Sudorific glands are confined to external ears in

Correct Answer: C

Rationale: The correct answer is C: Hippopotamus. Sudorific glands are sweat glands responsible for regulating body temperature. Hippopotamuses have sudorific glands confined to their external ears, which help them cool down. Deer and kangaroos do not have sudorific glands in their external ears. Choice D, "Acting as receptor organ," is vague and unrelated to the function of sudorific glands.

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: C

Rationale: Rationale: Taxidermy involves preserving the whole skin (epidermis and dermis) using chemicals to maintain the lifelike appearance of an animal. Albinism is a genetic condition causing lack of pigmentation. Toxicology is the study of the adverse effects of chemicals on living organisms. Tanning is a process of treating animal hides to produce leather, not preserving the whole skin.

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.