Human speech occurs at a volume of approximately 60 dB and at frequencies between 125 Hz and 4000 Hz. Outline whether the woman would hear all conversations with both ears.

The woman suffers from otosclerosis in the right ear, a condition where the bones of the middle ear do not function properly. Describe how this is consistent with the hearing test result shown in the audiogram.

Explain the role of the hair cells in the cochlea.

left ear would hear everything but the right ear would not «at higher frequencies»
OR
cannot hear all high frequencies of speech (with both ears)

Allow numerical responses in support of the answer.

a. the bones in the middle ear amplify/make sounds louder

b. the audiogram shows the woman needs louder sounds to hear with her right ear

Allow vice versa.
Could use data to support answer.

a. sounds/vibrations make the fluid/liquid in the cochlea move/vibrate

b. amount of movement is proportional to the amplitude /loudness/ of the sound  OWTTE.

c. amount of movement is proportional to the frequency/wavelength/pitch

d. hair cells located within organ of Corti

e. (hair cells have) nerve cells connected to auditory nerve
OR
nerve cells transmit impulses to brain

Outline the process taking place in the diagram.

State what occurs to structure X immediately following its formation.

Outline how spina bifida could occur during embryonic development.

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.

elongation / forms a tube

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

(i) Identify the structure labelled X.

(ii) Outline the function of X in the human brain

With reference to structures visible in the diagrams, explain how the human brain is more evolved for higher order functions than the baboon brain.

(i) cerebellum

(ii)

a. coordinates the actions of muscles
OR
motor control

b. important in balance/movement/muscle tone/posture

Do not allow ECF.

a. «higher order functions are» controlled by the cerebral hemispheres

b. the human brain has more folding of the (cerebral) cortex than the baboon brain

c. «folding» allows for more surface area / more synapses

d. «more cerebral cortex» without increasing cranium size

e. frontal lobe is larger proportion in the human brain than in the baboon brain

Do not allow answers relating to size as diagrams are not to scale and size is not “visible”.

Do not accept cerebellum unless a higher order function is given.

Identify the structures labelled I and II

Explain how the pupil of the eye can be used to assess brain damage.

I: conjunctiva/sclera
AND
II: iris/cornea

To award [1] both answers are needed.

a. bright lights causes the pupil to constrict/iris to increase in size

b. low light causes the pupil to dilate/iris decrease in size

c. these are reflex actions

d. the test for brain damage is to (briefly) shine a bright light in the eyes

e. slow or unresponsive change in pupil size indicates brain damage/concussion

f. different response of each eye indicates brain damage/concussion

State the name of the photoreceptor shown.

Distinguish between a photoreceptor and an olfactory receptor.

rod

In a study of brain organization, several factors were investigated. The relationship between the volumes of grey and white matter across mammalian species was compared.

Describe the relationship between the volume of white matter and grey matter.

Outline the organization of the human cerebral cortex with regard to structure and function.

Outline one reason for the large energy requirement of the brain.

a. positive correlation «between grey matter volume and white matter volume»
OR
as white matter «volume» increases so does grey matter «volume» 

b. As animal/brain size increase the volume of grey and white matter are «approaching» equal
OR
as volume of grey matter increases, the ratio grey : white becomes closer to 1

Structure:

a. divided into left and right hemisphere 

b. has extensive folding 

c. has a large surface area : volume ratio

Function:

d. responsible for higher order functions/thinking/learning/memory/language 

e. functions are located in specific areas of the cortex/lobes 

f. sensory/motor functions of the left hemisphere correspond to the right side of the body

a. «brain» cells/neurons carry out large amount of respiration/metabolic activity 

b. maintenance of resting potential requires energy/ATP
OR
functioning of Na-K pumps requires energy/ATP
OR
nerve impulse requires energy/ATP

The diagram shows the anatomy of the human ear.

Label the cochlea on the diagram.

Explain the structure of the semicircular canals in relation to their functions.

Explain the role of ganglion cells in the eye.

a. there are three semi-circular canals set perpendicular to one another /orientated in three planes of space / the direction of movement of the head in any direction is sensed 

b. each canal is filled with liquid/perilymph 

c. each canal contains «sensory» hairs 

d. when the head moves the liquid in the canal moves more slowly/lags behind 

e. this causes the sensory hairs to bend 

f. send impulses to the brain «via the vestibular nerve»

a. ganglion cells transfer information to the brain 

b. they receive visual information from photoreceptors/rod and cone cells/bipolar cells 

c. their long axon extends to the brain «in the optic nerve» 

d. they detect/process movement/colour

Calculate the rate of movement of the neuron cell body between 0 and 5 h. Working should be shown, giving the units.

