All of the following are true of the pigment melanin except that it

Correct Answer: A

Rationale: Step-by-step rationale: 1. Melanin increases in concentration during sun exposure to protect the skin. 2. Option A is incorrect as melanin actually increases in concentration to protect against UV radiation. 3. Melanin is typically brown or black (B), released through melanosomes (C), and protects DNA from UV damage (D). 4. In summary, option A is the correct answer because melanin does not decrease in concentration during sun exposure; it increases to provide protection.

Correct Answer: B

Rationale: The correct answer is B: on the palms of the hands. This is because the palms of the hands have the highest concentration of merocrine sweat glands, which are responsible for regulating body temperature by producing sweat. The palms have a higher density of these glands compared to other areas listed in the choices. A: The chest does have sweat glands, but not the highest concentration compared to the palms. C: While the axillae (armpits) have a high concentration of apocrine sweat glands, merocrine glands are more abundant on the palms. D: The upper back also contains sweat glands, but not as densely packed as on the palms. In summary, the palms of the hands have the highest concentration of merocrine sweat glands, making them the correct choice.

Correct Answer: C

Rationale: The correct answer is C: apocrine sweat glands. These glands in the axilla become active at puberty due to hormonal changes, secreting a thick, odorless substance. Sebaceous glands produce oil, ceruminous glands produce earwax, and axillary glands are not a specific type of gland. Therefore, choice C is correct as it accurately describes the glands in the axilla that are activated during puberty.

Correct Answer: A

Rationale: Step-by-step rationale for choice A being correct: 1. The papilla supplies nutrients and oxygen to the hair follicle. 2. Destruction of the papilla leads to loss of blood supply to the follicle. 3. Without blood supply, the follicle cannot sustain hair growth. 4. This results in hair production being affected. 5. Hence, the correct answer is A. Summary: - Choice B is incorrect as the color of hair is determined by melanin production in the hair bulb, not the papilla. - Choice C is incorrect as the papilla's role is crucial for hair production. - Choice D is incorrect as the type of hair produced (terminal or vellus) is determined by genetics and hormonal factors, not the papilla.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.