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's genotype is Dd, so she will produce 1/2 D eggs and 1/2 d eggs. The father's genotype is dd, so he will only produce d sperm. Therefore, the offspring will be 1/2 Dd and 1/2 dd. All of the Dd offspring will have right-coiling shells, and all of the dd offspring will have left-coiling shells.

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