Which of the following is NOT a nitrogenous waste excreted by the kidneys?

Correct Answer: A

Rationale: Amino acids aren't nitrogenous wastes reabsorbed or metabolized, not excreted (e.g., PCT). Urea, from protein breakdown major waste. Uric acid, from purines excreted. Creatinine, from muscle waste product. Amino acids' conservation distinguishes them, critical for nitrogen reuse, unlike waste products excreted.

Correct Answer: A

Rationale: Glomeruli are in the cortex cortical nephrons dominate (e.g., filtration zone). Medulla has fewer juxtamedullary. Pelvis collects not filters. Pyramids are medullary subset. Cortex's glomerular density distinguishes it, critical for GFR, unlike deeper or collecting areas.

Correct Answer: A

Rationale: Blood flows: afferent arteriole, glomerulus, efferent arteriole, peritubular capillary e.g., filtration to reabsorption. Peritubular before glomerulus reverses impossible. Efferent first skips input wrong. Peritubular start ignores filtration false. Correct order distinguishes it, key to nephron circulation, unlike reversed sequences.

Correct Answer: B

Rationale: Urea adds to medullary solute concentration recycles in collecting duct (e.g., ~1200 mOsm with NaCl). Sugar is reabsorbed not medullary. Proteins are filtered out not concentrated. Bicarbonate is pH-related not osmotic. Urea's contribution distinguishes it, key to concentration gradient, unlike filtered or pH solutes.

Correct Answer: B

Rationale: Alcohol is a diuretic inhibits ADH secretion (e.g., hypothalamus suppression), increasing urine. Antidiuretic increases retention opposite. Diuretic/increases ADH contradicts more water retained. Antidiuretic/inhibits misnames diuresis occurs. Diuretic/inhibition distinguishes it, key to alcohol's effect, unlike retention or reverse errors.