What is the largest muscle in the lower leg?

Correct Answer: B

Rationale: The gastrocnemius, a two-headed muscle overlying soleus, is the largest in the lower leg, spanning from femoral condyles to the Achilles tendon, driving plantarflexion (e.g., calf raises). Soleus , beneath it, is smaller but assists. Tibialis anterior dorsiflexes, and tibialis posterior inverts both are slimmer. Gastrocnemius's bulk and superficial prominence, critical for locomotion, make 'b' the correct answer.

Correct Answer: B

Rationale: Abduction moves limbs or fingers away from the midline, like spreading arms or fanning fingers, driven by muscles like deltoid or abductor digiti minimi. Adduction brings them toward the midline. Rotation twists around an axis. Extension straightens joints. Abduction's lateral movement, per anatomical planes, makes 'b' the correct action.

Correct Answer: A

Rationale: A tissue is a group of similar cells with a common function, like muscle or epithelial tissue, forming the basic structural units between individual cells and organs in the body's hierarchy. A type of organ is incorrect organs comprise multiple tissues (e.g., skin includes epithelium and connective tissue). A fluid might describe blood, a tissue, but not all tissues are fluids (e.g., bone). A structural protein like collagen exists within tissues, not as tissue itself. The definition of tissue as cellular aggregates with shared roles, per histology, makes 'a' the correct answer.

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: D

Rationale: The skeletal system's primary functions include all: hormone production (e.g., osteocalcin from osteoblasts), blood cell production (marrow in long bones), and protection/support (e.g., skull, rib cage), a comprehensive role. No single function excludes others bones multitask. This broad scope, per skeletal physiology, makes 'd' correct.