The 'prickle-cell layer' of the skin is -

Correct Answer: A

Rationale: The correct answer is A: Stratum spinosum. The prickle-cell layer is another name for the stratum spinosum. This layer is located between the stratum basale and stratum granulosum in the epidermis. It consists of cells that appear spiny under a microscope due to desmosomes between them. These desmosomes give the cells a prickle-like appearance. The stratum corneum (B) is the outermost layer of the epidermis, composed of dead keratinocytes. The stratum germinativum (C) is another name for the stratum basale, the deepest layer of the epidermis where cell division occurs. Choice D is incorrect as the prickle-cell layer does have a specific name, which is the stratum spinosum.

Correct Answer: A

Rationale: The correct answer is A: Rhinoceros. Rhinoceros is the only animal among the options that has sweat glands only on its pinnae (ears). The other choices, Deer, Hippopotamus, and Rabbit, have sweat glands distributed throughout their bodies or in different areas, not just on the pinnae. This unique anatomical feature of the Rhinoceros helps it regulate body temperature by cooling the blood vessels around the ears. Therefore, Rhinoceros is the correct answer based on the specific location of its sweat glands.

Correct Answer: D

Rationale: The correct answer is D: Stratum corneum. This layer of skin is water-proof due to the presence of keratin, a protein that forms a protective barrier against water loss and external substances. The other choices, A, B, and C, do not have the same water-proofing properties. Stratum germinativum is the innermost layer responsible for cell division, stratum granulosum is involved in keratin production, and stratum lucidum is a thin, translucent layer found only in thick skin areas. Therefore, only the stratum corneum contains the necessary structures to make it water-proof, making it the correct choice.

Correct Answer: C

Rationale: The correct answer is C because the dermis is the layer of skin that provides strength, flexibility, and elasticity, making it suitable for shoe leather. Choice A is incorrect because the presence of cells alone doesn't determine leather quality. Choice B is incorrect as hardness is not a desirable quality for shoe leather. Choice D is incorrect as ecdysis refers to the shedding of skin by animals, not the process of obtaining leather.

Correct Answer: A

Rationale: The correct answer is A: Arrector muscles. Arrector muscles are responsible for pulling the hair follicles and hairs upright when the temperature is low, a response known as piloerection. This physiological response helps to trap heat and maintain body temperature. Abductor muscles (Choice B) are not involved in hair erection. Petrihydroid muscles (Choice C) and Contractor muscles (Choice D) are not anatomical terms related to hair erection.