Question

The curling direction in snails is delayed a generation in its expression. The offspring of a snail are phenotypically the phenotype dictated by the genotype of the mother. Dextral curling (shell opens to the right) is dominant to sinistral curling (shell opens to the left). A cross between a homozygous sinistral female snail and a homozygous dextral male resulted in a sinistral female. If this F1 sinistral female is crossed to a homozygous sinistral male, what progeny phenotypes are expected?"

Answer 1

Answer: and  Explanation:

coiling in snails is due to maternal effect genotype of the mother determines the phenotype of the offspring. F1 sinistral female is heterozygous let the alleles be D-dextral, d-sinistral so her genotype is Dd, so she can produce mRNA for both D and d alleles so both these mRNAs cn move into the egg, the egg can be either D or d but the egg contains mRNA of D allele so the egg hen fertilized by d sperm from homozygous sinistral male develops into dextral coiling offspring since the eggs from hich these snails developed had mRNA of allele D. so the answer is all dextral