Punnett square In a certain plant, red flowers are dominant over white flowers. A plant heterozygous for red flowers and a plant with white flowers are crossed. Which of the following is the expected proportion of phenotypes in the next generation?

A. 4 red, 0 white

B. 2 red, 2 white

C. 1 red, 3 white

D. 3 red, 1 white

Answer Explanation:

We use the Punnet square to find the population of the resulting offspring from the crossing of a plant heterozygous for red flowers with a plant with white flowers.

Let R be the dominant allele for red while r is the recessive allele color for red. Therefore, the phenotype for parent 1 which is heterozygous for red flower will be Rr and the second parent with white flowers will be rr.

We cross the two phenotypes in a Punnet square as follows

 

r

r

R

Rr

Rr

r

rr

rr

 

Thus, there are 2 heterozygous offspring with red flowers and 2 offspring with white flowers.

Therefore, the Correct Answer is B.