Question

A strain of a cereal grain can be either dark tan, medium-dark tan, medium tan, light tan, or cream colored. When a dark tan and a cream plant are crossed, all F1 are medium tan. The F2 are distributed in a ratio of 1:4:6:4:1 from darkest to lightest. How many genes are involved in this coloration?

Answer 1

Answer:

The correct answer is - 2 genes.

Explanation:

The number of genes involved in the coloration of the strain of cereal grain, could be either dark tan, medium-dark tan, medium tan, light tan, or cream-colored if all F1 are medium tan when crossed a dark tan crossed with cream-colored, can be calculated as follow:

suppose there are only two gene - TT dominant over tt and CC dominant over cc

then the cross would be - RRCC - rrcc

gametes - RC and rc

Cross F1: RrCc

Self cross in F2:

offspring by Punnet cross are:

RRCC  -->1/16  

RRCc,  RrCC .---> 4/16

RrCc, RRcc, rrCC--->6/16

rrCc, Rrcc--->4/16

rrcc ----> 1/16

thus, the correct answer is 2 genes