Which gland has an opening into hair follicle

Correct Answer: B

Rationale: The correct answer is B: Sebaceous gland. This gland produces sebum, an oily substance that lubricates the skin and hair. It opens into the hair follicle to distribute sebum along the hair shaft. Sweat glands (choice A) release sweat onto the skin surface, not into hair follicles. Perineal glands (choice C) are located in the genital area and do not open into hair follicles. Zeis glands (choice D) are associated with eyelash follicles, not hair follicles in general. Therefore, the sebaceous gland is the only gland among the choices that opens into hair follicles.

Correct Answer: A

Rationale: The correct answer is A: Skin. Vitamin D is synthesized in the skin when it is exposed to sunlight. UV rays convert a form of cholesterol in the skin into Vitamin D. The liver and kidney play roles in converting and activating Vitamin D, but they are not where Vitamin D is initially synthesized. The stomach is not involved in the synthesis of Vitamin D. So, the skin is the correct choice for the synthesis of Vitamin D in the presence of sunlight.

Correct Answer: C

Rationale: The correct answer is C: Conjunctiva. The conjunctiva is a thin, transparent mucous membrane that covers the front surface of the eye and lines the inside of the eyelids. It is the thinnest epidermis as it is only one cell thick, allowing for transparency and protection of the eye. The face, nipples, and lips have thicker epidermis layers compared to the conjunctiva, making them incorrect choices. Thus, the conjunctiva is the correct answer due to its unique thin structure and location.

Correct Answer: D

Rationale: Keratin found in rabbit skin is classified as a scleroprotein, which is a type of structural protein. Keratin is known for its tough and fibrous nature, providing strength and protection to the skin. Scleroproteins are characterized by their high tensile strength and are commonly found in structural tissues like skin, hair, and nails. Lipoproteins consist of lipids and proteins, glycoproteins have carbohydrate groups attached to the protein, and mucoproteins contain mucopolysaccharides. These types of proteins do not accurately describe the composition and function of keratin in rabbit skin.

Correct Answer: A

Rationale: Rationale: 1. Metachrosis refers to the ability of amphibians to change the intensity of their skin color. 2. Amphibians use metachrosis for camouflage, communication, and temperature regulation. 3. This process is not about shedding skin (B), thermoregulation (C), or metamorphosis (D). Summary of Incorrect Choices: B: Incorrect as metachrosis is about changing skin color, not shedding stratum corneum. C: Incorrect as metachrosis is not directly related to thermoregulation. D: Incorrect as metachrosis does not involve the transformation from larva to adult, which is metamorphosis.