PATHOLOGY

Detailed explanation-1: -The heterozygous condition carries both dominant and recessive alleles, the presence of dominant allele masks the expression of the recessive allele. So, recessive alleles can be expressed only in homozygous conditions of any generation. The correct answer is B.

Detailed explanation-2: -A dominant allele produces a dominant phenotype in individuals who have one copy of the allele, which can come from just one parent. For a recessive allele to produce a recessive phenotype, the individual must have two copies, one from each parent.

Detailed explanation-3: -The most common interaction between alleles is a dominant/recessive relationship. An allele of a gene is said to be dominant when it effectively overrules the other (recessive) allele. Eye colour and blood groups are both examples of dominant/recessive gene relationships.