Question

In rabbits, the color of body fat is a diet conditional trait. The mutant allele y results,in the homozygous condition, in yellow body fat with a normal xanthophyll-rich diet but white fat on a xanthophyll-free diet. The dominant wildtype allele Y results in white body fat regardless of diet. What would be the expected phenotypic ratios from the monohybrid cross with and without xanthophyll in the diet?

A.) with xanthophyll all white; without xanthophyll 3:1 white: yellow

B.) with xanthophyll all yellow; without xanthophyll 3:1 yellow:white

C.) with xanthophyll 3:1 white:yellow; without xanthophyll all white

D.) with xanthophyll 3:1 yellow:white; without xanthophyll all yellow

Answer 1

Y allele will lead to the production of white body fat regardless of the xanthophyll rich diet. So all the rabbit having the Y allele will have white body fat.

In case of mutant allele y, the rabbit will have yellow body fat if the rabbit is feed with the xanthophyll rich diet, but produce white body fat when feed wit the xanthophyll free diet.

As we can see from the cross that when a rabbit is fed with xanthophyll rich diet the ratio will be 3:1 White: yellow

When the rabbit is feed with xanthophyll free diet the all the rabbit will be white.

So the answer is option C is correct.