Suggest a reason for the migration of neurons in the embryonic nervous system.

Outline neural pruning.

a. cell moves 25−28mm
OR
71−93μm 

b. speed range is 71−93 μm in 5 hours 

c. answer in the range 14−19 μm/h or μm h⁻¹

a. «neural migration» positions cell types from different origins into specific locations 

b. «neural migration» allows formation of connections/synapses 

c. allows for differentiation of cell types/types of neuron

a. neural pruning is the removal of synapses/dendrites/ neural connections 

b. caused by lack of use 

c. it occurs during brain development/between birth and end of puberty 

d. allows new neural connections/makes nervous system more efficient /plasticity 

Label the parts I and II on the images.

Structure Y will eventually elongate to form two structures. State the names of these two structures.

1.

2.

State the condition that arises if the closure of structure X is incomplete during embryonic development.

I: neural groove/plate/fold 

II: ectoderm

brain 

spinal cord

spina bifida

The cortex of the brain consists of several regions.

State whether this view of the brain shows the left side or the right side.

Outline the function of Broca’s area.

left «side»

a. speech production 

b. language comprehension/processing 

c. damage leads to difficulty in verbalising thoughts

Outline the effect of the cochlear implant on hearing.

Suggest, with reference to the structure of the ear, a reason that a cochlear implant requires an amplifier.

Describe the normal function of the cochlea.

a. the implant lowered the threshold of hearing
OR
allowed quieter sounds to be heard;

b. the person would be able to hear human speech;

the implant is not connected to the bones (whose function is to amplify sound)
OR
the implant bypasses the middle ear
OR
the amplifier replaces the function of the bones

a. vibrations cause fluid in the cochlea to move;

b. (movement of fluid) causes stimulation/movement of haircells/mechanoreceptors;

c. higher frequency is detected closer to the base of the cochlea / vice versa
OR
each frequency stimulates specific hair cells;

d. hair cells generate impulses;

e. connected to the brain by the auditory nerve;

Many candidates correctly stated that the cochlear implant lowered the hearing threshold, but fewer stated it would allow human speech to be heard.

The need for an amplifier as the bones of the middle ear were bypassed was noted by the stronger candidates.

Candidates get confused when describing the function of the cochlea. Most know there is fluid and there are hair cells, but answers were often confused. Only the better candidates stated that hair cells respond to different frequencies of sound.

Explain how autopsy and lesions can be used to identify the role of different brain parts.

a. an autopsy occurs after death/post-mortem;

b. lesions occur in the brain because of injury/illness;

c. changes in function/behaviour can be attributed to damaged areas;

d. can be diagnosed using fMRI/CAT scan/PET scan;

e. one example e.g. damage to Broca’s area affects speech;

This question discriminated well, with strong candidates scoring full marks. There were marks awarded for simply stating what is meant by autopsy and lesions, but many weaker candidates failed to do this. A few referred to animal experimentation or removing parts of brain in live humans to see the effect.

Draw a ray of light entering the left eye from point P. 

Information about the light from P entering the left eye is processed in the brain.

State what region of the brain would process the information.

Information about the light from P entering the left eye is processed in the brain.

State the side of the brain that would process the information.

State the type of cell in the retina which directly transmits impulses through the optic nerve to the brain.

Any straight line from P passing through the lens to the retina of left eye.

visual cortex/occipital lobe;

right;

ganglion (cell);

This question on the eye was well answered though there was some confusion between ganglion and bipolar cells.

Identify the structure labelled A.

List two functions of the structure labelled A.

Outline the reason that Broca’s area is more developed in humans than other primates.

Suggest how an injury to the brain can help in understanding brain function.

medulla «oblongata»

OR

brain stem

a. breathing «rate»

b. heart function

c. digestion/saliva production

d. swallowing reflex

e. coughing

f. vomiting

g. blood pressure

h. state of consciousness/sleep

Allow any two functions.

No ECF

[Max 2 Marks]

«controls motor functions involved with speech and» speech is more developed in humans

observe any changes in the person

Identify the cell labelled X.

Draw an arrow to show the direction of light through the retina.

bipolar «cell»

arrow pointing from right to left

Using the letter M, label the structures which detect movement of the head.

Using the letter A, label where sound is amplified.

Explain the function of the cochlea in hearing.

Outline how the hearing of a deaf or partially deaf person could be improved.

