Revision MEGA QUIZ

First-Year Medical Mega Quiz: Physiology, Pathophysiology, and Pharmacology

Test your understanding of core medical concepts across systems! This 40-question quiz is packed with clinical vignettes and applied physiology from topics like asthma, digestion, gas exchange, renal handling, antibiotics, ECGs, liver disease, pharmacology and more. Can you get through the full set?

Click 'Check Answers' at the bottom to see your score and explanations. Use 'Try Again' to clear your responses and start over.

1. A 48-year-old man presents with heartburn and acid reflux. He has been taking over-the-counter antacids for symptom relief.
What is the most likely mechanism of action of an antacid?

A. Binds bile salts
B. Blocks histamine H₂ receptors
C. Neutralises luminal gastric acid
D. Inhibits the proton pump
E. Coats the gastric mucosa

Explanation: Antacids work by directly neutralising gastric acid in the stomach lumen. They provide quick but temporary relief and do not affect acid production mechanisms like PPIs or H₂ blockers.

2. A 47-year-old man presents with persistent heartburn and regurgitation. He has a BMI of 34 and often lies down after large meals.
Which factor most likely contributes to his reflux symptoms?

A. Increased gastric acid production
B. Helicobacter pylori infection
C. Delayed gastric emptying
D. Reduced lower oesophageal sphincter tone
E. Gallstone disease

Explanation: GORD is primarily due to reduced tone or dysfunction of the lower oesophageal sphincter (LOS), especially in the setting of obesity or postprandial reclining. This allows acid to reflux into the oesophagus.

3. A 6-year-old boy presents with a persistent dry cough and wheezing that worsens at night and during exercise. His peak flow varies significantly across the day.
Which mechanism best explains his symptoms?

A. Upper airway obstruction
B. Decreased surfactant production
C. Reversible bronchial hyperresponsiveness
D. Impaired mucociliary clearance
E. Permanent airway fibrosis

Explanation: Asthma involves reversible airway obstruction and bronchial hyperresponsiveness. Variability in peak flow is a hallmark diagnostic clue.

4. A 70-year-old man presents with weakness and low urine output. Blood tests reveal elevated urea and creatinine.
Which structure in the nephron is primarily responsible for filtering blood?

A. Loop of Henle
B. Collecting duct
C. Glomerulus
D. Proximal tubule
E. Macula densa

Explanation: The glomerulus filters blood plasma into Bowman’s capsule under pressure. It’s the first step in urine formation.

5. A 61-year-old man presents with black tarry stools and dizziness. On examination, he is pale and hypotensive.
Which site is most likely responsible for the bleeding?

A. Lower colon
B. Upper gastrointestinal tract
C. Small bowel angiodysplasia
D. Haemorrhoids
E. Inflammatory bowel disease

Explanation: Melena (black, tarry stools) indicates digested blood from an upper GI source, such as peptic ulcers or oesophageal varices.

6. A 19-year-old woman becomes dehydrated after prolonged exercise in hot weather.
Which hormone is primarily responsible for increasing water reabsorption in her kidneys?

A. Renin
B. Angiotensin II
C. Aldosterone
D. Antidiuretic hormone (ADH)
E. Atrial natriuretic peptide

Explanation: ADH promotes insertion of aquaporins in the collecting ducts, increasing water reabsorption to help maintain blood volume during dehydration.

7. A 45-year-old man presents with persistently elevated liver enzymes. LFTs show AST 210 IU/L (normal <40), ALT 90 IU/L (normal <45).
What is the most likely explanation for this pattern?

A. Bile duct obstruction
B. Viral hepatitis
C. Alcoholic mitochondrial injury
D. Iron overload
E. Cholestatic hepatitis

Explanation: Alcoholic liver disease typically shows AST > ALT due to mitochondrial injury from acetaldehyde. AST is more concentrated in mitochondria than ALT.

8. A 14-year-old boy with asthma uses a short-acting beta agonist multiple times a day and needs a long-term controller.
Which drug class is most appropriate for long-term asthma prevention?

A. Anticholinergics
B. Leukotriene receptor antagonists
C. Long-acting beta agonists (LABAs)
D. Inhaled corticosteroids
E. Methylxanthines

Explanation: Inhaled corticosteroids are the most effective preventer for persistent asthma. They reduce inflammation and airway hyperresponsiveness over time.

9. A 36-year-old man with chronic pancreatitis presents with greasy, pale stools and weight loss despite normal eating.
Which process is most impaired?

