AP BIOLOGY

Detailed explanation-1: -Widow’s peak occurs when the hairline forms a distinct point in the center of the forehead. Widow’s peak is controlled by a dominant allele (W). A dominant allele (T) gives the individual the ability to curl the tongue in a U-shape.

Detailed explanation-2: -Single-gene traits include some of the most observable physical traits in humans, like eye color, widow’s peak hairline, earlobe type (attached versus detached), presence of freckles or dimples, or the ability to roll your tongue.

Detailed explanation-3: -Autosomal single-gene Traits in Humans Single-gene autosomal traits include widow’s peak and freckles, both of which are illustrated below. Widow’s peak refers to a point in the hairline at the center of the forehead.

Detailed explanation-4: -Assuming that you’re referring to single-gene traits, a single-gene trait is a trait that is controlled by only one gene. An example in humans is whether you have a widow’s peak-your hairline forming a small point over the middle of your forehead-or not.

Detailed explanation-5: -As a rule, single gene disorders (also known as Mendelian traits or diseases) are relatively uncommon. The occurrence of a disease caused by a single gene mutation may occur in several main patterns or modes. These are grouped according to whether the trait is sex-specific (generally X-linked) or not (autosomal).