Metabolic acidosis occurs in the oliguric phase of acute renal failure as a result of impaired

Correct Answer: A

Rationale: In oliguric acute renal failure, impaired ammonia synthesis prevents hydrogen ion buffering, causing acidosis not sodium excretion (electrolyte), bicarbonate loss (compensatory), or potassium retention (separate issue). This distinguishes renal acidosis etiology, critical for managing pH imbalance, contrasting with electrolyte-focused mechanisms.

Correct Answer: B

Rationale: Acute rejection presents with fever and graft tenderness from immune attack not tachycardia (nonspecific), hypotension (shock), or infections (complications). This distinguishes acute rejection signs, critical for patient education, contrasting with systemic or infectious issues.

Correct Answer: B

Rationale: UTIs are common in women, less so in older men, and occur in community/hospital settings, but E. coli (not Streptococcus pyogenes) is the commonest cause (>80%). This exception distinguishes UTI microbiology, vital for treatment, contrasting with streptococcal dominance.

Correct Answer: D

Rationale: Lesch-Nyhan syndrome results from HGPRT deficiency, impairing purine salvage, raising uric acid not pyrimidine pathways or xanthine oxidase. This distinguishes purine metabolism defects, critical for neurologic/renal symptoms, contrasting with other enzymes.

Correct Answer: D

Rationale: Podocytes have processes, filaments, and form the filtration barrier not part of the juxtaglomerular apparatus (macula densa, JG cells). This distinguishes podocyte function, critical for filtration, contrasting with JGA regulation.