[Campbell Biology P.360] In a reciprocal cross between two primrose varieties, the following... | Practice Question

In a reciprocal cross between two primrose varieties, the following results are obtained: Cross 1: Female A × Male B → All offspring have green leaves. Cross 2: Female B × Male A → All offspring have patterned variegated leaves. What do these results suggest?

  • A: The green-leaf allele is dominant over the patterned-leaf allele.
  • B: The trait is controlled by a gene in the plastids (chloroplasts).
  • C: The gene for this trait is X-linked.
  • D: The trait is determined by genomic imprinting.

Explanation

This is a classic example of maternal inheritance. The fact that the offspring's phenotype always matches the phenotype of the female parent the source of the egg and its cytoplasm regardless of the male parent indicates that the gene controlling the trait is located in the cytoplasm, specifically in the plastids chloroplasts , which are inherited from the mother.