1. Vitamin A deficiency causes what symptom?
Answer: Night blindness
Explanation: Vitamin A is required for rhodopsin in photoreceptors.
2. Which enzyme converts glucose → glucose-6-phosphate in most tissues?
Answer: Hexokinase
Explanation: Hexokinase has low Km and works in most cells.
3. What type of hypersensitivity is anaphylaxis?
Answer: Type I
Explanation: IgE-mediated mast-cell degranulation.
4. Which immunoglobulin is most abundant in blood?
Answer: IgG
Explanation: IgG is the dominant serum antibody.
5. Main excitatory neurotransmitter in CNS?
Answer: Glutamate
Explanation: It binds NMDA/AMPA receptors to depolarize neurons.
6. What produces cerebrospinal fluid?
Answer: Choroid plexus
Explanation: Specialized ependymal cells secrete CSF.
7. Zona glomerulosa produces which hormone?
Answer: Aldosterone
Explanation: First adrenal cortex layer, part of RAAS.
8. Enzyme deficient in albinism?
Answer: Tyrosinase
Explanation: Needed to convert tyrosine → melanin.
9. Bacteria linked to rheumatic fever?
Answer: Group A Streptococcus
Explanation: M-protein molecular mimicry triggers autoimmunity.
10. Most common cause of community pneumonia?
Answer: Streptococcus pneumoniae
Explanation: Gram-positive diplococcus; lobar pneumonia.
11. Artery torn in epidural hematoma?
Answer: Middle meningeal artery
Explanation: Trauma fractures temporal bone → arterial bleed.
12. Mutation of CFTR causes what disease?
Answer: Cystic fibrosis
Explanation: Impaired chloride transport → thick mucus.
13. Name a vitamin K–dependent clotting factor.
Answer: II, VII, IX, or X
Explanation: Vitamin K needed for gamma-carboxylation.
14. Antidote for acetaminophen overdose?
Answer: N-acetylcysteine
Explanation: Replenishes glutathione to detox NAPQI.
15. Organelle for protein synthesis?
Answer: Ribosome
Explanation: Translates mRNA into proteins.
16. Nerve to the deltoid?
Answer: Axillary nerve
Explanation: Injury occurs with surgical neck humerus fractures.
17. Organism causing Lyme disease?
Answer: Borrelia burgdorferi
Explanation: Spirochete transmitted by Ixodes tick.
18. Hormone increasing serum Ca²⁺?
Answer: PTH
Explanation: Increases bone resorption, kidney Ca²⁺ reabsorption.
19. Function of lung surfactant?
Answer: Decrease surface tension
Explanation: Prevents alveolar collapse.
20. Cells that produce insulin?
Answer: Pancreatic beta cells
Explanation: Located in islets of Langerhans.
21. Cause of tuberculosis?
Answer: Mycobacterium tuberculosis
Explanation: Acid-fast bacillus; caseating granulomas.
22. Main inhibitory neurotransmitter in CNS?
Answer: GABA
Explanation: Opens Cl⁻ channels to hyperpolarize neurons.
23. Vitamin deficient in pernicious anemia?
Answer: Vitamin B12
Explanation: Autoimmune loss of intrinsic factor.
24. Dermatome at nipple line?
Answer: T4
Explanation: Classic high-yield dermatome landmark.
25. Primary function of Golgi apparatus?
Answer: Protein modification and packaging
Explanation: Glycosylates and sorts proteins.
26. Bacteria causing whooping cough?
Answer: Bordetella pertussis
Explanation: Toxin increases cAMP → severe coughing.
27. Destruction of substantia nigra causes what disease?
Answer: Parkinson disease
Explanation: Loss of dopamine → bradykinesia, tremor.
28. Antibiotics that irreversibly inhibit bacterial ribosomes?
Answer: Aminoglycosides
Explanation: Bind 30S subunit; bactericidal.
29. Virus most often causing mononucleosis?
Answer: EBV
Explanation: Infects B cells via CD21.
30. Most common primary brain tumor in adults?
Answer: Glioblastoma multiforme
Explanation: Highly malignant, crosses corpus callosum.
31. Organ affected in Hashimoto disease?
Answer: Thyroid
Explanation: Autoimmune destruction → hypothyroidism.
32. Deficiency of dopamine in the basal ganglia causes what?
Answer: Parkinson disease
Explanation: Loss of substantia nigra pars compacta.
33. What virus causes chickenpox?
Answer: Varicella-zoster virus
Explanation: Later reactivates as shingles.
34. Genetic trisomy causing intellectual disability with flat facies?
Answer: Down syndrome (Trisomy 21)
Explanation: Meiotic nondisjunction most common cause.
35. What type of necrosis occurs in the pancreas?
Answer: Fat necrosis
Explanation: Lipase release → saponification.
36. Antidote for benzodiazepine overdose?
Answer: Flumazenil
Explanation: Competitive GABA-A receptor antagonist.
37. What is the oxygen-carrying protein in muscle?
Answer: Myoglobin
Explanation: Stores O₂ in muscle tissue.
38. Which artery supplies the AV node?
Answer: Right coronary artery (usually)
Explanation: Dominance determines supply.
39. Which cell type presents antigens via MHC II?
Answer: Dendritic cells
Explanation: Professional APCs for CD4+ T cells.
40. What is the main cause of diabetic ketoacidosis?
Answer: Insulin deficiency
Explanation: Leads to lipolysis → ketone formation.
41. Major inhibitory neurotransmitter in spinal cord?
Answer: Glycine
Explanation: Hyperpolarizes motor neurons.
42. First-line treatment for anaphylaxis?
Answer: Epinephrine
Explanation: Alpha and beta effects reverse hypotension & bronchospasm.
43. Site of RBC destruction?
Answer: Spleen
Explanation: Macrophages remove aged or damaged RBCs.
44. Hormone elevated in acromegaly?
Answer: Growth hormone
Explanation: Usually from pituitary adenoma.
45. Primary cause of sickle cell disease?
Answer: β-globin mutation (Glu→Val)
Explanation: Causes HbS polymerization.
46. Antibiotic causing tendon rupture?
Answer: Fluoroquinolones
Explanation: Risk increased in elderly and steroid users.
47. Normal pacemaker of the heart?
Answer: SA node
Explanation: Fastest spontaneous depolarization.
48. What enzyme does HIV use to replicate its genome?
Answer: Reverse transcriptase
Explanation: Converts RNA → DNA.
49. Condition caused by lack of ADH?
Answer: Diabetes insipidus
Explanation: Leads to dilute urine and polyuria.
50. What vitamin deficiency causes scurvy?
Answer: Vitamin C
Explanation: Needed for collagen hydroxylation.
Simon Downes, MD, PhD 