A. Gastric acid production
B. Salivary enzyme function
C. Pancreatic enzyme secretion
D. Brush border enzyme activity
E. Bile acid synthesis

Explanation: Pancreatic enzymes are essential for digestion of fats, proteins, and carbohydrates. Deficiency causes malabsorption and steatorrhoea.

10. A 45-year-old woman is started on a loop diuretic for leg swelling due to heart failure.
Which part of the nephron is the main site of action for loop diuretics?

A. Proximal convoluted tubule
B. Descending loop of Henle
C. Thick ascending limb of loop of Henle
D. Distal convoluted tubule
E. Collecting duct

Explanation: Loop diuretics inhibit the Na⁺/K⁺/2Cl⁻ cotransporter in the thick ascending limb, reducing sodium reabsorption and promoting diuresis.

11. A 45-year-old man presents with chronic heartburn. He is prescribed a proton pump inhibitor (PPI).
Which enzyme does this class of drugs inhibit?

A. Carbonic anhydrase
B. Na⁺/K⁺ ATPase
C. H⁺/K⁺ ATPase
D. Pepsinogen
E. Histidine decarboxylase

Explanation: PPIs irreversibly inhibit the H⁺/K⁺ ATPase in gastric parietal cells, preventing acid secretion.

12. A 28-year-old woman presents with fatigue and signs of chronic liver disease. Her liver function is abnormal.
Which clinical sign most directly reflects impaired liver synthetic function?

A. Jaundice
B. Spider naevi
C. Palmar erythema
D. Bruising
E. Ascites

Explanation: Bruising reflects decreased production of clotting factors, which are synthesized by the liver—an important synthetic function.

13. A 27-year-old man is prescribed a β-lactam antibiotic for a sore throat.
What is the main mechanism of action of this drug class?

A. Inhibits bacterial protein synthesis
B. Damages bacterial DNA
C. Inhibits bacterial cell wall synthesis
D. Alters folate metabolism
E. Disrupts bacterial membranes

Explanation: β-lactams (like penicillins) inhibit peptidoglycan cross-linking in the bacterial cell wall, weakening it and causing lysis.

14. A 60-year-old man taking a potassium-sparing diuretic is found to have a serum potassium level of 6.1 mmol/L.
Which nephron segment is primarily responsible for potassium secretion?

A. Proximal tubule
B. Descending loop of Henle
C. Thick ascending limb
D. Distal convoluted tubule
E. Collecting duct

Explanation: The collecting duct is the primary site of regulated potassium secretion, under aldosterone influence. Potassium-sparing diuretics inhibit this.

15. A 52-year-old man undergoes pre-op ECG. It shows an irregularly irregular rhythm with absent P waves.
What is the most likely diagnosis?

A. Sinus arrhythmia
B. Atrial flutter
C. Ventricular ectopy
D. Atrial fibrillation
E. Complete heart block

Explanation: Atrial fibrillation shows an irregularly irregular rhythm with no clear P waves and variable ventricular response.

16. A 25-year-old man experiences shortness of breath after swimming underwater. ABG shows low PaO₂ and normal PaCO₂.
What is the most likely cause of this gas abnormality?

A. Hypoventilation
B. Anaemia
C. Ventilation-perfusion mismatch
D. Carbon monoxide poisoning
E. Increased dead space

Explanation: V/Q mismatch causes reduced oxygenation but may spare CO₂ due to its higher solubility and diffusion rate.

17. A 60-year-old woman with hypertension and diabetes is prescribed an ACE inhibitor.
What is the primary mechanism of action of this class of drugs?

A. Beta-adrenergic receptor blockade
B. Calcium channel inhibition
C. Inhibition of angiotensin-converting enzyme
D. Aldosterone receptor antagonism
E. Alpha-1 receptor blockade

Explanation: ACE inhibitors reduce angiotensin II production, decreasing vasoconstriction and aldosterone secretion. This lowers BP and protects kidneys.

18. A 35-year-old man with a long history of alcohol use is found to have hepatic steatosis on imaging.
What is the most likely underlying mechanism?

A. Iron overload
B. Insulin resistance
C. Bile salt deficiency
D. Increased lipogenesis
E. Mitochondrial dysfunction from acetaldehyde

Explanation: Alcohol metabolism generates acetaldehyde, which damages mitochondria, leading to impaired β-oxidation and fat accumulation in hepatocytes.

