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:

Polygenic traits are influenced by multiple genes (and loci). Glaucoma is linked to three genes and over 20 genetic loci, so it's polygenic. Recessive (needs two recessive alleles), codominant (both alleles expressed), and dominant (one dominant allele) don't fit as they involve fewer gene influences.

Answer:

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