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Date November 2016 Marks available 2 Reference code 16N.3.SL.TZ0.5
Level Standard level Paper Paper 3 Time zone TZ0 / no time zone
Command term Outline Question number 5 Adapted from N/A

Question

The diagram shows the early development of the nervous system in embryonic chordates.

Outline the process taking place in the diagram.

[2]
a.

State what occurs to structure X immediately following its formation.

[1]
b.

Outline how spina bifida could occur during embryonic development.

[1]
c.

Markscheme

a. infolding of the ectoderm /neural plate

“Ectoderm” is essential for the mark.

b. formation of the neural tube
OR
neurulation

“Neural tube” or “neurulation” is essential for the mark.

 

 

 

 

a.

elongation / forms a tube

 

 

 

b.

a. neural tube/structure X does not close properly

b. folic acid/folacin/folate/vitamin B9 deficiency

c. may be due to mutation / genetic condition

 

 

 

c.

Examiners report

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

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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