NUMS — Medical & Dental Entry Test

NUMS Biology — Digestion, Gaseous Exchange and Transport (Set 3)

Take the NUMS Biology — Digestion, Gaseous Exchange and Transport (Set 3): 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. A patient lacks the enzyme lactase. After drinking milk, he develops diarrhoea and gas. The best explanation is that:
- A. undigested lactose is fermented by colonic bacteria and draws water into the gut ✓
- B. bile is not released
- C. fat digestion is blocked
- D. lactose is converted into starch
Answer: A. undigested lactose is fermented by colonic bacteria and draws water into the gut
Explanation: Unabsorbed lactose raises osmotic load and is fermented, producing gas and watery stool.
Q2. Which enzyme and site correctly match?
- A. Pancreatic amylase – duodenum ✓
- B. Salivary amylase – stomach (active at pH 2)
- C. Trypsin – mouth
- D. Pepsin – small intestine
Answer: A. Pancreatic amylase – duodenum
Explanation: Pancreatic amylase digests starch in the duodenum; pepsin acts in the stomach, trypsin in the small intestine.
Q3. A person who has had the gall bladder removed is advised to avoid very fatty meals because:
- A. bile is no longer stored and released in a burst for emulsification ✓
- B. lipase is no longer produced by the pancreas
- C. bile salts are no longer synthesised by the liver
- D. fat is mainly absorbed in the stomach
Answer: A. bile is no longer stored and released in a burst for emulsification
Explanation: Bile is still made in the liver but not stored; emulsification of large fat loads is less efficient.
Q4. Secretin is released when acidic chyme enters the duodenum. Its main effect is to stimulate the pancreas to secrete:
- A. pancreatic lipase only
- B. pepsinogen
- C. insulin
- D. bicarbonate-rich fluid ✓
Answer: D. bicarbonate-rich fluid
Explanation: Secretin triggers watery alkaline secretion that neutralises the acid.
Q5. Which cells of the gastric gland secrete intrinsic factor needed for vitamin B₁₂ absorption?
- A. Mucous neck cells
- B. Chief cells
- C. Parietal cells ✓
- D. G cells
Answer: C. Parietal cells
Explanation: Parietal cells secrete HCl and intrinsic factor; chief cells secrete pepsinogen.

The other 25 questions

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Q6. After total removal of the stomach, which deficiency is most likely over time?
- A. Vitamin C
- B. Calcium
- C. Vitamin B₁₂
- D. Vitamin K
Q7. Peptic ulcers are most commonly caused by:
- A. Hepatitis virus
- B. Entamoeba
- C. Escherichia coli
- D. Helicobacter pylori infection
Q8. Fatty acids and monoglycerides absorbed by intestinal epithelial cells are packaged into chylomicrons and enter the:
- A. lacteals of the villi
- B. hepatic portal vein directly
- C. bile duct
- D. capillaries of the villi
Q9. Under normal conditions, which statement about the diaphragm during inspiration is correct?
- A. It increases the pressure inside the lungs
- B. It pushes air into the lungs
- C. It relaxes and domes upward
- D. It contracts and flattens, increasing thoracic volume
Q10. A person has a tidal volume of 500 mL, an inspiratory reserve volume of 3000 mL and an expiratory reserve volume of 1100 mL. His vital capacity is:
- A. 5700 mL
- B. 4100 mL
- C. 3500 mL
- D. 4600 mL
Q11. A person breathes 12 times per minute at 500 mL per breath with an anatomical dead space of 150 mL. What is the alveolar ventilation per minute?
- A. 6000 mL
- B. 4200 mL
- C. 4800 mL
- D. 1800 mL
Q12. Which change shifts the oxygen–haemoglobin dissociation curve to the right (releasing more O₂ to tissues)?
- A. Increased CO₂ and decreased pH
- B. Increased pH
- C. Decreased temperature
- D. Decreased CO₂
Q13. Fetal haemoglobin has a higher affinity for oxygen than adult haemoglobin so that:
- A. CO₂ is retained
- B. the fetus makes less red blood cells
- C. oxygen passes from maternal to fetal blood in the placenta
- D. oxygen leaves the fetal blood faster
Q14. Most CO₂ in the blood is carried as:
- A. carbaminohaemoglobin
- B. dissolved CO₂
- C. bicarbonate ions in plasma
- D. carbonic acid
Q15. During an asthma attack, breathing out becomes difficult mainly because:
- A. the pleural cavity fills with fluid
- B. alveolar walls are destroyed
- C. the diaphragm is paralysed
- D. bronchioles narrow due to smooth muscle contraction and inflammation
Q16. In emphysema, the main structural change is:
- A. narrowing of bronchi by mucus
- B. inflammation of the pleura
- C. infection with Mycobacterium
- D. destruction of alveolar walls, reducing surface area
Q17. The respiratory centre in the medulla is stimulated MOST strongly by an increase in:
- A. nitrogen
- B. blood CO₂ (and hence H⁺)
- C. blood glucose
- D. blood O₂
Q18. In the leaf of a plant, gaseous exchange occurs mainly through:
- A. xylem vessels
- B. the cuticle only
- C. stomata and the air spaces of the spongy mesophyll
- D. palisade cells touching the epidermis
Q19. Root hair cells absorb mineral ions mostly by:
- A. pinocytosis only
- B. simple osmosis
- C. transpiration pull
- D. active transport against concentration gradients
Q20. In the cohesion–tension theory, the continuous column of water in xylem is maintained mainly by:
- A. cohesion between water molecules and adhesion to vessel walls
- B. root pressure only
- C. active pumping by xylem cells
- D. osmosis in phloem
Q21. Which condition would DECREASE the rate of transpiration?
- A. Low humidity
- B. High humidity
- C. High wind speed
- D. High temperature
Q22. A potted plant covered by a plastic bag shows droplets on its inner surface. This best demonstrates:
- A. respiration
- B. transpiration
- C. guttation by root pressure only
- D. translocation
Q23. In the pressure-flow hypothesis, sap moves in phloem from:
- A. sink to source by diffusion
- B. cortex to xylem
- C. root to leaf by transpiration pull
- D. source to sink down a turgor pressure gradient
Q24. If a ring of bark (including phloem) is removed from a tree trunk, which change is expected above the ring after some weeks?
- A. Death of leaves in a day
- B. Loss of xylem
- C. Stopped water uptake at once
- D. Swelling because of accumulating sugars
Q25. Purkinje fibres are important because they:
- A. conduct the impulse rapidly through the ventricular walls so the ventricles contract together
- B. delay the impulse between atria and ventricles
- C. initiate the heartbeat
- D. supply the heart with blood
Q26. The delay of the impulse at the atrioventricular node ensures that:
- A. blood flows backward
- B. the ventricles contract before the atria
- C. the atria empty into the ventricles before ventricles contract
- D. the SA node resets
Q27. A person has a stroke volume of 70 mL and a heart rate of 72 beats per minute. Cardiac output is about:
- A. 5.0 L/min
- B. 50 L/min
- C. 0.5 L/min
- D. 1.0 L/min
Q28. The first heart sound ('lub') is produced by closure of the:
- A. Valves of the coronary sinus only
- B. Valves of the great veins
- C. Semilunar (aortic and pulmonary) valves
- D. Atrioventricular (bicuspid and tricuspid) valves
Q29. Compared with veins, arteries have:
- A. wider lumens
- B. valves throughout
- C. thicker walls with more elastic and muscular tissue
- D. lower blood pressure
Q30. Blood from the digestive tract passes through the liver before reaching the heart via the:
- A. hepatic artery
- B. pulmonary vein
- C. hepatic portal vein
- D. renal vein