Q. Grain colour in wheat is determined by three pairs of polygene. Following the cross $AABBCC(dark\ colour) \times aabbcc(light\ colour)$ , in $F_{2}$ generation. What proportion of the progeny is likely to resemble either parent?

A) Half
B) Less than 5 per cent
C) One –third
D) None of these
Explanation

Polygene results in quantitative inheritance, which is characterized by occurrence of intermediate forms between the parental type. In case of crossing between AABBCC (dark colour) and aabbcc (light colour), in F2-generation seven phenotypes will obtain with ratio 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 F2-generation would be 3.12, i.e., less than 5%

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.