NUMS — Medical & Dental Entry Test

NUMS Biology — Nervous and Chemical Coordination, Immunity (Set 2)

Take the NUMS Biology — Nervous and Chemical Coordination, Immunity (Set 2): 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. Neurons that carry impulses from the central nervous system to muscles and glands are:
- A. Motor (efferent) neurons ✓
- B. Relay neurons
- C. Sensory (afferent) neurons
- D. Receptor cells
Answer: A. Motor (efferent) neurons
Explanation: Motor neurons carry impulses away from the CNS to effectors; sensory neurons carry them towards the CNS.
Q2. In the peripheral nervous system, the myelin sheath around axons is formed by:
- A. Astrocytes
- B. Schwann cells ✓
- C. Microglia
- D. Oligodendrocytes
Answer: B. Schwann cells
Explanation: Schwann cells wrap around peripheral axons; oligodendrocytes form myelin in the CNS.
Q3. If a neuron is placed in a medium with a much lower Na⁺ concentration than normal, the action potential will:
- A. Become permanently depolarised
- B. Be unaffected because only K⁺ matters
- C. Have a larger peak
- D. Have a smaller peak (less positive overshoot) ✓
Answer: D. Have a smaller peak (less positive overshoot)
Explanation: Depolarisation depends on Na⁺ influx down its gradient; reducing external Na⁺ reduces the gradient, so the peak potential is lower.
Q4. Repolarisation of a neuron after the peak of an action potential is mainly due to:
- A. Na⁺ moving into the axon
- B. Cl⁻ moving out of the axon
- C. Ca²⁺ moving into the axon
- D. Opening of voltage-gated K⁺ channels and K⁺ moving out ✓
Answer: D. Opening of voltage-gated K⁺ channels and K⁺ moving out
Explanation: At the peak, Na⁺ channels inactivate and K⁺ channels open; K⁺ efflux returns the inside to a negative potential.
Q5. Brief hyperpolarisation after an action potential (the potential falling below −70 mV) occurs because:
- A. K⁺ channels stay open slightly longer than needed ✓
- B. Acetylcholine is released
- C. The Na⁺/K⁺ pump stops working
- D. Na⁺ channels remain open
Answer: A. K⁺ channels stay open slightly longer than needed
Explanation: Voltage-gated K⁺ channels close slowly, so extra K⁺ leaves and the membrane briefly becomes more negative than resting potential.