Example of answer for part (a)(i)

The candidate should label the semicircular canals

Line with the letter M is expected but accept the letter M on diagram if clearly indicating the correct structure

Example of answer for part (a)(ii)

The candidate should label the bones/ossicles in middle ear

Line with the letter A is expected but accept the letter A on diagram if clearly indicating the correct location

a. sound «waves» enters the ear causing fluid in the cochlea to move/vibrate

b. «movement of fluid in cochlea» causes the hair cells to move

c. «details of hair cell movement» is transmitted to brain via the auditory nerve

[Max 2 Marks]

hearing aid/cochlear implant

Answer must refer to ear, not for example just “operation”

Accept other valid answers

The metabolic rate is the energy used per kilogram of mass per day. Calculate the metabolic rate of the brain.

Using only the data in the table, distinguish between the use of energy in the brain and in skeletal muscle.

Suggest one reason for the difference between the brain and skeletal muscle in metabolic rate.

Outline the role of the brain in involuntary control.

1000 ✔

Working not required

a. skeletal muscle uses more total energy than the brain ✔

b. the brain uses more energy per kg than skeletal muscle
OR
the brain has higher metabolic rate ✔

Accept numerical answers if comparative terms are used

a. «brain requires more» energy to maintain a proper ionic balance/homeostasis/active transport ✔

b. «brain requires more» energy for synapses/neurotransmitters ✔

c. «brain requires more» energy for thinking and memory ✔

d. skeletal muscle active on demand but brain constantly active ✔

a. does not require conscious thought ✔

b. can respond to emergency situation and «actively» return the body to normal ✔

c. medulla/brain stem controls involuntary activities ✔

d. eg: swallowing/breathing/heart rate ✔

Accept other valid examples

Describe the process taking place.

Outline the possible changes to this neuron that could happen during the subsequent development of the nervous system.

Suggest how the plasticity of the brain can benefit humans.

a. «the process shows» the growth of an axon/dendrites/extensions ✔

b. differentiation/forming a specialized neuron ✔

c. responding to a chemical stimulus ✔

a. the neuron forms synapses/multiple connections «with other neurons»
OR
a neural network forms
OR
more dendrites ✔

b. some synapses/connections in excess of what is required
OR
some synapses/connections not used ✔

c. it could be removed by neural pruning/apoptosis ✔

d. it could migrate to another place ✔

a. allows brain to change/adjust/make new synapses throughout lifetime/with experience/learning ✔

b. allows regeneration of neurons after brain trauma
OR
allows other area «of the brain» to take over a function after brain trauma ✔ 

c. selective advantage/increases chance of survival ✔

OWTTE

Identify the structure labelled X.

Explain how sound from an outside source causes movement of the hair cells in the cochlea.

pinna/auricle ✔

a. sound travels in «longitudinal» waves/vibrations ✔

b. vibrations in the air cause vibration of the eardrum ✔

c. the vibrations/sounds are passed on to the bones/ossicles «of the middle ear» ✔

d. the bones amplify the sound/vibrations ✔

e. «bones» transmit sound/vibrations to the oval window ✔

f. vibration of oval window causes fluid movement in the cochlea «in the inner ear» ✔

g. hair cells move with the vibrations/sound ✔

On the diagram, label the visual cortex.

Identify the structure labelled X.

Explain how a functional MRI (fMRI) can be used to identify the function of parts of the brain.

Accept any label within the area shown on the image

pituitary gland ✔

a. magnetic field is used to make pictures of brain/organs/structures ✔

b. an fMRI shows changes in blood flow ✔

c. increased blood flow associated with activity in specific areas of the brain ✔

d. performance of task matched with active area of brain ✔

Label the pupil and the retina on the diagram.

[Source: Holly Fischer https://en.wikipedia.org/wiki/Human_eye#/media/File:Three_Internal_chambers_of_the_Eye.png]

Explain the use of the pupil reflex as a test for brain damage.

State the property of the nervous system that allows it to change with experience and allows the brain to recover from a stroke.

retina

pupil

e.g: 

[Source: Holly Fischer https://en.wikipedia.org/wiki/Human_eye#/media/File:Three_Internal_chambers_of_the_Eye.png]

a. «bright» light is shone in to the eye 

b. the pupil reflex is when the pupils constrict 

c. if not observed could indicate damage to the optic nerve/ocular motor nerve/medulla oblongata
OR
brain stem death
OR
depressant drug use

plasticity

Explain the stages of development and differentiation of neurons.

a. development of neurons occurs in the neural tube/plate 

b. produces large numbers of cells that differentiate into neurons 

c. some neurons migrate 

d. axons grow out from the immature neuron 

e. in response to chemical stimuli 

f. neurons synapse/form connections with «multiple» other neurons 

g. some neurons removed by neural pruning

Identify the part of the ear labelled X.

