Final answer:
Dr. Terhune's green eyes and brown hair are descriptions of her phenotype, which are observable traits determined by her genotype and influenced by interactions with the environment. The dominant allele for brown hair and possibly green eyes (if considered dominant in this context) are expressed in her phenotype.
Step-by-step explanation:
The description of Dr. Terhune having green eyes and brown hair pertains to her phenotype, which is the term used to describe the observable traits of an organism. These traits are the physical expressions resulting from the interactions of the genotype, which is the underlying genetic makeup, and the environment. In this case, the dominant allele for brown hair and potentially green eyes would be responsible for her phenotype, assuming that brown is dominant over blonde or red, and green is considered a dominant trait in this context (though in reality, green eye color is typically a result of a combination of multiple genes and can be a less common phenotype).
For instance, brown hair color is a result of a dominant allele, where even if there is one copy of the allele for brown hair (B) and one for a lighter color (b), the phenotype would still be brown hair due to the dominance of the brown hair allele. Similarly, for eye color, although the situation is more complex, if we simplify it to a single gene scenario, a dominant allele for green eyes over a recessive allele would result in green eyes in the phenotype of the individual.