Substance secreted by sebaceous gland is called -

Correct Answer: D

Rationale: The correct answer is D: Sebum. Sebum is the substance secreted by the sebaceous glands in the skin. Sebum helps to lubricate and waterproof the skin and hair. Cerumin (A) is the substance produced by ceruminous glands in the ear canal. Sweat (B) is produced by sweat glands to regulate body temperature. Mucous (C) is produced by mucous glands to protect and lubricate the mucous membranes. Therefore, the correct answer is D as it specifically refers to the substance secreted by the sebaceous glands.

Correct Answer: D

Rationale: The correct answer is D because the folder upper part of the dermis is composed of both skin papilla and hair papilla. Skin papilla plays a role in nourishing the epidermis, while hair papilla supports hair growth. Choice A, skin papilla only, is incorrect as it does not account for the hair papilla's presence. Choice B, hair papilla only, is also incorrect as it neglects the role of the skin papilla. Choice C, dermal papilla only, is incorrect as it does not specify the individual components involved in the upper part of the dermis. Thus, the correct answer is D, which accurately reflects the presence of both skin papilla and hair papilla in the folder upper part of the dermis.

Correct Answer: B

Rationale: Step 1: Arrector pili muscles are responsible for hair erection. Step 2: Sympathetic nervous system controls arrector pili muscles. Step 3: Adrenaline is released in response to stress, cold, heat, or anger. Step 4: Adrenaline activates sympathetic nervous system. Step 5: Sympathetic stimulation causes contraction of arrector pili muscles, leading to hair erection. Therefore, the correct answer is B: Adrenaline and sympathetic stimulation. Summary: - A: Adrenaline alone is not sufficient as it needs to activate the sympathetic nervous system. - C: Sympathetic stimulation alone does not explain the role of adrenaline. - D: Calcitiotinin is not involved in the contraction of arrector pili muscles.

Correct Answer: D

Rationale: The correct answer is D because the integument of a rabbit serves multiple functions. It conserves heat in winter by providing insulation, loses excess heat during summer through mechanisms like vasodilation, and regulates body temperature by adjusting blood flow and fur density. Choice A is correct but incomplete, as the integument also helps in thermoregulation. Choice B is incorrect as the integument helps in both heat conservation and dissipation. Choice C is also incorrect as the integument does more than just regulating body temperature, such as protecting against external factors and providing sensory functions.

Correct Answer: B

Rationale: The correct answer is B: Keratin. Keratin is a fibrous structural protein found in the horns, nails, hairs, and feathers of birds. It provides strength and flexibility to these structures. Collagen (A) is a different protein found in connective tissues. Mucin (C) is a glycoprotein found in mucus. Cuticle (D) is a protective outer layer found in plants and insects, not in the mentioned structures. Therefore, based on the composition and function of horns, nails, hairs, and feathers, keratin is the most appropriate choice.