19. A 27-year-old man donates blood. Shortly afterward, he feels dizzy when standing. Baroreceptors help maintain perfusion.
Where are these pressure sensors located?

A. Aortic valve and coronary sinus
B. Pulmonary artery and left atrium
C. Carotid sinus and aortic arch
D. Circle of Willis and cerebellum
E. Subclavian artery and jugular vein

Explanation: Baroreceptors in the carotid sinus and aortic arch detect pressure changes and trigger reflex adjustments in heart rate and vascular tone.

20. A 37-year-old woman from a refugee background presents with fatigue and anxiety. She is a single parent with limited English and access to care.
What concept best explains how these factors interact to affect her health?

A. Cultural competence
B. Health literacy
C. Intersectionality
D. Acculturation
E. Primary prevention

Explanation: Intersectionality considers how overlapping social identities (e.g. gender, ethnicity, language, income) intersect to shape health vulnerability and access.

Halfway there! You've answered 20 questions. Take a breather, then keep going!

21. A 58-year-old man presents with central chest pain radiating to his left arm. ECG shows ST-segment 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
E. Diagonal branch

Explanation: ST elevation in leads II, III, and aVF suggests an inferior MI, most commonly due to occlusion of the right coronary artery (RCA), which supplies the inferior wall in most people.

22. A 68-year-old patient with advanced cancer is offered chemotherapy that may extend life by 2–3 months but is associated with fatigue and nausea. The patient is unsure whether to proceed and seeks your advice.
Which of the following ethical principles is best demonstrated by exploring the patient's values and supporting their own informed decision-making?

A. Justice
B. Autonomy
C. Beneficence
D. Non-maleficence
E. Confidentiality

Explanation: Autonomy refers to respecting the patient's right to make their own decisions about care, based on their values and preferences. Exploring treatment options and helping the patient make an informed decision upholds this principle.

23. A 22-year-old student presents with fever, cough, and pleuritic chest pain. Examination reveals bronchial breath sounds over the right lower lobe.
Which of the following findings is most likely on chest X-ray?

A. Hyperinflation with flattened diaphragm
B. Patchy peripheral infiltrates
C. Lobar consolidation
D. Bilateral reticulonodular opacities
E. Widened mediastinum

Explanation: Bacterial pneumonia (commonly Streptococcus pneumoniae) often causes dense lobar consolidation with air bronchograms, correlating with bronchial breath sounds on auscultation.

24. A 30-year-old woman is diagnosed with a Helicobacter pylori infection after presenting with epigastric pain.
Which of the following mechanisms best explains how H. pylori contributes to gastric ulcer formation?

A. Inhibits acid secretion
B. Triggers eosinophilic inflammation
C. Produces urease to neutralise gastric acid
D. Stimulates mucous production
E. Enhances prostaglandin synthesis

Explanation: H. pylori produces urease, which breaks down urea into ammonia, neutralising acid locally. This allows the bacterium to survive in the stomach lining, where it causes inflammation and mucosal damage.

25. A 3-year-old child aspirates a peanut and presents with sudden wheeze and decreased breath sounds on the right.
Which physiological mechanism best explains the acute change?

A. Impaired surfactant production
B. Air trapping due to ball-valve obstruction
C. Increased alveolar perfusion
D. Fibrosis of bronchial tissue
E. Increased tidal volume

Explanation: A foreign body can act as a ball-valve, allowing air in during inspiration but not out during expiration. This leads to hyperinflation and wheeze.

26. A 20-year-old man ascends to high altitude and develops shortness of breath and tachypnoea.
Which of the following best describes the initial cause of his increased ventilation?

A. Central chemoreceptor response to pH
B. Peripheral chemoreceptor response to hypoxia
C. Activation of stretch receptors
D. Increased sympathetic tone
E. Elevated CO₂ in CSF

Explanation: At high altitude, arterial oxygen levels fall, stimulating peripheral chemoreceptors (in the carotid and aortic bodies) to increase ventilation.

27. A 40-year-old woman presents with epigastric discomfort and indigestion. She has been taking high-dose ibuprofen for a recent back injury. Endoscopy reveals gastric erosions.
Which of the following best explains her findings?

A. Excess histamine release
B. Immune-mediated attack on mucosa
C. Reduced mucosal prostaglandin synthesis
D. Increased gastric acid production
E. H. pylori urease production

Explanation: NSAIDs inhibit COX enzymes, reducing prostaglandin synthesis. This weakens mucosal defences against acid and pepsin, leading to erosions and gastritis.

