Question

More than two alternate forms of a gene present on the same locus are called (i). They are produced due to repeated (ii) of the same gene but in different directions. The well-known example is (iii).

• A.

  (i)	(ii)	(iii)
  epistatic genes	crossing over	polydactyly

• B.

  (i)	(ii)	(iii)
  multiple alleles	mutations	human blood groups

• C.

  (i)	(ii)	(iii)
  supplementary genes	mutations	hypertrichosis

• D.

  (i)	(ii)	(iii)
  linked genes	crossing over	alkaptonuria

Answer 1

Answer: (B)

Multiple alleles is a condition where more than two variants of the gene occupy the same locus. Mutation is the change in the sequence of a DNA segment. Mutation in the sequence of amino acids can result in the formation of a new allele if the changes are simple and not on many bases. Multiple alleles combine in different combination to produce different phenotypes. Such variation in phenotypes occurs due to the proteins encoded by the allele combination. The human blood group is a classic example of multiple alleles having three alleles whose combination produces four possible phenotypes: $A, \, B, \, AB, \, \& \, O$ blood group.