Suppose you cross a pea plant with yellow, smooth seeds with one that has green, wrinkled seeds. You examine the seeds of 967 offspring and find that some have yellow, smooth seeds and some have yellow, wrinkled seeds, but no green seeds of either type show up. What is the genotype of the yellow-seeded parent? (Y = yellow, y = green; S = smooth, s = wrinkled)
A) YYSs
B) YYss
C) YYSS
D) YySS
E) YySs

Question

Quizplus · Accepted Answer

The yellow-seeded parent must be homozygous for the yellow allele (YY) because no green seeds appeared among the offspring, indicating that the green allele (y) is recessive and was not contributed by the yellow-seeded parent. The presence of both smooth and wrinkled seeds among the offspring indicates that the yellow-seeded parent must have one allele for smooth seeds (S) and one for wrinkled seeds (s), making the genotype YYSs.

Suppose You Cross a Pea Plant with Yellow, Smooth Seeds