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 recessive trait would not be linked to multiple genes and loci as described.
• Codominance is about both alleles being expressed simultaneously, not relevant here.
• A dominant trait depending on only one allele doesn't match the mention of three genes and over 20 loci.
• A polygenic trait is influenced by multiple genes (alleles of several genes), which aligns with the description of glaucoma being linked to three genes and more than 20 genetic loci.

Answer:

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