Question

the allele for normal hemoglobin (h) is dominant to the allele for sickle - cell hemoglobin (h). a male and female who are both heterozygous for sickle - cell hemoglobin have a child. what is the chance that this child will have a sickle - cell hemoglobin? multiple choice 100% 25% 75% 0% 50%

Explanation:

Step1: Identify parental genotypes

Both parents are heterozygous: $Hh$

Step2: Set up Punnett square

$$\begin{array}{c|cc} & H & h \\ \hline H & HH & Hh \\ h & Hh & hh \\ \end{array}$$

Step3: Calculate affected offspring ratio

Sickle-cell requires $hh$. 1 out of 4 genotypes is $hh$.
$\frac{1}{4} = 25\%$

Answer:

25%