JAMB Biology 2019 Paper

Concept:Albinism is an inherited condition that appears only when an individual carries two copies of a recessive allele.Explanation:Albinism is a lack of the pigment melanin in the skin, hair, and eyes.The gene controlling pigmentation has a dominant allele $\mathrm{A}$ and a recessive allele $\mathrm{a}$.Individuals with genotype $\mathrm{AA}$ or $\mathrm{Aa}$ have normal pigmentation, because the dominant allele masks the recessive allele.Only the genotype $\mathrm{aa}$ produces albinism.This inheritance pattern is typical of a recessive trait, not a dominant one.It is not directly caused by whole chromosomes or by a new mutation arising in the individual.Therefore, albinism is an expression of a trait controlled by recessive genes.Answer:B. Recessive genes