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

Question

The figures below show a human and a sheep brain.

[Source: Pearson Scott Foresman, donated to the Wikimedia Foundation,
https://commons.wikimedia.org/wiki/File:Convolution_he_-_sheep_and_human_brain.png]

The human brain is larger than the brain of many animals. Identify one other difference between the human brain and the brain of a sheep.

[1]
a.

Outline the main feature of neural pruning.

[1]
b.

State the name of the part of the brain that controls breathing rate.

[1]
c.

Explain the need for the adult human brain to be supplied continuously with a relatively large supply of blood.

[3]
d.

Markscheme

a. larger cerebral cortex in human brain ✔ Do not accept larger brain for human as it is in the stem.

b. higher folding in human brain
OR
increased surface area in human brain ✔

c. angle of spinal cord more vertical in human
OR
angle of spinal cord more horizontal in sheep ✔

a.

a. loss of unused neurons ✔ Accept apoptosis or programmed neuron death.

b. loss of unused synapses
OR
reducing the number of synapses
OR
leaving more efficient synaptic configurations ✔ Do not accept "connection" instead of "synapse".

b.

medulla «oblongata» ✔ Do not accept "brain stem".

c.

a. the brain contains a very large number of neurons and therefore consumes large amount of energy ✔ OWTTE

b. «large» requirement for oxygen/glucose to provide energy for «aerobic» cell respiration ✔

c. energy used to sustain the electric charges of neurons
OR
energy used to sustain the membrane potential of neurons
OR
energy used to produce neurotransmitters ✔

d. brain has continuous activity that requires continuous supply of oxygen/glucose ✔ OWTTE

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.2 The human brain
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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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