Question

two plants are heterozygous for seed shape and have round seeds. if the two plants are crossed, what is the probability that the offspring will have wrinkled seeds?
25 percent
50 percent
75 percent
100 percent

Explanation:

Step1: Define allele notation

Let $R$ = dominant (round) allele, $r$ = recessive (wrinkled) allele. Heterozygous plants have genotype $Rr$.

Step2: Set up Punnett square

Cross $Rr \times Rr$. The Punnett square is:

$$\begin{array}{c|cc} & R & r \\ \hline R & RR & Rr \\ r & Rr & rr \\ \end{array}$$

Step3: Calculate wrinkled genotype ratio

Wrinkled seeds require $rr$ genotype. 1 out of 4 genotypes is $rr$.

Step4: Convert to percentage

$\frac{1}{4} \times 100 = 25\%$

Answer:

25 percent