Home / IB DP Biology- C2.2 Neural signaling- IB Style Questions For HL Paper 1A

IB DP Biology- C2.2 Neural signaling- IB Style Questions For HL Paper 1A -New Syllabus

IBDP Biology HL Paper 1 - All Chapters

Question

The table shows two types of gated ion channels in neurons. How are they gated?

 Nicotinic acetylcholine receptorsPotassium channels
AVoltageNeurotransmitter
BNeurotransmitterVoltage
CVoltageVoltage
DNeurotransmitterNeurotransmitter
▶️ Answer/Explanation

Correct Answer: \( \boxed{\mathbf{B}} \)

Nicotinic acetylcholine receptors are ligand-gated (neurotransmitter-gated) channels that open when acetylcholine binds to them. In contrast, potassium channels involved in nerve impulses are voltage-gated, opening in response to changes in the membrane potential during an action potential.

Question

The image shows a neuron. Which letter shows a dendrite?

▶️ Answer/Explanation

Correct Answer: \( \boxed{\mathbf{A}} \)

Dendrites are short, highly branched extensions that receive nerve impulses from other neurons and transmit them towards the cell body. In the diagram, label A indicates these branched projections, identifying it as the dendrite.

Question

The graph below represents changes in membrane potential during an action potential in a neuron.

During which phase on the graph do voltage-gated sodium channels open, leading to rapid depolarization of the neuron’s membrane?

A. At \( 1 \)
B. Between \( 1 \) and \( 2 \)
C. At \( 2 \)
D. Between \( 2 \) and \( 3 \)

▶️ Answer/Explanation

Voltage-gated sodium (\(\text{Na}^+\)) channels open at the start of depolarization, allowing sodium ions to flow rapidly into the neuron.

This occurs between points \( 1 \) and \( 2 \) on the graph, where the membrane potential rises sharply from its resting potential of approximately \( -70~\text{mV} \) toward positive values, peaking around \( +40~\text{mV} \).

✅ Answer: (B) Between \( 1 \) and \( 2 \)

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