Question

Which of the following describes the genotype and phenotype of parents whose child will definitely have a recessive trait? A. Both parents are homozygous for the recessive allele and have the trait. B. Both parents are homozygous for the recessive allele but do not have the trait. C. Both parents are heterozygous for the recessive allele and have the trait. D. Both parents are heterozygous for the recessive allele but do not have the trait.

Answer 1

The answer is; A

When both parents are homozygous recessive, then there is 99.9 percent chances that offspring will bear the recessive trait. The offspring will also be homozygous recessive. This can be demonstrated by the following punnet square (assume dominant allele is assigned letter B while recessive allele b).