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. a recessive trait that requires multiple recessive alleles to be expressed b. a polygenic trait that is influenced by the number of alleles present c. a codominant trait that is expressed more often when more dominant alleles are present d. a dominant trait that depends on the presence of only one of many dominant allele

The correct answer is option b, that is, a polygenic trait that is affected by the number of alleles present.

There are three genes associated with a usual form of glaucoma, so it must be the polygenic trait, that is, it comprises more than one gene. The polygenic traits are affected by the number of alleles. In this circumstance, there are more than twenty genetic loci present, which signify that there must be a larger quantity of alleles for all the loci.

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%

some scientists like gregory adcock agree with thorne's theory of regional continuity.

others, like chris stringer and ian tattersall, believe thorne's results may be contaminated or misinterpreted.