What is an organism with chloroplast in its cell?

Correct Answer: B

Rationale: Chloroplasts, organelles containing chlorophyll, enable organisms to perform photosynthesis, converting sunlight, carbon dioxide, and water into glucose. Organisms with chloroplasts, like plants and algae, are autotrophs, producing their own food. Heterotrophs, such as animals, consume others for energy, lacking chloroplasts. Herbivores eat plants but don't photosynthesize, and primary consumers occupy an ecological role, not a metabolic one. Autotrophs' self-sustaining capability, reliant on chloroplasts, sets them apart, aligning with their role as producers in ecosystems and their cellular structure.

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: D

Rationale: Thick filaments in sarcomeres are composed of myosin, with heads forming cross-bridges to pull actin during contraction, creating the A band's density. Troponin and tropomyosin, regulatory proteins, pair with actin in thin filaments, not thick. Actin forms thin filaments, overlapping myosin, not constituting thick ones. Myosin's exclusive role in thick filaments drives force generation, distinguishing it from thin filament components, fundamental to muscle contraction mechanics.

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.