A student crosses two pea plants. In this species, the allele for axial flowers is dominant to the allele for terminal flowers. One of the plants that the student uses in the cross is homozygous dominant for axial flowers. The other is heterozygous, which means that it has one allele for axial flowers and one allele for terminal flowers.

Question

A student crosses two pea plants. In this species, the allele for axial flowers is dominant to the allele for terminal flowers. One of the plants that the student uses in the cross is homozygous dominant for axial flowers. The other is heterozygous, which means that it has one allele for axial flowers and one allele for terminal flowers.

If the student examines 200 offspring pea plants from this cross, which of the following is a reasonable result?
A.
47 with axial flowers, 153 with terminal flowers
B.
98 with axial flowers, 102 with terminal flowers
C.
200 with axial flowers, 0 with terminal flowers
D.
149 with axial flowers, 51 with terminal flowers

Answer 1

The correct answer is D.

According to the cross, if one plant is homozygous dominant for axial flowers (AA) and the other is heterozygous (Aa), we would expect all of their offspring to have axial flowers, as the dominant allele for axial flowers will mask the recessive allele for terminal flowers. Therefore, all 200 offspring would have axial flowers (AA or Aa) and none would have terminal flowers.