Question

Grain colour in wheat is determined by three pairs of polygenes. Following the cross AABBCC (dark colour) x aabbcc (light colour), in $F_2$ generation what proportion of the progeny is likely to resemble either parent?

• A. Half
• B. Less than 5 percent
• C. One third
• D. None of these

Answer 1

The Correct Option is B

Polygene results in quantitative inheritance which is characterised by occurrence of intermediate forms between the parental type. In case of crossing between AABBCC (dark colour) and aabbcc (light colour) in $F _{2}$ generation seven phenotypes will obtain with ratio of $1: 6: 15: 20: 15: 6: 1$. The total number of progeny is $64$, out of which only two will be likely resemble with either parents. Hence, their proportion in $F _{2}$ generation would be $3.12$ i.e., less than $5 \%$.