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12th Biology 2013 Set3 Delhi Board Paper Solution

Question 21

(a) Differentiate between inbreeding and outbreeding.
(b) Explain inbreeding depression and how it can be overcome.
(c) Mention two advantages of inbreeding programme in cattle.

Answer
(a) • When breeding is between animals of the same breed it is called inbreeding.
      • when crosses between different breeds are called outbreeding.
 
(b) 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, expecially close inbreeding usually reduces fertility and even productivity. This is called inbreeding dipression.
 
(c) Two advantages of inbreeding programme in cattle are
 
(i) In breeding increases homozygosity.
(ii) A superior female, in the case of cattle is the cow or buffalo hthat produces more milk per lactation, it also helps in accumulation of superior genes and elimination of less desirable gens.