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Rationales 2026 Q&A | Instant Download Pdf
1.
A 54-year-old man presents with crushing substernal chest pain
radiating to the left arm. ECG shows ST elevation in leads II, III, and aVF.
Which coronary artery is most likely occluded?
A. Left anterior descending artery
B. Left circumflex artery
C. Right coronary artery
D. Posterior descending artery
Answer: C. Right coronary artery
Inferior wall myocardial infarction is classically associated with
occlusion of the right coronary artery, which supplies leads II, III, and
aVF in most individuals.
2.
,A 23-year-old woman presents with tremor, heat intolerance, and
weight loss. Lab studies show decreased TSH and elevated free T4.
Which antibody is most likely present?
A. Anti-thyroid peroxidase
B. Anti-TSH receptor
C. Anti-thyroglobulin
D. Anti-microsomal antibody
Answer: B. Anti-TSH receptor
Graves disease is caused by thyroid-stimulating immunoglobulins that
activate the TSH receptor, leading to hyperthyroidism.
3.
Which structure is the primary site of gas exchange in the lungs?
A. Terminal bronchioles
B. Respiratory bronchioles
C. Alveoli
D. Alveolar ducts
Answer: C. Alveoli
Alveoli provide the large surface area and thin diffusion barrier
necessary for efficient oxygen and carbon dioxide exchange.
,4.
A patient with cirrhosis develops confusion and asterixis. Which
substance most directly contributes to his symptoms?
A. Bilirubin
B. Ammonia
C. Urea
D. Lactate
Answer: B. Ammonia
Hepatic failure leads to impaired ammonia metabolism, causing
elevated ammonia levels and hepatic encephalopathy.
5.
Which vitamin deficiency is associated with scurvy?
A. Vitamin A
B. Vitamin B1
C. Vitamin C
D. Vitamin D
, Answer: C. Vitamin C
Vitamin C is required for collagen synthesis; deficiency leads to
defective connective tissue and bleeding gums.
6.
A 65-year-old man has difficulty initiating urination and a weak urinary
stream. Which prostate zone is most likely enlarged?
A. Peripheral zone
B. Central zone
C. Transitional zone
D. Anterior fibromuscular stroma
Answer: C. Transitional zone
Benign prostatic hyperplasia arises from the transitional zone,
compressing the urethra and causing obstructive urinary symptoms.
7.
Which neurotransmitter is primarily involved in reward pathways in the
brain?
A. Serotonin
B. Dopamine