NUMS — Medical & Dental Entry Test

NUMS Biology — Digestion, Gaseous Exchange and Transport (Set 6)

Take the NUMS Biology — Digestion, Gaseous Exchange and Transport (Set 6): 30 multiple-choice questions (40 minutes) with instant scoring and a full…

What this test covers

30 NUMS Biology

Sample questions with answers

The first 5 questions of this test, with the correct answer and explanation.

Q1. At rest a person's end-diastolic volume is 120 mL and end-systolic volume is 50 mL, with a heart rate of 75 beats per minute. What are the stroke volume and cardiac output?
- A. 70 mL and 5,250 mL per minute ✓
- B. 170 mL and 12,750 mL per minute
- C. 70 mL and 9,000 mL per minute
- D. 50 mL and 3,750 mL per minute
Answer: A. 70 mL and 5,250 mL per minute
Explanation: SV = EDV − ESV = 70 mL. CO = 70 × 75 = 5,250 mL per minute.
Q2. The same person (EDV 120 mL, ESV 50 mL) has an ejection fraction of about:
- A. 71%
- B. 83%
- C. 58% ✓
- D. 42%
Answer: C. 58%
Explanation: Ejection fraction = stroke volume ÷ end-diastolic volume = 70/120 ≈ 58%.
Q3. In a resting subject TV = 500 mL, IRV = 2,500 mL, ERV = 1,000 mL and RV = 1,200 mL. What is the total lung capacity?
- A. 4,000 mL
- B. 3,000 mL
- C. 5,200 mL ✓
- D. 4,200 mL
Answer: C. 5,200 mL
Explanation: TLC = TV + IRV + ERV + RV = 500 + 2,500 + 1,000 + 1,200 = 5,200 mL.
Q4. A person takes 15 breaths per minute, each with a volume of 400 mL, and the anatomical dead space is 150 mL. What is the alveolar ventilation per minute?
- A. 3,750 mL ✓
- B. 6,000 mL
- C. 2,250 mL
- D. 4,500 mL
Answer: A. 3,750 mL
Explanation: Alveolar ventilation = (TV − dead space) × rate = 250 × 15 = 3,750 mL per minute.
Q5. Fetal haemoglobin is half-saturated at a lower PO₂ than adult haemoglobin. What is the physiological advantage?
- A. It carries carbon dioxide more effectively than adult Hb does
- B. It is not affected by the Bohr effect at all
- C. It releases oxygen more easily to the placenta
- D. It takes up oxygen from maternal blood across the placenta ✓
Answer: D. It takes up oxygen from maternal blood across the placenta
Explanation: A left-shifted curve means higher affinity, so oxygen passes from maternal to fetal haemoglobin at the same PO₂.

