Exposure to ultraviolet light causes the skin to darken by stimulating the
A)breakdown of carotene.
B)breakdown of melanin.
C)activity of the keratinocytes.
D)activity of the enzyme tyrosinase.
E)buildup of bilirubin.

Question

Quizplus · Accepted Answer

The enzyme tyrosinase is responsible for the production of melanin in the skin, which is responsible for skin pigmentation. When the skin is exposed to ultraviolet light, it stimulates the activity of the enzyme tyrosinase, leading to an increase in melanin production and thus skin darkening. A and E are incorrect as they are not involved in skin pigmentation. Activity of keratinocytes is not directly involved in the production of melanin, but rather in the maintenance of the skin barrier. B is incorrect because although melanin breakdown does occur over time, it is not responsible for skin darkening in response to UV light.

Exposure to Ultraviolet Light Causes the Skin to Darken by Stimulating