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Date May 2018 Marks available 2 Reference code 18M.3.HL.TZ2.4
Level Higher level Paper Paper 3 Time zone Time zone 2
Command term Outline Question number 4 Adapted from N/A

Question

Modification of neurons starts in the earliest stages of embryo development and continues to the final years of life. The image shows changes occurring in mice brain neurons at an early stage in life.

Outline how an immature neuron develops an axon.

[2]
a.

Explain neuroplasticity in terms of the developing neurons.

[3]
b.

Markscheme

a. neurons initially produce multiple dendrites/prolongations 

b. an axon develops in response to chemical stimuli

a.

a. neurons that are stimulated develop more dendrites «than those not stimulated» 

b. more dendrites allow for more synapses 

c. developing neurons form multiple/new synapses 

d. synapses that are stimulated/used many times are fortified 

e. neural pruning involves the loss of unused neurons/synapses 

f. plasticity of the nervous system allows it to change with environment/experience/to reorganize following damage
OR
some neurons can regenerate

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Option A: Neurobiology and behaviour » Option A: Neurobiology and behaviour (Core topics) » A.1 Neural development
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Option A: Neurobiology and behaviour » Option A: Neurobiology and behaviour (Core topics)
Option A: Neurobiology and behaviour

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