The other 25 questions

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Q6. Acetazolamide inhibits carbonic anhydrase in red blood cells. What is a likely effect on CO₂ transport in systemic capillaries?
- A. Less CO₂ is carried as bicarbonate; more stays in solution
- B. The pH of the plasma rises sharply as less H⁺ forms
- C. More CO₂ is carried as bicarbonate, mostly in the plasma
- D. Haemoglobin releases much more oxygen to the working tissues
Q7. A patient poisoned with carbon monoxide has normal arterial PO₂ but feels weak and dizzy. Which statement is correct?
- A. Blood carries more O₂ because CO raises dissolved oxygen
- B. Total O₂ content is low because CO occupies haem sites
- C. Haemoglobin has been broken down into amino acids
- D. Oxygen content is normal because PO₂ is normal
Q8. A trained diver hyperventilates before a long breath-hold, then loses consciousness underwater before feeling a strong urge to breathe. What explains this?
- A. Carotid bodies respond only to a rise in blood pH
- B. Hyperventilation lowered CO₂, delaying the urge to breathe while O₂ ran low
- C. Hyperventilation raised blood O₂ stores by a large factor, preventing any hypoxia
- D. Hyperventilation raised blood CO₂, which removed the urge to breathe before O₂ fell
Q9. After a stab wound lets air into the pleural cavity, the lung on that side collapses. The main reason is that:
- A. intrapleural pressure reaches atmospheric, so the lung recoils
- B. surfactant is washed out of all the alveoli at once by the air
- C. alveoli fill with blood and so cannot expand against the chest wall
- D. the diaphragm stops receiving signals from the brain stem
Q10. Premature babies often have laboured breathing because their alveoli collapse at the end of each breath. The missing substance and its source are:
- A. mucus, made by goblet cells
- B. lysozyme, made by macrophages
- C. carbonic anhydrase, made by red blood cells
- D. surfactant, made by type II alveolar cells
Q11. Spirometry shows FEV₁/FVC of 0.45 (normal about 0.8) with raised residual volume. Which condition fits best?
- A. Pulmonary fibrosis, a restrictive disease with a high ratio
- B. Severe anaemia, which reduces lung volumes
- C. Emphysema, an obstructive disease with air trapping
- D. Complete paralysis of the diaphragm
Q12. Abscisic acid is sprayed on a leaf during drought. The guard cells respond by:
- A. gaining K⁺ and water, becoming turgid and opening the stoma
- B. losing K⁺ and water, becoming flaccid and closing the stoma
- C. producing starch to raise their solute potential
- D. dividing to produce additional pores
Q13. A potometer's capillary has an internal diameter of 1 mm. The air bubble moves 14 mm in 5 minutes. Taking π = 22/7, what is the rate of water uptake?
- A. 2.8 mm³ per minute
- B. 11 mm³ per minute
- C. 2.2 mm³ per minute
- D. 8.8 mm³ per minute
Q14. A woody stem is cut under water and then a small air bubble blocks one xylem vessel. Why does water movement in that vessel stop?
- A. The continuous cohesive water column is broken
- B. Phloem flow reverses in that vessel
- C. Osmosis from the root stops completely
- D. Water cannot pass through the vessel's cellulose wall
Q15. A ring of bark and phloem is removed from a woody stem. After some weeks the bark just above the ring swells, while roots below slowly starve. This shows that:
- A. sugars move down through phloem and accumulate above the ring
- B. sugars move upward in the xylem and so accumulate below the ring
- C. minerals move only through the bark and the phloem
- D. water moves downward through the phloem and the bark
Q16. Aphid stylets cut from a feeding aphid on a leaf exude sap for hours. Sap collected nearest the leaf is richer in sucrose than that nearer the roots. This supports which idea?
- A. Mass flow of sap from the source (leaf) toward sinks
- B. Companion cells store all sucrose
- C. Sieve plates stop sucrose from moving
- D. Sap flows from the roots towards the leaves in the xylem
Q17. Water droplets are seen at the leaf margins of a grass seedling early in a humid morning. They result from:
- A. transpiration of water vapour from the stomata of the leaf
- B. condensation of dew on a waxy cuticle
- C. active secretion of salts by guard cells
- D. root pressure forcing water out of hydathodes (guttation)
Q18. A patient on warfarin has a prolonged clotting time. Warfarin acts by:
- A. destroying fibrin threads soon after they have formed
- B. inactivating all the calcium ions found in the plasma
- C. increasing the number of platelets in the circulation
- D. antagonising the action of vitamin K in the liver
Q19. Blood flows at about 5 L/min through an aorta of cross-sectional area 3 cm² and through capillaries with total cross-sectional area 3,000 cm². Compared with the aorta, flow velocity in the capillaries is:
- A. about 10 times lower
- B. about 1,000 times lower
- C. about 1,000 times higher
- D. the same in both
Q20. A patient with severe liver disease has swollen ankles. Which change best explains this oedema?
- A. Low plasma albumin reduces oncotic pressure
- B. Excess blood vessel constriction lowers hydrostatic pressure
- C. High plasma albumin raises oncotic pressure in tissues
- D. Raised levels of haemoglobin pull water out
Q21. An ECG shows regular P waves, but every third P wave is not followed by a QRS complex. What is the most likely problem?
- A. Damage to the aortic valve
- B. Atrial fibrillation with chaotic P waves
- C. Failure of the sinoatrial node to fire
- D. Intermittent block at the AV node
Q22. A transplanted heart is not connected to the vagus nerve. Compared with a normal heart, its resting rate is likely to be:
- A. the same, because the SA node is controlled only by the brain
- B. zero, because the SA node needs a nerve to fire
- C. lower, because it lacks sympathetic stimulation
- D. higher, because vagal slowing of the SA node is absent
Q23. A patient with a gallstone blocking the bile duct passes pale, fatty stools. Which explanation is correct?
- A. Pancreatic lipase is destroyed in the bile
- B. Bile carries lactase to the small intestine
- C. Bile salts cannot reach the duodenum
- D. Bile is needed to digest proteins, which are then not absorbed
Q24. Acid chyme entering the duodenum stimulates release of a hormone which causes the pancreas to secrete a watery, bicarbonate-rich juice. The hormone is:
- A. cholecystokinin only
- B. gastrin
- C. insulin
- D. secretin
Q25. After drinking milk, a person has bloating and watery diarrhoea. Which explanation fits lactose intolerance?
- A. Undigested lactose draws in water and is fermented by bacteria
- B. The stomach produces too little pepsin to digest the lactose present
- C. Lactose is digested too fast and floods the blood with glucose
- D. Bile salts are absent, so lactose is not emulsified for digestion
Q26. A drug that blocks the H⁺/K⁺ pump of parietal cells is given to an ulcer patient. The direct effect on protein digestion is that:
- A. less pepsinogen is activated to pepsin when gastric pH rises
- B. trypsin cannot be activated in the duodenum
- C. more pepsin is made because acid normally inhibits its release
- D. proteins are absorbed unchanged in the stomach
Q27. After a fatty meal, the digested fat is absorbed by the epithelial cells of a villus. Which route do the resynthesised fats take?
- A. Fatty acids enter villus capillaries and go straight to the liver
- B. Glycerol and bile salts enter the hepatic portal vein
- C. Triglycerides diffuse into the lumen of the colon
- D. Chylomicrons enter the lacteal and reach blood via the lymph
Q28. In a fish gill, water and blood flow in opposite directions across the lamellae. Compared with parallel flow, countercurrent flow allows:
- A. a diffusion gradient to be kept along the whole lamella
- B. blood to leave with lower O₂ than the water leaving the gills
- C. less oxygen to be absorbed but more CO₂ to leave
- D. a maximum of 50% of the oxygen to be taken up
Q29. Haemoglobin binds 1.34 mL of O₂ per gram when saturated. Blood with 15 g Hb per 100 mL leaves the lungs 100% saturated and returns to the lungs 75% saturated. How much O₂ is unloaded per 100 mL, ignoring dissolved O₂?
- A. 5.0 mL
- B. 10.1 mL
- C. 20.1 mL
- D. 15.1 mL
Q30. Rhythmic back-and-forth contractions of the small intestine that mix chyme with enzymes without moving it far along the gut are called:
- A. segmentation
- B. antiperistalsis
- C. mass movement
- D. peristalsis