Which Genotypic Ratio Indicates a Recessive Lethal Allele When Two

Question

Which genotypic ratio indicates a recessive lethal allele when two heterozygotes are mated?
A)2:1
B)3:1
C)1:2:1
D)1:1
E)4:1

Accepted Answer

When two heterozygotes are mated and there is a recessive lethal allele involved, the expected genotypic ratio is 2:1. This is because the homozygous recessive genotype, which would normally make up one quarter of the offspring, is lethal and does not survive, leaving a ratio of 2:1 of surviving offspring.