On the basis of shape and structure sweat glands are

Correct Answer: A

Rationale: The correct answer is A: Simple tubular. Sweat glands are classified based on their shape and structure. Simple tubular glands have a long, straight tube for secretion, which matches the structure of sweat glands. Simple alveolar glands have a rounded sac shape, not seen in sweat glands. Compound acinar glands have a branched, sac-like structure, and compound tubular glands have a branched, tube-like structure, neither of which matches the structure of sweat glands. Therefore, the correct answer is A as sweat glands are characterized by a simple tubular structure.

Correct Answer: D

Rationale: The correct answer is D: Cortex. Melanin pigment granules are found in the cortex layer of the hair shaft. This is where the color of the hair is determined. The cortex contains the majority of the hair's melanin, which gives hair its natural color. The other choices, A: Hair follicle, B: Hair papilla, and C: Medulla, do not contain melanin pigment granules. The hair follicle is the root of the hair, the hair papilla is a structure at the base of the follicle, and the medulla is the innermost layer of the hair shaft that may or may not contain pigment depending on the hair color.

Correct Answer: B

Rationale: The correct answer is B: Elasticity of dermis decreases. As people age, the dermis layer of the skin loses collagen and elastin fibers, leading to a decrease in skin elasticity, resulting in loose and wrinkled skin. The other choices are incorrect because A (Stratum germinativum becoming more active) would actually lead to increased cell turnover and potentially smoother skin, C (Stratum corneum becoming thicker) would result in thicker skin but not necessarily loose and wrinkled, and D (poor blood supply to the skin) would affect overall skin health but not directly cause loose and wrinkled skin.

Correct Answer: B

Rationale: The correct answer is B: Involuntary. Muscles found in the skin, such as arrector pili muscles responsible for hair erection, are involuntary muscles. These muscles respond to autonomic nervous system signals without conscious control. Choice A is incorrect because muscles in the skin are not under voluntary control. Choice C is incorrect because it suggests a combination of voluntary and involuntary muscles, which is not accurate for skin muscles. Choice D is incorrect as there are indeed involuntary muscles in the skin.

Correct Answer: A

Rationale: The correct answer is A. When exposed to sunlight, the skin responds by widening the capillaries to allow more blood flow, leading to a reddish appearance. This process is known as vasodilation. Option B is incorrect as blood cells do not ooze out through skin pores. Option C is inaccurate as haemoglobin breakdown does not cause skin reddening. Option D is also incorrect since the spleen does not release more blood in response to sunlight.