Which layer of the skin is primarily responsible for producing new skin cells?

Correct Answer: C

Rationale: The stratum basale, the deepest epidermal layer, produces new skin cells via mitosis of basal keratinocytes, regenerating the epidermis as cells move upward. Stratum corneum is dead, keratinized cells. Stratum granulosum is for keratinization, not division. Stratum spinosum strengthens, not generates. The basale's role as the proliferative base, per skin histology, makes 'c' correct.

Correct Answer: B

Rationale: The axial skeleton includes the skull, vertebral column, and rib cage, forming the body's central axis for support/protection. Appendicular is limbs/girdles. Pectoral and pelvic girdles are appendicular parts. Axial's midline role, per skeletal division, makes 'b' correct.

Correct Answer: B

Rationale: The hyoid bone, free-floating in the neck, anchors tongue and larynx muscles (e.g., genioglossus), aiding speech/swallowing. It doesn't support the skull , protect thorax , or form skull base (d, occipital). Its muscular role, per anatomy, makes 'b' correct.

Correct Answer: D

Rationale: Paranasal sinuses (frontal, maxillary, etc.) warm/humidify air , produce mucus to trap debris, and lighten the skull (not a, reducing weight). All functions apply, enhancing respiration and skull structure, making 'd' correct.

Correct Answer: D

Rationale: Metabolism is the sum of all chemical reactions in an organism, including catabolism (breaking down) and anabolism (building up), powering life processes like growth. Adjustment to changes is homeostasis, not metabolism. Cell specialization is differentiation, new cell formation is regeneration distinct processes. Metabolism's comprehensive chemical scope, per physiology, makes 'd' correct.