IB Biology HL C2.2 Neural Signalling Questions

Practise IB Biology HL C2.2 with membrane-potential traces and synapse data covering action potentials, neurotransmitters, saltatory conduction, summation and drugs.

Exam points

Label neuron structures and distinguish motor and sensory neuron arrangements and connections.
Define resting potential and explain how the ATP-driven sodium-potassium pump maintains 3 Na⁺-out/2 K⁺-in gradients and axon polarization.
Explain action-potential initiation through threshold and all-or-none response, voltage-gated Na⁺ influx/depolarization, delayed K⁺ efflux and repolarization or hyperpolarization.
Interpret action-potential traces and oscilloscope output using threshold, ion movement and channel timing, including membrane-potential change calculations.
Calculate and compare conduction speeds using axon-diameter and myelin data.
Explain how local Na⁺ currents depolarize the next axon region to threshold during propagation.
Identify nodes of Ranvier and myelin, then explain node-to-node saltatory conduction and speed.
Explain one-way synaptic transmission using acetylcholine receptor binding, breakdown and postsynaptic effects.
Explain how an arriving action potential opens Ca²⁺ channels, fuses vesicles and releases neurotransmitter.
Explain EPSP receptor binding and postsynaptic ion flow that causes depolarization.
Explain how exogenous chemicals alter synaptic transmission by mimicking, blocking or prolonging neurotransmitter effects.
Distinguish excitatory and inhibitory inputs and explain temporal/spatial summation reaching threshold.
Interpret fMRI scans to compare activation patterns and motor function after stroke.

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 C2.2.8 (HL)—Depolarization and repolarization C2.2.9 (HL)—Action potential propagation C2.2.10 (HL)—Oscilloscope traces C2.2.11 (HL)—Saltatory conduction C2.2.12 (HL)—Exogenous chemicals C2.2.13 (HL)—Inhibitory neurotransmitters C2.2.14 (HL)—Summation C2.2.15 (HL)—Pain perception C2.2.16 (HL)—Consciousness

[Maximum number: 12]

(a)

Draw a labeled diagram to show the structure of a motor neuron.

[ 4 ]

(b)

Explain how nerve impulses pass from one neuron to another neuron.

[ 8 ]

[Maximum number: 4]

Outline how neurons generate a resting potential.

a	sodium-potassium pump
b	sodium $/ \mathrm{Na}^{+}$ out and potassium $/ \mathrm{K}^{+}$ in OR sodium $/ \mathrm{Na}^{+}$ concentration higher outside and potassium $/ \mathrm{K}^{+}$ higher inside
c	three $\mathrm{Na}^{+}$ pumped for every two $\mathrm{K}^{+}$ (hence negative inside) OR inside of axon holds negative ions/ $\mathrm{Cl}^{-}$ ions/negatively charged proteins/organic anions (hence negative inside)
d	by active transport / using ATP
e	inside (of axon/neuron) is negative in comparison to outside OR electrochemical concentration/charge difference (across the membrane) is the resting potential
f	resting potential is -70 mV

[Maximum number: 1]

Neurons transmit electrical impulses. Which statement describes part of this process?

$\mathrm{K}^{+}$ ions are pumped out of the cell to depolarize the membrane.

Ion channels let $\mathrm{K}^{+}$ diffuse into the cell to depolarize the membrane.

$\mathrm{Na}^{+}$ ions are pumped into the cell to repolarize the membrane.

Ion channels let $\mathrm{Na}^{+}$ diffuse into the cell to depolarize the membrane.

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Covered syllabus points

Question 1

Question (a)

Question (b)

Question 2

Question 3