28. A 32-year-old man undergoes pulmonary function testing. His oxygen levels drop significantly when lying on his left side.
What is the most likely mechanism of this finding?

A. V/Q mismatch due to gravity-dependent shunting
B. Impaired diaphragmatic contraction
C. Reduced surfactant production
D. Decreased alveolar compliance
E. Hypercapnic respiratory failure

Explanation: In conditions like unilateral pneumonia or pulmonary AV malformation, gravity can worsen ventilation-perfusion mismatch (V/Q mismatch), causing hypoxia in certain positions (orthodeoxia).

29. A 25-year-old man sustains a superficial abrasion to his forearm while playing football. The wound is painful but does not bleed heavily.
Which layer of skin is most likely to be primarily affected?

A. Hypodermis
B. Reticular dermis
C. Epidermis
D. Papillary dermis
E. Subcutaneous fascia

Explanation: Superficial abrasions typically involve only the epidermis, the outermost layer of the skin. This layer lacks blood vessels, so bleeding is minimal, though the area may be painful due to exposed nerve endings.

30. A 3-day-old newborn is noted to have mild jaundice on examination but is otherwise feeding well and gaining weight. There are no signs of infection or haemolysis.
Which of the following best explains the most likely cause of this jaundice?

A. ABO incompatibility
B. Neonatal sepsis
C. Immature hepatic conjugation of bilirubin
D. Biliary atresia
E. Breast milk jaundice

Explanation: Physiological jaundice in newborns is common and usually peaks around day 3. It is due to the immature activity of hepatic UDP-glucuronosyltransferase, the enzyme responsible for bilirubin conjugation. As liver function matures, bilirubin levels decline.

31. A 62-year-old man presents with central chest pain and is diagnosed with acute coronary syndrome. He is given aspirin immediately in the emergency department.
What is the main reason aspirin is used in this scenario?

A. Reduce heart rate
B. Promote coronary vasodilation
C. Inhibit platelet aggregation
D. Stabilise cardiac myocyte membranes
E. Prevent arrhythmias

Explanation: Aspirin is used in acute coronary syndrome to inhibit platelet aggregation. It irreversibly inhibits cyclooxygenase (COX), preventing thromboxane A2 formation and reducing further thrombus formation in coronary arteries.

32. A 19-year-old presents with abdominal pain and diarrhoea. Colonoscopy reveals patchy areas of inflammation, and biopsy shows transmural granulomatous inflammation.
Which of the following best explains the pathophysiological process involved?

A. Excessive Th2-mediated cytokine response
B. Decreased epithelial cell turnover
C. Dysregulated mucosal immune response to gut microbiota
D. IgE-mediated mast cell degranulation
E. Autoimmune destruction of parietal cells

Explanation: Inflammatory bowel diseases, including Crohn’s disease and ulcerative colitis, involve a dysregulated immune response to intestinal microbiota. In Crohn’s, a Th1/Th17-type response leads to transmural inflammation and granuloma formation, often in a patchy distribution.

33. A 10-year-old boy presents with recurrent wheezing, shortness of breath, and night-time cough. He is diagnosed with asthma.
Which of the following best explains the underlying pathophysiology of his condition?

A. Destruction of alveolar walls
B. Loss of pulmonary surfactant
C. Collapse of tracheal cartilage
D. Reversible airway inflammation and bronchial hyperresponsiveness
E. Permanent fibrosis of bronchial walls

Explanation: Asthma is characterised by reversible airway obstruction caused by chronic inflammation, bronchial hyperreactivity, and smooth muscle constriction. Mucous hypersecretion and airway remodelling can occur if poorly controlled.

34. A 7-year-old boy develops generalised urticaria and facial swelling shortly after eating a peanut-containing snack. He has no known prior allergies.
This presentation most likely involves which type of hypersensitivity reaction?

A. Type II – antibody-mediated cytotoxic
B. Type III – immune complex deposition
C. Type I – immediate hypersensitivity
D. Type IV – delayed-type hypersensitivity
E. Type V – stimulatory antibody response

Explanation: Type I hypersensitivity involves IgE-mediated activation of mast cells and basophils in response to allergens. It leads to rapid onset of symptoms such as urticaria, angioedema, and anaphylaxis after exposure to substances like peanuts.

