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 | State | 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.
Outline the main feature of neural pruning.
State the name of the part of the brain that controls breathing rate.
Explain the need for the adult human brain to be supplied continuously with a relatively large supply of blood.
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. 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".
medulla «oblongata» ✔ Do not accept "brain stem".
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