Which is moved the least during muscle contraction?

Correct Answer: A

Rationale: The origin, a muscle's fixed attachment (e.g., biceps on scapula), moves least during contraction, anchoring the muscle as it pulls the insertion (e.g., radius) toward it. The insertion moves most, effecting motion. Ligaments, stabilizing joints, don't move but stretch minimally. Joints shift position via bone movement, more than the origin. The origin's stability provides leverage, distinguishing it as the least mobile, critical for force transmission, unlike the dynamic insertion, passive ligaments, or pivoting joints in muscle action.

Correct Answer: B

Rationale: Gastrocnemius, spanning the calf, is the largest lower leg muscle, plantarflexing the foot with two heads. Soleus, beneath it, assists but is smaller. Tibialis anterior dorsiflexes, smaller and anterior. Tibialis posterior supports the arch, not largest. Gastrocnemius' bulk and power distinguish it, key for walking and jumping.

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: C

Rationale: Work in physics is force times distance. Both lifted identical chairs the same vertical distance, applying equal force against gravity (the chair's weight). Age or strength doesn't alter the chair's mass or height moved, so work done is identical. Without data on differing distances or forces like lifting speed or extra effort both perform equal work. This reflects work's definition, focusing on displacement and force, not individual capacity, making their efforts mechanically equivalent.

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.