Question

which of the following is an example of an environmental factor affecting cell differentiation?
a sea turtles lay their eggs in the sand, and the sand temperature determines the gender of the hatchlings.
b due to repeated sun exposure, a lifeguard has darker colored skin at the end of the summer.
c trees lose their leaves during the winter, and regrow new leaves in the spring.
d carcinogens taken in by smoking can lead to an increased risk of developing lung cancer.

Explanation:

Cell differentiation is the process by which a cell changes from one cell type to another. In option A, the environmental factor (sand temperature) affects the development (which involves cell - differentiation processes) of sea turtle hatchlings to determine their gender. Option B is about a change in skin pigmentation due to sun exposure (a change in an existing cell type's function - melanin production, not a change in cell type through differentiation). Option C is a seasonal change in plant morphology (leaf shedding and regrowth) which is more of a plant - level adaptation rather than a direct example of environmental factors affecting cell differentiation. Option D is about the effect of carcinogens on cancer development (a pathological change in cell behavior, not a normal cell - differentiation process affected by the environment).

Answer:

A. Sea turtles lay their eggs in the sand, and the sand temperature determines the gender of the hatchlings.