Question
Fifty percent of the offspring produced by a cross between pea plants have seeds with a wrinkled (r) appearance caused by the presence of a homozygous recessive gene. What were the genotypes of the parents?
A.
Rr × Rr
B.
Rr × rr
C.
RR × Rr
D.
RR × rr
A.
Rr × Rr
B.
Rr × rr
C.
RR × Rr
D.
RR × rr
Answers
GPT 3.5
C. RR × Rr
If 50% of the offspring have wrinkled seeds caused by a homozygous recessive gene, then one of the parents must have the genotype rr. This parent can only pass on the recessive allele. The other parent must have at least one dominant allele, which can be either Rr or RR. Since the offspring have a 1:1 ratio of wrinkled (rr) to non-wrinkled (Rr or RR) seeds, it is likely that the other parent has the genotype Rr. Therefore, the genotypes of the parents were RR × Rr.
If 50% of the offspring have wrinkled seeds caused by a homozygous recessive gene, then one of the parents must have the genotype rr. This parent can only pass on the recessive allele. The other parent must have at least one dominant allele, which can be either Rr or RR. Since the offspring have a 1:1 ratio of wrinkled (rr) to non-wrinkled (Rr or RR) seeds, it is likely that the other parent has the genotype Rr. Therefore, the genotypes of the parents were RR × Rr.