Question

You have two true-breeding plants, one with red flowers and one with blue flowers. You cross these plants and produce 1000 offspring: 249 red-flowered offspring, 252 blue-flowered offspring, and 501 offspring which express both of the parental phenotypes by having red and blue striped flowers. Which of the following patterns of inheritance best explains the results you observed?
A. The red pigment allele is completely dominant over the blue pigment allele.
B. The blue pigment allele is incompletely dominant over the red pigment allele.
C. The red and blue pigment alleles are codominant.
D. Blue pigment production is controlled a temperature sensitive allele.

Answer 1

Answer:

C. The red and blue pigment alleles are codominant.

Explanation:

This pattern of inheritance described in the question is referred to as CODOMINANCE, which is a non-mendelian pattern of inheritance in which one allele of a gene is neither dominant nor recessive to the other allele, hence, both alleles are phenotypically expressed in the heterozygous state.

This is the case of the red and blue pigment alleles in this question. When two true-breeding parents (red and blue pigment) are crossed, they produce some offsprings that simultaneously expresses both of their phenotypes (red and blue stripes). This is because the alleles of those pigments are both dominant in the pigment gene, hence, they are said to be CODOMINANT