35. A 20-year-old university student develops fever, sore throat, and fatigue. Blood tests show lymphocytosis with atypical lymphocytes. Infectious mononucleosis is suspected.
Which type of immune response is primarily responsible for controlling viral infections?

A. Eosinophil activation and IgE production
B. Complement activation via the classical pathway
C. Cytotoxic T lymphocyte (CD8⁺)–mediated killing of infected cells
D. Mast cell degranulation and histamine release
E. Th2-mediated B cell class switching

Explanation: Viral infections are primarily controlled by CD8⁺ cytotoxic T lymphocytes, which recognise and destroy virus-infected cells. This cell-mediated immune response is crucial for clearing intracellular pathogens such as Epstein–Barr virus in infectious mononucleosis.

36. A 65-year-old man with ischaemic heart disease is prescribed a cardioselective beta-blocker. His blood pressure and heart rate improve over the next few weeks.
Which of the following best describes the mechanism of action of beta-blockers?

A. Stimulate beta-1 receptors to increase contractility
B. Block alpha-1 receptors to reduce vascular resistance
C. Inhibit beta-1 receptors to reduce heart rate and contractility
D. Block beta-2 receptors to cause coronary vasodilation
E. Inhibit renin production by blocking aldosterone receptors

Explanation: Beta-blockers work by inhibiting beta-adrenergic receptors, especially beta-1 receptors in the heart, reducing heart rate and myocardial contractility. This decreases oxygen demand. Cardioselective beta-blockers primarily target beta-1 receptors but at higher doses may also block beta-2 receptors, which can cause bronchoconstriction and peripheral vasoconstriction.

37. A medical student on placement in a regional Aboriginal Medical Service learns about the historical and cultural context of Aboriginal health in Australia.
Which of the following best reflects a key principle of trauma-informed care in this setting?

A. Prioritising efficiency over patient storytelling
B. Encouraging compliance by reinforcing medical authority
C. Focusing only on current symptoms to avoid re-traumatisation
D. Acknowledging the impact of colonisation and creating a culturally safe space
E. Limiting family involvement to maintain confidentiality

Explanation: Trauma-informed care in Aboriginal health settings involves recognising the lasting impacts of colonisation, dispossession, and intergenerational trauma. Creating culturally safe environments and acknowledging these historical factors help build trust and support healing.

38. A 23-year-old athlete increases protein intake to support muscle growth. He asks how the body breaks down excess amino acids.
What is the first major step in amino acid catabolism?

A. Conversion to glucose via gluconeogenesis
B. Transamination to remove the amino group
C. Deamination and conversion to urea for excretion
D. Direct conversion to acetyl-CoA
E. Storage as glycogen in liver and muscle

Explanation: Amino acids cannot be stored, so excess protein undergoes catabolism. The nitrogen-containing amino group is first removed via transamination and then deaminated to form ammonia, which is converted to urea in the liver for excretion. The carbon skeletons may be used for energy.

39. A 19-year-old athlete undergoes a pre-participation ECG. His QT interval is prolonged.
Which phase of the ventricular action potential is most affected by delayed repolarisation?

A. Phase 0 – rapid Na⁺ influx
B. Phase 1 – early K⁺ efflux
C. Phase 2 – plateau (Ca²⁺ influx and K⁺ efflux)
D. Phase 3 – delayed rectifier K⁺ efflux
E. Phase 4 – resting membrane potential

Explanation: Prolonged QT reflects delayed repolarisation during phase 3, when K⁺ channels return the membrane potential to baseline. This prolongs ventricular recovery and can increase arrhythmia risk.

40. A 42-year-old woman with known asthma experiences wheezing and shortness of breath after taking aspirin for a headache.
Which mechanism best explains how aspirin can exacerbate asthma in some patients?

A. Increased histamine release from mast cells
B. Direct bronchial smooth muscle contraction
C. Shunting arachidonic acid metabolism towards leukotriene production
D. Enhanced parasympathetic tone in the airways
E. Blockade of β2-adrenoceptors on airway smooth muscle

Explanation: Aspirin inhibits cyclooxygenase (COX), which normally converts arachidonic acid into prostaglandins. In aspirin-sensitive asthma, this shunts arachidonic acid metabolism down the 5-lipoxygenase pathway, increasing leukotriene production. Leukotrienes are potent bronchoconstrictors and contribute to airway inflammation and hyperresponsiveness—Lyndal’s favourite pathway in action!

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