The keratinocytes are tightly connected with each other by

Correct Answer: B

Rationale: The correct answer is B: desmosomes. Desmosomes are specialized cell junctions that firmly attach keratinocytes together in the epidermis. Desmosomes provide mechanical strength and stability to the epidermis by forming strong connections between adjacent cells. Elastic fibers (choice A) provide elasticity to tissues but are not involved in cell-to-cell connections. Keratin (choice C) is a fibrous protein that forms the structural basis of keratinocytes but does not directly connect them. Prekeratin (choice D) is a precursor to keratin and is not involved in cell-cell adhesion.

Correct Answer: A

Rationale: The correct answer is A because epidermal ridges do not extend into the dermis. The ridges are formed by the epidermis and serve to increase friction for grasping objects. Choice B is correct as epidermal ridge patterns are genetically determined. Choice C is also correct as the ridges interconnect with dermal papillae for stability. Choice D is incorrect as epidermal ridges do contain increased numbers of free nerve endings, contributing to the sense of touch.

Correct Answer: A

Rationale: The correct answer is A: stratum basale. Melanosomes, which contain melanin pigment responsible for skin color, are produced and released by melanocytes in the stratum basale layer of the epidermis. Melanocytes transfer melanosomes to neighboring keratinocytes, providing protection against UV radiation. The other choices are incorrect because melanosomes are not released from the reticular layer of dermis (B), stratum corneum (C), or hypodermis (D). The stratum corneum is the outermost layer of the epidermis composed of dead skin cells, while the hypodermis is primarily involved in fat storage and insulation.

Correct Answer: B

Rationale: The correct answer is B: melanin. Melanin is the pigment responsible for determining the color of the skin, hair, and eyes. Albino individuals lack melanin production, leading to their characteristic lack of pigmentation. Perspiration (A), carotene (C), and hemoglobin (D) are not affected by albinism. Perspiration is produced by sweat glands, carotene is a pigment found in fruits and vegetables, and hemoglobin is a protein in red blood cells responsible for carrying oxygen.

Correct Answer: A

Rationale: The correct answer is A: dermatologist. A dermatologist is a physician who specializes in diagnosing and treating disorders of the skin. They undergo specific training in dermatology, making them experts in skin conditions. Sweat glands (B) are not physicians but structures in the skin. Keratosis (C) refers to a skin condition characterized by rough, scaly patches. Dysplastic Nevi (D) are atypical moles that may require monitoring by a dermatologist but do not specialize in treating skin disorders.