The hair follicles in dermis are attached with-

Correct Answer: A

Rationale: The correct answer is A: Unstriped arrector pili muscles. These muscles are attached to the hair follicles in the dermis. They contract in response to stimuli like cold or fear, causing the hair to stand up (goosebumps). Choice B, "Goose flesh," is a sensory response caused by the contraction of arrector pili muscles, not the attachment itself. Choices C and D, Vibrissae and Panniculus adiposus, are not directly involved in the attachment of hair follicles in the dermis.

Correct Answer: D

Rationale: The correct answer is D: Stratum corneum of the skin. Nails, claws, horns, and hooves in mammals are produced by keratinized structures in the epidermis called the stratum corneum. This specialized layer of the skin is responsible for forming these protective structures. Cartilage (A) is not involved in the production of these structures. Bone (B) is part of the skeletal system and not directly responsible for the formation of nails, claws, horns, or hooves. Muscles of the skin (C) are involved in movement and expression but do not produce these particular structures. Therefore, the correct answer is D as it directly relates to the formation of nails, claws, horns, and hooves in mammals.

Correct Answer: D

Rationale: The correct answer is D because in mammals, scent glands can be modified sudorific (sweat) glands and sebaceous (oil) glands. Sudorific glands produce sweat that can carry scent, while sebaceous glands secrete oily substances that can also contribute to scent communication. Mucous glands, as mentioned in option C, are not typically involved in scent production in mammals. Option A and B individually are not comprehensive enough to cover all types of scent gland modifications found in mammals. Thus, the correct answer is D as it includes both sudorific and sebaceous glands, which are commonly modified for scent production in mammals.

Correct Answer: B

Rationale: The correct answer is B: Stratum lucidum. Eleidin is a protein-rich substance found in the stratum lucidum, the clear layer of the epidermis located between the stratum corneum and stratum granulosum. This layer is characterized by its translucent appearance due to the presence of eleidin, which helps to provide waterproofing and protection to the skin. The stratum germinativum (A) is responsible for cell proliferation, the stratum granulosum (C) is where keratinocytes undergo apoptosis, and the stratum corneum (D) consists of dead keratinocytes and serves as a barrier to external factors.

Correct Answer: A

Rationale: The correct answer is A: 5. The thorn penetrated through the sole of Joe's foot to the dermis. The epidermis has 5 layers: stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. As the thorn reached the dermis, it had to pass through all 5 layers of the epidermis. Therefore, the correct answer is 5. Summary: B: 2 - Incorrect, not enough layers penetrated. C: 0 - Incorrect, the thorn penetrated the epidermis. D: 4 - Incorrect, the thorn penetrated all 5 layers of the epidermis.