IB Biology HL (HIGHER level)- 2024 – Practice Questions- All Topics
Topic 6.5 Neurons and synapses
Topic 6 Weightage : 20%
All Questions for Topic 6.5 – Neurons, Resting Potential, Action Potential, Nerve Impulses, Oscilloscope Traces, Myelination, Synaptic Transfer, Neurotransmitters, Graded Potentials, Nervous System, Stimulus-Response, Reflex Actions, Summation, Types of Neurotransmitters
Question
Which structural feature enables saltatory conduction?
A Nodes of Ranvier between Schwann cells
B Na+ channels under Schwann cells
C K+ channels under Schwann cells
D Sodium–potassium pumps under Schwann cells
▶️Answer/Explanation
Ans: A
Question
Which statement applies to an axon at rest?
A There is no electric potential difference between the external and internal surfaces of the plasma membrane.
B The external surface of the plasma membrane is positive relative to the internal surface.
C The external surface of the plasma membrane is negative relative to the internal surface.
D The internal surface of the plasma membrane has a much higher concentration of sodium ions.
▶️Answer/Explanation
Ans: B
Question
An individual was presented with a stimulus resulting in the release of epinephrine. What was the most likely nature of the stimulus?
A Sunset and the onset of darkness
B An image of a close friend
C The intake of glucose
D A coach shouting to begin physical activity
▶️Answer/Explanation
Ans: D
What happens when an action potential reaches motor end plates?
A. Calcium ions are absorbed by the muscle fibres.
B. The sarcomeres relax.
C. Neurotransmitter is released.
D. Action potential is passed to the neuron.
▶️Answer/Explanation
Markscheme
C
The decline in European honeybee (Apis mellifera) populations may be linked to neonicotinoid pesticides. What effect do these pesticides have on the nervous system of insects?
A. They prevent acetylcholinesterase from breaking down acetylcholine.
B. They inhibit depolarization in the presynaptic neuron which increases the levels of acetylcholine.
C. They produce an inhibitor that promotes the binding of acetylcholine.
D. They block synaptic transmission by binding with postsynaptic acetylcholine receptors.
▶️Answer/Explanation
Markscheme
D
What is the mechanism of sodium-potassium pumps in neurons that generates a resting potential by active transport?
A. K+ from cytoplasm binds to the pump and stimulates its phosphorylation by ATP.
B. Phosphorylation of the pump causes its shape change in order to move Na+ into the cytoplasm.
C. K+ from inside the cell binds to the pump and causes the release of the phosphate group.
D. Na+ from cytoplasm binds to the pump and stimulates its phosphorylation by ATP.
▶️Answer/Explanation
Markscheme
D
What is a feature of neurons?
A. Relay neurons transmit impulses from motor to sensory neurons.
B. The cell body of a motor neuron is in the CNS.
C. Sensory neurons carry impulses away from the CNS.
D. Relay neurons form synapses with receptors.
▶️Answer/Explanation
Markscheme
B
Question
Atropine drops are used by opticians to dilate the pupil, so that a thorough examination of the retina can be performed. Atropine binds to acetylcholine receptors in synapses.
What is the effect of atropine binding in synapses?
A. Inhibits the binding of acetylcholine at the presynaptic membrane
B. Inhibits the release of acetylcholine from the presynaptic neuron
C. Prevents binding of acetylcholine at the postsynaptic membrane
D. Prevents transport of acetylcholine through the postsynaptic membrane
▶️Answer/Explanation
Ans:C