The other 25 questions

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Q6. A myelinated axon conducts at 100 m/s. How long will an impulse take to travel 0.8 m from the spinal cord to a toe muscle?
- A. 80 ms
- B. 125 ms
- C. 0.8 ms
- D. 8 ms
Q7. Neurotransmitter release at a synapse is triggered when an action potential opens voltage-gated channels for:
- A. Potassium ions in the synaptic cleft
- B. Chloride ions in the postsynaptic membrane
- C. Sodium ions in the synaptic vesicles
- D. Calcium ions in the presynaptic membrane
Q8. Curare, an arrow poison, binds to acetylcholine receptors on muscle cells without opening them. Its effect is:
- A. Increased acetylcholine breakdown causing spasms
- B. Continuous muscle contraction
- C. Muscle paralysis because acetylcholine cannot depolarise the muscle
- D. Faster nerve conduction
Q9. An inhibitory neurotransmitter opens Cl⁻ channels in the postsynaptic membrane. This makes the postsynaptic neuron:
- A. Hyperpolarised and less likely to fire
- B. Depolarised and more likely to fire
- C. Release more neurotransmitter
- D. Permanently refractory
Q10. Summation at a synapse means that:
- A. One impulse always triggers several action potentials
- B. Several sub-threshold impulses together can produce an action potential in the postsynaptic neuron
- C. Impulses travel in both directions
- D. Neurotransmitter is recycled faster
Q11. A stroke damages the left cerebral hemisphere in the region controlling movement. Which symptom is expected?
- A. Loss of heart rate control
- B. Loss of balance only
- C. Weakness or paralysis of the right side of the body
- D. Paralysis of the left side of the body
Q12. Which part of the brain links the nervous and endocrine systems by controlling the pituitary gland?
- A. Medulla oblongata
- B. Corpus callosum
- C. Cerebellum
- D. Hypothalamus
Q13. A patient with fever, headache and a stiff neck is diagnosed with inflammation of the protective membranes around the brain and spinal cord. These membranes are the:
- A. Pleura
- B. Meninges
- C. Pericardium
- D. Myelin sheaths
Q14. After a heavy meal, digestion is promoted and heart rate slows. This is controlled by the:
- A. Sympathetic nervous system
- B. Cerebellum
- C. Somatic nervous system
- D. Parasympathetic nervous system
Q15. Pacinian corpuscles in the skin respond to:
- A. Temperature only
- B. Pressure and vibration
- C. Chemicals in food
- D. Light
Q16. Epilepsy is best described as:
- A. Loss of dopamine-producing neurons
- B. Destruction of myelin by the immune system
- C. Recurrent seizures due to sudden abnormal bursts of electrical activity in the brain
- D. Accumulation of amyloid plaques
Q17. Insulin cannot enter its target cells but still causes them to take up glucose. This is because insulin:
- A. Diffuses through the membrane to the nucleus
- B. Directly carries glucose into the cell
- C. Is converted into glucose inside the cell
- D. Binds a membrane receptor that causes glucose transporters (GLUT4) to move to the cell surface
Q18. Between meals, falling blood glucose stimulates the α-cells of the islets of Langerhans to secrete:
- A. Insulin, which promotes glycogen synthesis
- B. Somatostatin, which raises blood glucose
- C. Adrenaline, which stores glucose
- D. Glucagon, which promotes glycogen breakdown in the liver
Q19. In type 1 diabetes, the patient needs insulin injections, whereas many type 2 patients do not initially. This is because in type 1:
- A. Too much glucagon is made
- B. Cells are resistant to insulin despite high levels
- C. The kidneys reabsorb no glucose
- D. Autoimmune destruction of β-cells means little or no insulin is produced
Q20. Cortisol, released during long-term stress, raises blood glucose mainly by:
- A. Stimulating gluconeogenesis from amino acids
- B. Converting glucose into glycogen
- C. Increasing insulin release
- D. Blocking glycogen breakdown
Q21. Which hormone is released by the posterior pituitary?
- A. Growth hormone
- B. Prolactin
- C. Antidiuretic hormone
- D. Thyroid-stimulating hormone
Q22. A person takes high doses of thyroxine tablets for several months. What happens to their TSH level and own thyroid gland activity?
- A. TSH rises and the thyroid enlarges
- B. TSH rises but the thyroid becomes less active
- C. TSH falls and the thyroid becomes less active
- D. Both are unchanged
Q23. A patient has weight loss, a fast heart rate, heat intolerance and bulging eyes. These signs suggest:
- A. Hypothyroidism (myxoedema)
- B. Diabetes insipidus
- C. Addison's disease
- D. Hyperthyroidism (Graves' disease)
Q24. Farmers spray gibberellins on seedless grape vines mainly to:
- A. Make the grapes ripen by producing ethylene
- B. Cause leaves to fall
- C. Close stomata during drought
- D. Increase the size of the grapes and elongate the stalks
Q25. Ripe bananas placed in a bag with unripe ones speed up their ripening. The gas responsible is:
- A. Ethylene
- B. Auxin
- C. Cytokinin
- D. Carbon dioxide
Q26. Which is part of the body's first line of non-specific defence?
- A. Cytotoxic T cells
- B. Memory B cells
- C. Lysozyme in tears and saliva
- D. Antibodies from plasma cells
Q27. At a site of infection, the area becomes red, warm and swollen. This is mainly caused by:
- A. Red blood cells bursting
- B. Antibodies blocking blood flow
- C. Histamine released from mast cells dilating blood vessels and increasing permeability
- D. Insulin acting on the skin
Q28. Helper T cells do not kill infected cells themselves, yet their loss severely weakens immunity because they:
- A. Form the skin barrier
- B. Produce antibodies directly
- C. Engulf and digest bacteria
- D. Release cytokines that activate B cells and cytotoxic T cells
Q29. An antibody (IgG) molecule is made of:
- A. Four identical light chains
- B. Two heavy chains with no light chains
- C. One heavy chain only
- D. Two heavy and two light polypeptide chains joined by disulphide bonds
Q30. A person bitten by a snake is given antivenom (antibodies raised in a horse). Which statement about this treatment is correct?
- A. It works only after two weeks
- B. It gives long-lasting active immunity
- C. It gives immediate but short-lived passive immunity
- D. It stimulates memory cells against the venom