In a test cross, peas of an unknown genotype are crossed with peas of a known genotype. In this example, smooth peas are the unknown and wrinkled peas are the known (rr). If half of the offspring from that cross are smooth and half are wrinkled, what is the genotype of the unknown plant?
A) Incomplete dominance
B) Homozygous dominant: RR
C) Homozygous recessive: rr
D) Heterozygous: Rr
E) The genotype cannot be determined from the information given.

Question

Quizplus · Accepted Answer

The unknown smooth pea plant must be heterozygous (Rr) because crossing it with a homozygous recessive (rr) results in a 1:1 ratio of smooth (Rr) to wrinkled (rr) offspring.

In a Test Cross, Peas of an Unknown Genotype Are