Which muscle has a convergent pattern of fascicles?

Correct Answer: C

Rationale: Pectoralis major has a convergent fascicle pattern, with fibers fanning from a broad origin (clavicle, sternum) to a narrow insertion (humerus), enhancing force for arm adduction and rotation. Biceps brachii has parallel fascicles along its length for elbow flexion. Gluteus maximus features multipennate fibers for hip extension. Rectus femoris runs parallel for knee extension. Convergent patterns concentrate force from multiple directions, distinguishing pectoralis major's structure and function, key for chest movements, unlike parallel or pennate arrangements.

Correct Answer: B

Rationale: Vastus intermedius, a quadriceps muscle, lies deep to rectus femoris, which overlays it on the anterior thigh, both extending the knee. Biceps femoris, a hamstring, is posterior. Vastus medialis and lateralis flank it laterally and medially, not superiorly. Rectus femoris' superficial position distinguishes it, key for quadriceps layering.

Correct Answer: D

Rationale: Water's ability to mound above a glass rim results from surface tension, a property arising from cohesive forces between its molecules. Hydrogen bonds create a strong, elastic 'skin' at the surface, resisting external disruption and allowing water to hold together against gravity briefly. Specific gravity relates to density, not this behavior. Cohesion contributes but isn't the complete mechanism. Opacity, transparency-related, is irrelevant. Surface tension's role in forming this temporary barrier, driven by molecular attraction, explains the phenomenon, a key feature in water's physical behavior.

Correct Answer: C

Rationale: Acidity depends on ion concentration affecting pH. Hydronium ions (H₃O⁺), formed when protons (H⁺) bond with water, increase in acidic solutions, lowering pH below 7, as in vinegar. Hydroxyl ions (OH⁻) raise pH, making solutions basic. Sodium and potassium ions, from salts, are neutral, minimally shifting pH unless paired with strong acids or bases. Hydronium's direct link to proton donation defines acidity, distinguishing it in chemical equilibria and pH measurement.

Correct Answer: A

Rationale: The kidney filters blood and regulates fluid balance primarily through nephrons microscopic units numbering millions per kidney. Each nephron's glomerulus filters plasma, while tubules reabsorb water, glucose, and ions, and excrete waste as urine. Neurons conduct signals, ureters transport urine, and alveoli exchange lung gases. The nephron's integrated filtration, reabsorption, and secretion, occurring in structures like the loop of Henle, perform the kidney's core work, maintaining homeostasis and distinguishing it as the functional powerhouse.