A certain kind of snail can have a right-handed direction of shell coiling (D)or left handed coiling (d). If direction of coiling is due to a protein deposited by the mother in the egg cytoplasm, then a Dd egg-producing snail and a dd sperm-producing snail will have offspring of which genotype(s)and phenotype(s)?
A)1/2 Dd : 1/2 dd; all right coiling
B)All Dd; all right coiling
C)1/2 Dd : 1/2 dd; half right and half left coiling
D)All Dd; all left coiling
E)All Dd; half right and half left coiling

Question

Quizplus · Accepted Answer

The mother snail is Dd, which means she can produce both D and d gametes. The father snail is dd, which means he can only produce d gametes. Therefore, the offspring will be either Dd or dd. Since the direction of coiling is determined by the protein deposited by the mother, all of the offspring will have right-handed coiling.

A Certain Kind of Snail Can Have a Right-Handed Direction