JAMB Biology 2024 Paper

Concept:A cross between a heterozygous red plant ($Rr$) and a white plant ($rr$) follows simple Mendelian inheritance, giving the chance of each genotype among the offspring.Explanation:The red plant produces two types of gametes: $R$ and $r$.The white plant produces only one type of gamete: $r$.Combine the gametes to form the offspring genotypes:$$Rr,\; rr,\; Rr,\; rr$$There are $4$ possible outcomes in total.Out of these, $2$ are heterozygous red ($Rr$).So the probability of an offspring being $Rr$ is:$$\frac{2}{4} = \frac{1}{2}$$Answer:A. $\;\frac{1}{2}$