Which part of hairs have pigment granules of melanin -

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: 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.

Correct Answer: D

Rationale: The correct answer is D: Cold. Dense fur in cold temperature animals acts as insulation to retain body heat and protect them from the cold. The fur traps air close to the body, creating a layer of warmth. This helps regulate their body temperature and prevent heat loss. Snow (A) is not the main threat as the fur insulates against it. Air (B) is actually trapped by the fur to provide insulation. Enemies (C) are not directly protected against by dense fur, as it primarily serves to regulate body temperature in cold environments.

Correct Answer: D

Rationale: The correct answer is D: Stratum lucidum. This layer of the epidermis is known for its clear, translucent appearance and plays a key role in forming a barrier that prevents the entry of water and other substances into the body. It is located between the stratum corneum and the stratum granulosum. The other choices are incorrect because: A: Stratum spongiosum is not a recognized layer of the epidermis. B: Stratum granulosum is involved in the production of keratin and the formation of the skin barrier, but it is not specifically responsible for preventing the entry of water and other substances. C: Stratum germinativum, also known as the stratum basale, is responsible for cell division and regeneration, not primarily for barrier function.