If a trait is recessive and masked by a dominant trait, what does this indicate about its expression?

If a trait is recessive and masked by a dominant trait, what does this indicate about its expression?

• A. It is expressed when paired with a dominant allele
• B. It is masked by a dominant trait
• C. It appears in every generation
• D. It is inherited only from the mother

Answer: (B)

Dominant alleles hide recessive ones in the phenotype whenever at least one dominant allele is present. So a recessive trait will only be visible when both alleles are recessive (two recessive copies). That’s why it is masked when a dominant trait is present—the recessive form shows up only in the absence of a dominant allele. It isn’t expressed in every generation and it isn’t inherited only from the mother, since both parents contribute alleles.

Dominant alleles hide recessive ones in the phenotype whenever at least one dominant allele is present. So a recessive trait will only be visible when both alleles are recessive (two recessive copies). That’s why it is masked when a dominant trait is present—the recessive form shows up only in the absence of a dominant allele. It isn’t expressed in every generation and it isn’t inherited only from the mother, since both parents contribute alleles.