MBBS Cheat Sheet 2026

The 30 highest-yield MBBS facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is the most common cause of community-acquired pneumonia (CAP) in adults? → Streptococcus pneumoniae
2. During exercise, which of the following best explains the increase in cardiac output? → Increased sympathetic activity and venous return
3. The Frank-Starling mechanism of the heart states that: → Stroke volume increases with increased end-diastolic volume
4. Which segment of the nephron is impermeable to water under all conditions? → Thick ascending loop of Henle
5. A 3-year-old presents with a 'barking cough' and inspiratory stridor. Which virus is the most common cause of this condition (croup)? → Parainfluenza virus
6. Which drug class is used as first-line treatment for type 2 diabetes and acts by reducing hepatic glucose production? → Biguanides (Metformin)
7. The DNA double helix is held together by which type of bonds between base pairs? → Hydrogen bonds
8. The Hering-Breuer reflex is mediated by which receptors? → Pulmonary stretch receptors (slowly adapting)
9. The inhaled anesthetic you intend to employ has an extremely high MAC. High minimum alveolar concentration (MAC) anesthetics typically: → Less lipid soluble
10. In which organelle does the citric acid (Krebs) cycle occur? → Mitochondrial matrix
11. Chyle leaks are frequently treated by adding extra of the following fatty acids to the patient's diet: → Medium-chain
12. Which antibiotic class inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs)? → Beta-lactams
13. Which structure passes through the foramen ovale of the skull base? → CN V3 (mandibular nerve)
14. Clostridium tetani produces tetanospasmin, which causes spastic paralysis. What is its mechanism of action? → Inhibits release of inhibitory neurotransmitters glycine and GABA
15. Psammoma bodies are calcified concentric rings found in which tumor? → Papillary thyroid carcinoma
16. Which of the following is the reversal agent for heparin toxicity? → Protamine sulfate
17. Which of the following is an example of Type III hypersensitivity (immune complex-mediated)? → Serum sickness
18. Which type of infarction is characterized by pale, firm tissue without hemorrhage? → White (anemic) infarction
19. Kartagener syndrome is characterized by bronchiectasis, sinusitis, and situs inversus due to defect in which structure? → Microtubules in cilia (dynein arms)
20. Which hepatitis virus is transmitted via the fecal-oral route and does NOT cause chronic infection? → Hepatitis A
21. Which antiepileptic drug acts by prolonging the inactivation state of voltage-gated sodium channels? → Phenytoin
22. Which organism is the most common cause of neonatal meningitis and is acquired from the maternal vaginal flora during delivery? → Streptococcus agalactiae (Group B Strep)
23. Which investigation is considered the gold standard for diagnosing deep vein thrombosis (DVT)? → Contrast venography
24. Digoxin toxicity is worsened by which electrolyte imbalance? → Hypokalemia
25. The McBurney's point, used to locate appendiceal tenderness, is located at what anatomical position? → 1/3 of the way from the right ASIS to the umbilicus
26. Which hormone causes water reabsorption in the collecting duct by inserting aquaporin-2 channels? → Antidiuretic hormone (ADH)
27. In the complement system, which component acts as the convergence point for both the classical and alternative pathways? → C3
28. Which muscle is innervated by both the anterior and posterior divisions of the obturator nerve? → Adductor magnus
29. Which type of necrosis is characteristically seen in tuberculosis? → Caseous necrosis
30. Which organism causes 'walking pneumonia' and lacks a cell wall, making it intrinsically resistant to beta-lactam antibiotics? → Mycoplasma pneumoniae