Question

In a certain species of plant, the color purple is dominant to the color white. According to the Punnett Square, what is the probability of an offspring being white?

Option 1: 25%
Option 2: 0%
Option 3: 50%
Option 4: 75%

Answer 1

The probability of offspring being white in a cross between two heterozygous purple flower plants is 25%, as deduced from the Punnett square showing one out of four possible genotypes resulting in white flowers.

Step-by-step explanation:

When predicting offspring phenotypes such as flower color in a species of plant where purple is dominant to white, we use a Punnett square. If we cross two heterozygous plants (Bb), the Punnett square would show that the genotypes of the possible offspring are BB, Bb, Bb, and bb. With the dominant allele for purple (B) and the recessive allele for white (b), only the bb genotype will result in white flowers. Therefore, as there is only one bb combination out of the four possible, the probability of an offspring being white is 25%. This matches the historical findings from Mendel's experiments with flower phenotypes in pea plants, which also produced a monohybrid cross phenotypic ratio of 3:1, favoring purple flowers.