IB Biology SL C2.2 Neural Signalling Questions

Practise IB Biology SL C2.2 by linking neuron structure, resting potential, myelin and impulse conduction to exam evidence.

Exam points

Label neuron structures and distinguish sensory, relay and motor neuron roles, directions and connections.
Define resting potential, read its approximate negative voltage, and explain the ATP-driven pump moving 3 Na⁺ out for 2 K⁺ in.
Trace nerve impulses through threshold, Na⁺ influx/depolarization and K⁺ efflux/repolarization, using membrane-potential diagrams.
Relate axon diameter and myelin sheath to faster impulse transmission and saltatory conduction.
Distinguish presynaptic release sites from postsynaptic receptors and explain how the narrow cleft supports rapid diffusion.
Explain one-way synaptic transmission from action-potential/Ca²⁺-triggered vesicle release through cleft diffusion to postsynaptic receptor activation.
Explain how neurotransmitter binding opens postsynaptic ion channels to generate an EPSP and make threshold more likely.

Covered syllabus points

C2.2.1—Neurons C2.2.2—Resting potential generation C2.2.3—Nerve impulses as action potentials C2.2.4—Variation in impulse speed C2.2.5—Synapses as junctions C2.2.6—Neurotransmitter release C2.2.7—Excitatory postsynaptic potential

[Maximum number: 6]

The diagram below shows a motor neuron.

(a)

Label the structures indicated by the numbers I-IV.

[ 2 ]

(b)

Define resting potential.

[ 1 ]

(c)

Outline how nerve impulses are transmitted along a nerve fibre.

[ 3 ]

a. (sodium channels/voltage-gated channels open and) $\mathrm{Na}^{+}$ diffuse into neuron (down concentration gradient);
b. inside of neuron becomes positive compared to outside / potential is reversed / depolarization;
c. wave of depolarization moves (down the membrane);
d. (potassium channels open and) $\mathrm{K}^{+}$ diffuse out (down concentration gradient);
e. inside becomes negative compared with outside / potential across membrane restored / repolarization;
f. active transport of $\mathrm{K}^{+}$ (into neuron) and $\mathrm{Na}^{+}$ (out of neuron) restores resting potential;

All question bank results loaded

I	nucleus/cell body/soma
II	myelin sheath/Schwann cell
III	axon
IV	dendrites

Covered syllabus points

Question 1

Question (a)

Question (b)

Question (c)