A Gene for Eye Color in Humans Has 3 Alleles

question 200

Multiple Choice

A gene for eye color in humans has 3 alleles: E^B, E^Bl, and E^G, for brown, blue, and green eyes, respectively. If an individual is E^B/E^G, is she homozygous or heterozygous for eye color?

• A)Neither, because the genotype is incomplete without an allele for brown eye color
• B)Neither, because with more than two possible alleles for a gene, heterozygous and homozygous don't mean anything
• C)Heterozygous
• D)Homozygous

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Definitions:

Epiblast

An early embryo layer from which all the three primary germ layers develop during gastrulation in the formation of a vertebrate body.

Notochord

A flexible rod-like structure in the early stages of embryos in all chordates, providing skeletal support.

Blastocoel

The fluid-filled cavity of a blastula.

Archenteron

The primitive gut formed during the early development of an embryo, which later differentiates into the digestive tract of an animal.