The elimination of substances from the body in the urine is called:

Correct Answer: C

Rationale: Urine excretion is the elimination of substances via urine final output (e.g., waste removal). Secretion adds to urine specific process. Reabsorption conserves opposite. Filtration starts not eliminates. Excretion's end role distinguishes it, key to renal clearance, unlike process-specific terms.

Correct Answer: C

Rationale: Peptides are reabsorbed via endocytosis PCT engulfs small proteins (e.g., filtered peptides), energy-dependent. Facilitated diffusion suits glucose not peptides. Active transport is Na not engulfing. Passive diffusion lacks mechanism insufficient. Endocytosis distinguishes it, critical for protein recovery, unlike diffusion or pump methods.

Correct Answer: B

Rationale: The thin descending limb is water-permeable, ion-impermeable osmosis concentrates filtrate (e.g., countercurrent). PCT is leaky ions/water pass. Cortical collecting duct adjusts with ADH ions move. Thick ascending pumps ions water-impermeable. Unique permeability distinguishes thin descending, critical for gradient, unlike leaky or adjustable segments.

Correct Answer: C

Rationale: ADH won't stop diuresis in nephrogenic diabetes insipidus tubules resist (e.g., receptor defect). Lack of ADH responds diabetes insipidus. Excess water dilutes ADH corrects. Combined is treatable ADH works. Resistance distinguishes it, critical for ADH failure, unlike responsive causes.

Correct Answer: B

Rationale: Low [H₂CO₃] is difficult to measure rapidly dissociates to CO₂/H₂O (e.g., lab challenge). Easy estimation misstates requires CO₂ proxy. Ineffective ignores Henderson-Hasselbalch false. Replacement isn't needed CO₂ suffices. Measurement difficulty distinguishes it, critical for pH calculation, unlike estimation or equation errors.