If Tmax for a certain nephron was 200 and blood glucose was 200 mg/ml with normal GFR (125ml/min) the excreted glucose equals?

Correct Answer: C

Rationale: First, convert blood glucose: 200 mg/ml = 20,000 mg/dl. Glucose filtration rate = blood glucose × GFR = 20,000 mg/dl × 1.25 dl/min = 25,000 mg/min. Tmax (reabsorption limit) is 200 mg/min. Excreted glucose = filtered - Tmax = 25,000 - 200 = 24,800 mg/min. However, the explanation suggests 250 mg/min filtered (likely 200 mg/dl intended), yielding 50 mg/min excreted (250 - 200), aligning with C.

Correct Answer: C

Rationale: Chemical buffer systems neutralize H⁺ instantly: phosphate (HPO₄²⁻/H₂PO₄⁻), bicarbonate (HCO₃⁻/H₂CO₃), and proteins (e.g., hemoglobin). The respiratory system (C) regulates CO₂ via ventilation, a physiological mechanism, not a chemical buffer, acting over minutes, not instantly, making C the exception.

Correct Answer: B

Rationale: Middle age (roughly 40-65) involves reevaluating life, often rediscovering satisfaction in relationships (B), per Erikson's generativity vs. stagnation stage, focusing on legacy and connection. Learning (A) is earlier, spirituality (C) varies, and risk-taking (D) is more adolescent, making B the primary task.

Correct Answer: B

Rationale: Adolescents (B) face peer pressure and busy schedules (e.g., school, sports), delaying voiding and risking habits like holding urine. Infants/toddlers (A) lack control, middle-aged adults (C) focus on work/health, and older adults (D) face physical issues, making B the group affected by these social factors.

Correct Answer: D

Rationale: Urea enters via filtrate (A), concentrates in cortical collecting ducts as water exits (B), and thin loops/medullary ducts allow urea recycling (C). All are true—filtrate supplies urea, water reabsorption concentrates it, permeable segments recycle it—making E (all are correct), reassigned as D, correct.