The leaf color of a certain plant is controlled by one gene.For that gene,the allele G = orange and g = green.You have a plant with orange leaves,but do not know whether that plant's genotype is GG or Gg.Which of the following would help you determine the plant's genotype?
A) Cross the plant to another plant with orange leaves.
B) Cross the plant to a plant with green leaves.
C) Cross two true-breeding,orange-leaved plants to each other and then cross one of their offspring to the plant with the unknown genotype.
D) Change the environment in which the plant grows to find the conditions that cause the leaves to produce the orange color.

Question

Quizplus · Accepted Answer

Crossing the plant with an unknown genotype (either GG or Gg) with a plant that has green leaves (gg) would allow you to determine the genotype of the original plant. If any of the offspring have green leaves, the original plant must be heterozygous (Gg), because the green allele is recessive and must come from both parents to be expressed. If all offspring have orange leaves, the original plant is likely homozygous dominant (GG).

The Leaf Color of a Certain Plant Is Controlled by One