Question

Choose the correct answer from the alternatives given.
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. Their well known example is (iii) Which of the following correctly fills the above statement?

• A. (i) - epistatic genes, (ii) - crossing over, (iii) - polydactyly
• B. (i) - multiple alleles, (ii) mutations, (iii) - human blood groups
• C. (i) supplementary genes (ii) mutations, (iii) - hypertrichosis
• D. (i) - linked genes, (ii) - crossing over, (iii) - alkaptonuria

Answer 1

Answer: (B)

Three or more alternative forms of a gene (alleles) that can occupy the same locus are called as multiple alleles. A mutation in any base pair can cause a new allele. Multiple alleles combine in different ways in a population, and produce different phenotypes. These phenotypes are caused by the proteins encoded for by the various alleles. An excellent example of multiple allele inheritance is human blood type. Blood type exists as four possible phenotypes: A, B, AB, & O. There are 3 alleles for the gene that determines blood type.

So, the correct option is '(i) - multiple alleles, (ii) mutations, (iii) - human blood groups'.