Question

A maternal effect can cause the offspring phenotype ratio to depart from that of classic Mendelian inheritance. In a species of moth, the dominant allele N codes for brown eyes and recessive allele n codes for red eyes.
If an Nn female with brown eyes mates with an Nn male, what is the eye color phenotypic ratio of their offspring?

Answer 1

Maternal effect

Explanation:

In maternal effect the phenotype of the progeny is decided by the genotype of the mother

• The female partner is one step ahead to her male partner
• The ovum transcribes some of its nuclear genes prior to fertilization and these genes are responsible for the development of embryo that is why these genes are called maternal effect genes
• This effect is observed in Drosophila

In the given question both male and female have brown eyes with Nn genotype,phenotype of the offspring will be decided by the genotype of mother(Nn) hence despite of having recessive genotype(nn) all the offsprings will show brown eyes