Use of oxygen to breakdown the food for the formation of energy is

Correct Answer: C

Rationale: Cellular respiration encompasses breaking down food (glucose) with oxygen to produce energy (ATP) in cells, mainly via aerobic means in mitochondria, releasing carbon dioxide and water. Anaerobic respiration skips oxygen, yielding less energy and lactic acid. Aerobic respiration is a subset, but cellular respiration covers all energy-making processes, fitting broadly. Oxygen is a reactant, not the process. This oxygen-dependent breakdown fuels most organisms, contrasting anaerobic's limited scope, and its cellular scope includes glycolysis and beyond, making it the precise term for energy formation across living systems.

Correct Answer: D

Rationale: When ADP and inorganic phosphate (P) release from myosin's head after ATP hydrolysis, the cross-bridge bends, pulling actin toward the sarcomere's center the power stroke. This single event encompasses bridge bending, filament pulling, and the stroke itself, driving contraction. Each aspect isn't separate; they're facets of one action. Bending alone omits the pull, pulling alone skips mechanics, and power-stroke alone undersells the full process. All occur simultaneously as myosin resets, distinguishing this step from prior ATP binding or later detachment, critical for the sliding filament cycle and muscle shortening.

Correct Answer: A

Rationale: Antagonists are muscles with opposing actions, like biceps flexing the elbow and triceps extending it, ensuring balanced movement and control. Agonists (prime movers) drive the main action, contracting together. Synergists assist agonists, stabilizing or refining motion. Prime movers overlap with agonists, not opposites. Antagonists' counteraction is unique, relaxing when agonists contract, distinct from cooperative or leading roles, essential for coordinated, reversible motion in the musculoskeletal system.

Correct Answer: B

Rationale: External intercostals lift ribs during inspiration, expanding the chest for inhalation. Internal intercostals depress ribs in forced expiration, aiding exhalation. Opposite pairing misaligns their roles. Trunk flexion or extension involves abdominals or back muscles, not intercostals. Their respiratory functions distinguish them, critical for breathing mechanics, unlike trunk movement roles.

Correct Answer: B

Rationale: Medial thigh muscles, like adductor longus, pull the thigh toward the midline, adducting it, as in crossing legs. Abduction moves it outward, a lateral thigh role. Leg extension (knee) or flexion involves quadriceps or hamstrings, not medial focus. Adduction defines their action, distinct from lateral, knee, or bending functions, key for thigh stability.