of benefits.
- Inbreeding in the case of cattle is carried out to produce female offspring (cows) that produce more and better quality of milk, while the male offspring (bulls) are potent and help in producing superior offspring.
- Inbreeding in humans is complicated, where generally it leads to genetic disorders and immunodeficiencies.