Excretion is the removal of __________ from the body.

Correct Answer: C

Rationale: Excretion removes metabolic waste e.g., urea, COâ‚‚ from cellular processes (kidneys, lungs). Undigested food waste is defecation not excretion in this context. Used hormones are degraded not primarily excreted whole. Pathogens are fought by immunity not routinely excreted. Metabolic waste's removal distinguishes it, critical for homeostasis, unlike fecal, hormonal, or immune processes.

Correct Answer: C

Rationale: Lobule isn't a kidney region medulla, cortex, pelvis are (e.g., anatomical divisions). Medulla has pyramids inner. Cortex has nephrons outer. Pelvis collects urine central. Lobule is liver/brain term distinguishing it, critical for renal anatomy, unlike true regions.

Correct Answer: B

Rationale: Water returns from PCT by osmosis follows Na gradient (e.g., isosmotic reabsorption). Active transport moves Na not water directly. Facilitated diffusion is glucose not water. Carrier molecules aid solutes not primary water. Osmosis's passive flow distinguishes it, critical for PCT water recovery, unlike active or facilitated mechanisms.

Correct Answer: A

Rationale: Water reabsorption from Loop of Henle (descending) depends on NaCl movement out e.g., thick ascending pumps create gradient (~1200 mOsm). Acid is distal not Loop. Glucose is PCT not here. Uric acid is minor not gradient driver. NaCl's role distinguishes it, critical for countercurrent, unlike other solutes.

Correct Answer: A

Rationale: The JGA monitors blood volume senses pressure via JG cells (e.g., renin adjusts). Medulla oblongata controls breathing not volume. Midbrain is motor unrelated. Hypothalamus senses osmolarity not volume directly. JGA's volume role distinguishes it, key to RAAS, unlike neural or osmotic structures.