The structural and functional unit of the kidney is the

Correct Answer: B

Rationale: The nephron is the kidney's structural and functional unit, filtering blood and forming urine. 'Nephron,' is correct, per physiology texts like Vander, encompassing glomerulus and tubules. 'Glomerulus,' is part of the nephron. 'Renal artery,' supplies blood. 'Bowman's capsule,' encases the glomerulus within the nephron. The nephron's comprehensive role in filtration, reabsorption, and excretion makes B the precise answer.

Correct Answer: C

Rationale: The peripheral nervous system (PNS) includes nerves outside the CNS. 'Spinal cord,' is correct as the exception, part of the CNS, per anatomy (e.g., Tortora). 'Cranial nerves,' and 'Spinal nerves,' are PNS. 'Autonomic nervous system,' is PNS's involuntary arm. Spinal cord's CNS role makes C the accurate answer.

Correct Answer: B

Rationale: The diaphragm is the primary muscle dividing thoracic and abdominal cavities, aiding respiration. 'Diaphragm,' is correct, per anatomy (e.g., Moore). 'Intercostal,' assists breathing between ribs. 'Rectus abdominis,' is abdominal. 'Pectoralis major,' is chest. Diaphragm's septal role makes B the accurate answer.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: D

Rationale: Bacterial toxins harm hosts. 'Hemolysin,' is correct as the exception, an effect (lysing blood cells), not a toxin class, per microbiology (e.g., Tortora). 'Endotoxin,' is LPS from gram-negative bacteria. 'Exotoxin,' is secreted protein. 'Neurotoxin,' targets nerves. Hemolysin's specificity makes D the precise answer.