Question

The purple (P) allele of a flower color gene is dominant to the white (p) allele. If two heterozygous plants are crossed,________. of their progeny will have purple flowers. Note: to receive credit for your answer, it must be a whole number (e.g. 10) as opposed to a word (e.g. ten) and must not contain % or percent. In other words, 10 would be a correct answer while ten, 10%, or ten percent would not. No credit will be given to answers that do not conform to these guidelines.

Answer 1

When two heterozygous plants with a dominant purple allele are crossed, 75 of the progeny will have purple flowers, calculated using a Punnett square analysis with a phenotypic ratio of 3:1 for purple to white flowers.

Step-by-step explanation:

When two heterozygous plants with the purple allele (P) being dominant over the white allele (p) are crossed, the expected phenotypic ratio of their progeny regarding flower color is 3:1. That means three out of every four offspring will have purple flowers. This is derived from performing a Punnett square analysis, where crossing two heterozygotes (Pp x Pp) yields genotypes PP, Pp, Pp, and pp. Therefore, the probability of the offspring having a purple flower (either PP or Pp genotype) is 75.

The Punnett square can be used to demonstrate that the genotypic ratio will be 1 PP (homozygous dominant), 2 Pp (heterozygous), and 1 pp (homozygous recessive). However, because purple is the dominant flower color, both PP and Pp individuals will exhibit a purple flower phenotype, while only pp individuals will have white flowers.