Question

In pea plants, flower color is inherited in a Mendelian fashion. Purple flowers (P) are dominant over white flowers (p). If two plants that are heterozygous for purple flowers, Pp, are crossed, what is the probability that their offspring will have white flowers?

Answer 1

25%

Explanation:

The crossing between two heterozygous purple flowers can have the following results:

P from 1st flower and P from 2nd flower: PP -> 25% chance

P from 1st flower and p from 2nd flower: Pp -> 25% chance

p from 1st flower and P from 2nd flower: Pp -> 25% chance

p from 1st flower and p from 2nd flower: pp -> 25% chance

As the purple flower gene is dominant over the white flower, to have a white flower we need to have only white flower's genes, that is, pp.

So, the probability of the offspring will have white flowers is 25%