Question

glaucoma is a leading cause of blindness. studies have linked a common form of glaucoma to three genes and more than 20 genetic loci. which best describes glaucoma?
○ a recessive trait that requires multiple recessive alleles to be expressed
○ a polygenic trait that is influenced by the alleles of several genes
○ a codominant trait that is expressed more often when more dominant alleles are present
○ a dominant trait that depends on the presence of only one of many dominant alleles

Explanation:

A polygenic trait is influenced by multiple genes. Since glaucoma is linked to three genes and more than 20 genetic loci, it fits the definition of a polygenic trait. A recessive trait (first option) would focus on recessive alleles, but the question emphasizes multiple genes. Codominant (third option) involves both alleles being expressed equally, which isn't indicated here. A dominant trait (fourth option) depending on one dominant allele is incorrect as multiple genes are involved.

Answer:

a polygenic trait that is influenced by the alleles of several genes