Question

A scientist crossed a pea plant with a green pod and a pea plant with a yellow pod. The scientist collected 100 seeds from the cross. The table shows the trait for pod color observed when the plants from the cross were grown. Which statement correctly explains why all the offspring have the trait for a Yellow pod? A) Genes were inherited only from the plant with a Yellow pod, so only the gene for a Yellow pod was expressed.
B) Genes were inherited only from the plant with a Green pod, but only the gene for a Yellow pod was expressed.

C) Genes for both a Green pod and a Yellow pod were inherited, but only the gene for a Yellow pod was expressed.

D) Genes for both a Green pod and a Yellow pod were inherited, so the genes for both types of pods were expressed.

Answer 1

Answer: C) Genes for both a Green pod and a Yellow pod were inherited, but only the gene for a Yellow pod was expressed.

Explanation: In a diploid organism as the pea plant, a single gene has two alleles or versions, one on each chromosome. Each of these alleles can either be dominant or recessive.

Dominant alleles, such as that producing a yellow pod, will mask the contribution to the phenotype of the second allele, which is recessive. Here, the yellow pod allele will mask the contribution of the green pod allele. Thus, the offspring will have the phenotype (pod color) yellow.

However, both alleles for pod color will be present in the offspring as each parent will provide one chromosome during sexual reproduction.