WAEC Biology 2025 Papers

Concept:Albinism is an autosomal recessive trait, so only the genotype $aa$ produces an albino child.Explanation:Let $A$ represent the normal allele and $a$ represent the albino allele.Both parents are heterozygous, so each has the genotype $Aa$.Each parent can produce two types of gametes: $A$ and $a$.Crossing $Aa \times Aa$ gives the possible offspring genotypes: $AA$, $Aa$, $aA$, and $aa$.Each genotype occurs with an equal probability of $\frac{1}{4}$.Only the genotype $aa$ causes albinism.Therefore, the probability that their child will be albino is $\frac{1}{4}$, or $25\%$.Answer:C. $\frac{1}{4}$