Question

in a monohybrid cross between two heterozygous parents (bb), what is the probability of an offspring having the homozygous recessive genotype (bb)?

Explanation:

Step1: Create Punnett square grid

Set up a 2x2 grid, with gametes (B, b) from each heterozygous parent (Bb) along the top and left sides.

$$\begin{array}{c|cc} & B & b \\ \hline B & BB & Bb \\ b & Bb & bb \\ \end{array}$$

Step2: Count homozygous recessive genotypes

Identify the number of offspring with genotype bb: 1 out of 4 total genotypes.

Step3: Calculate probability

Divide the count of bb by total genotypes, convert to percentage.
$\text{Probability} = \frac{1}{4} \times 100\% = 25\%$

Answer:

25%