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

Correct Answer: B

Rationale: Correct Answer: B Rationale: 1. Melanin is produced from the amino acid tyrosine, making choice A true. 2. Melanin protects DNA from UV radiation, making choice C true. 3. Melanin is usually some shade of brown or black, making choice D true. 4. Melanin actually increases in concentration within cells during exposure to the sun to provide more protection, making choice B false. Summary: Choices A, C, and D are true statements about melanin. Choice B is incorrect as melanin increases in concentration during sun exposure.

Correct Answer: A

Rationale: The correct answer is A. Accessory structures of the integument, like hair and nails, do not provide direct protection to the skull. Skull protection primarily comes from the cranial bones and meninges. Hair and nails are involved in thermoregulation, sensation of touch, and production of skin pigments. Therefore, choice A is incorrect as the accessory structures do not directly protect the skull but serve other functions related to the integument system.

Correct Answer: A

Rationale: The correct answer is A: stratum corneum. This is the outermost layer of the epidermis composed of dead skin cells filled with keratin. It provides protection against environmental factors. Stratum spinosum (B) is a layer below the stratum corneum, stratum basale (C) is the deepest layer where cells divide, and stratum granulosum (D) is a layer above the stratum corneum where cells start to flatten and keratinize. The stratum corneum is the toughest and most superficial layer, making it the correct choice.

Correct Answer: D

Rationale: The correct answer is D: merocrine sweat glands. These glands are responsible for producing perspiration, which is a watery fluid that helps regulate body temperature. Merocrine glands release sweat directly onto the skin's surface without losing any cellular components, ensuring efficient cooling. A: Apocrine sweat glands produce a thicker, odorless substance in areas like the armpits and groin. B: Ceruminous glands produce earwax to protect the ear canal. C: Sebaceous glands produce sebum to moisturize the skin and hair. In summary, merocrine sweat glands are the correct choice as they specifically produce perspiration for cooling purposes, distinguishing them from the other gland types mentioned.

Correct Answer: B

Rationale: Carotene is the correct answer because it is a pigment present in vegetables like carrots and sweet potatoes that can give the skin an orange or yellow hue when consumed in large quantities. Chlorophyll is a green pigment found in plants for photosynthesis. Hemoglobin is a protein in red blood cells responsible for carrying oxygen. Bilirubin is a yellow pigment formed from the breakdown of red blood cells and can cause yellowing of the skin in conditions like jaundice.