Question

A purple-flowered pea plant and a white flowered pea plant were crossed. the allele for purple flowers is dominant, and the allele fro white flowers is recessive. of 1,000 offspring, were white-flowered peas plants. based on these results, which of the following can be concluded about the parent plants?

a. the white-flowered pea plant is homozygous dominant
b. the white-flowered pea plant is heterozygous
c. the purple-flowered pea plant is heterozygous
d. the purple-flowered pea plant is homozygous dominant

Answer 1

The white-flowered pea plant is homozygous recessive (bb), and the purple-flowered pea plant is heterozygous (Bb), as this combination would result in both purple and white flowered offspring.

Step-by-step explanation:

Based on the information provided, where a purple-flowered pea plant was crossed with a white-flowered pea plant and both purple and white flowered offspring resulted, we can conclude the following about the parent plants:

The white-flowered pea plant must be homozygous recessive (bb) since the only allele it can contribute is the recessive allele for white flowers. For the purple-flowered pea plant to produce any white-flowered offspring, it must also be able to contribute a recessive allele, thereby making it heterozygous (Bb). This is because only the combination of bb (from both parents) would result in a white-flowered plant, and given the purple flower color is dominant (B), the presence of even one B allele would result in a purple-flowered plant. Hence, in this cross, it is the purple-flowered pea plant that is heterozygous.