A closed container of hydrogen gas is warmed from 20°C to 25°C. If the volume remains the same, what will happen to the pressure in the container?

Correct Answer: D

Rationale: In a closed container with fixed volume, Gay-Lussac's law states pressure rises with temperature. Warming hydrogen from 20°C to 25°C increases molecular kinetic energy, causing more frequent, forceful collisions with container walls. Pressure, the force per area, thus increases proportionally (P ∝ T in Kelvin: 293K to 298K). It doesn't stay constant, decrease, or fluctuate without volume change. This pressure rise, a gas law fundamental, reflects temperature's direct impact on confined gas behavior.

Correct Answer: C

Rationale: Muscle names often reflect origin (fixed attachment) and insertion (movable end). Sternocleidomastoid specifies origins on the sternum and clavicle, inserting on the mastoid process of the temporal bone, guiding neck movement. Transversus abdominus denotes fibre direction and location, semimembranosus' implies membrane-like shape and location, and deltoid reflects its triangular shape. Only sternocleidomastoid explicitly ties to origin-insertion points, a naming style aiding anatomical precision, distinguishing it from shape-, action-, or location-based names in functional mapping.

Correct Answer: B

Rationale: Within myofibrils, sarcomeres are the contractile units, shortening as actin and myosin slide past each other, powered by ATP. Sarcoplasm is cytoplasm, sarcolemma the membrane, and sarcoplasmic reticulum a calcium store not contractile. Sarcomeres' banded structure, from Z-line to Z-line, enables muscle contraction, their collective action summing to fibre shortening, distinguishing them as the functional core of myofibril mechanics in muscle physiology.

Correct Answer: B

Rationale: Skeletal muscle exhibits excitability (signal response), contractility (shortening), and extensibility (stretching), but is innervated by the somatic nervous system for voluntary control, not the autonomic system, which governs involuntary smooth and cardiac muscles. This voluntary innervation distinguishes skeletal muscle's conscious movement role e.g., lifting from autonomic-regulated visceral functions, key to its physiological classification.

Correct Answer: A

Rationale: A sarcomere, a myofibril segment between Z-lines (2 micrometres), is smaller than myofibrils (cell-length), muscle fibres (cells), and fasciculi (fibre bundles). Containing myofilaments, it's the basic contractile unit, distinguishing it as the smallest listed structure, foundational to muscle shortening and force generation.