Question

the trait for eye color is influenced by several pairs of alleles. therefore, there are many different shades of eye color. what mode of inheritance does this phenomenon describe?

polygenic

recessive

sex - linked

incomplete dominance

Explanation:

To determine the mode of inheritance for eye color influenced by several pairs of alleles, we analyze each option:

• Polygenic: A polygenic trait is controlled by multiple (several) genes (pairs of alleles), and it results in a range of phenotypes (many different shades of eye color), which matches the description.
• Recessive: A recessive trait is expressed only when two recessive alleles are present, and it's typically controlled by a single gene (not multiple allele pairs), so this is incorrect.
• Sex - linked: Sex - linked traits are associated with genes on the sex chromosomes (X or Y), and the question doesn't mention any association with sex chromosomes, so this is incorrect.
• Incomplete dominance: In incomplete dominance, the heterozygous phenotype is an intermediate between the two homozygous phenotypes, and it's usually controlled by a single gene with two alleles, not several pairs of alleles, so this is incorrect.

Answer:

A. polygenic