Question 19N.3.HL.TZ0.4
| Date | November 2019 | Marks available | [Maximum mark: 6] | Reference code | 19N.3.HL.TZ0.4 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Explain, Identify, Outline, State | Question number | 4 | Adapted from | N/A |
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. 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 ✔
Outline the main feature of neural pruning.
[1]
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".
State the name of the part of the brain that controls breathing rate.
[1]
medulla «oblongata» ✔ Do not accept "brain stem".
Explain the need for the adult human brain to be supplied continuously with a relatively large supply of blood.
[3]
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
