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Date November 2019 Marks available 1 Reference code 19N.3.SL.TZ0.4
Level Standard level Paper Paper 3 Time zone TZ0 / no time zone
Command term State Question number 4 Adapted from N/A

Question

The development of the neural tube in the frog Xenopus is shown in the diagram.

[Source: reprinted by permission from Nature Reviews Neuroscience, Gammill, L., Bronner-Fraser, M.
Neural crest specification: migrating into genomics. Nat Rev Neurosci 4, 795–805 (2003) doi:10.1038/nrn1219]

State the name of the stage of embryonic development shown in the diagram.

[1]
a.

Identify the part labelled X.

[1]
b.

State a consequence of incomplete folding of the neural tube in humans.

[1]
c.

Explain how the nervous system develops from the cells of the neural tube.

[2]
d.

Markscheme

neurulation ✔

a.

neural plate
OR
neural groove
OR
ectoderm ✔

b.

spina bifida ✔

Accept a description of spina bifida

c.

a. neurons differentiate from neural tube / stem cells ✔

b. axons/dendrites grow ✔

c. «axon growth is» directed by chemicals/growth substances ✔

d. neurons migrate ✔

e. synapses form ✔

d.

Examiners report

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

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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