Compare and contrast the mechanisms involved in hearing sounds in individuals with and without cochlear implants.

Outline the role of the ear in balance perception.

semicircular canal(s)

Compare:

a. sound transmitted by the auditory nerve in both cases
OR
both change sound waves to electrical impulses 

Contrast:

b. without CI cochlea stimulated by vibrations/middle ear bones whereas with CI electrical signals stimulate cochlea
OR
with a CI the auditory nerve is stimulated by electrodes whereas without CI the auditory nerve is stimulated by hair cells

One compare and one contrast must be given.

a. head movements cause fluid in the canals to move 

b. this deflects hair cells 

c. (semicircular canals) are perpendicular/right angles detecting movements in any direction/plane 

d. send nerve impulses to the brain (by acoustic nerve)

Explain how information from the left and right sides of the visual field is processed.

a. information from the left-half of the visual field is detected by the right-half of the retina
OR
information from the right-half of the visual field is detected by the left-half of the retina 

b. information from left-half of visual field is processed by the right hemisphere
OR
information from right-half of visual field is processed by the left hemisphere 

c. impulses travel through optic nerve 

d. optic nerves from each eye meet at the «optic» chiasma 

e. information from inner fields «closer to the nose» cross at the «optic» chiasma  OWTTE

f. impulses continue to the brain 

g. an image forms in the visual cortex

Accept answer in a clearly annotated diagram.

Outline the function of one named photoreceptor in the mammalian eye.

Explain how neurons at rest still consume energy.

Identify the species with photoreceptors that have the fastest signalling transmission rate.

Describe the relationship between energy consumption and transmission rate.

a. name: rod
OR
cone 

b. function: rod detects wide range of wavelengths/monochrome/low light intensity/dim light
OR
detects coloured light / colour «photoreceptor»

a. maintenance metabolism/respiration of the neuron 

b. use of Na-K/sodium potassium pump to maintain resting potential 

c. cell repair «consumes energy»

S. carnaria / Sarcophaga carnaria

a. energy consumption increases from rest to signalling «in all three species» 

b. faster transmission consumes more energy
OR
positive correlation 

c. doubling of transmission rate requires more than double the increase in energy consumption
OR
exponential increase
OR
the higher the energy consumption at rest, the higher the energy consumption at signalling

Explain the neural control of swallowing.

Neurons are initially produced by differentiation in the neural tube. Outline the mechanisms of axon and synapse development that follow the initial creation of neurons.

a. voluntary passage of food through the mouth ✔

b. «bolus of» food touches the walls of the pharynx ✔

c. nerve sends message/impulse to brain ✔

d. swallowing centre in the medulla «oblongata» ✔

e. now involuntary/unconscious/autonomic responses/reflexes ✔

f. triggers closing of epiglottis «to prevent choking» ✔

g. leading to contraction of muscles/peristalsis «in the pharynx and esophagus» ✔

a. axons are extensions of the neuron cell body ✔ 

b. some axons grow out of the neural tube and connect to other parts of the developing embryo ✔

c. chemical stimuli affect axon growth ✔

d. more dendrites form ✔

e. axon reaches the target cell ✔

f. forms single/multiple synapse«s» ✔

g. neural pruning involves the loss of neurons/synapses ✔

Do not accept migration of neurons

Very few candidates recognized the voluntary aspect of swallowing. The role of the medulla and consequent involuntary action were most often described, although answers were frequently quite muddled.

The question was often not read properly, with answers describing formation and migration of neurons, and chronological steps were rarely seen. Most answers receiving credit involved synapse formation and neural pruning.

State the name of the general area of the brain affected by this stroke.

Explain how patient recovery from a stroke illustrates the property of neural plasticity.

Explain how studies of lesions have helped to identify the functions of different parts of the brain.

cerebrum/cerebral hemisphere/cerebral cortex ✔

a. «neural plasticity» is the ability to form new neural connections/synapses ✔

b. the area that is damaged by the stroke had a specific function ✔ 

c. other area of the brain can take on these functions ✔

a. lesions are areas of brain injury ✔

b. diagnosed in living people using fMRI/CAT scan/PET scan ✔

c. autopsies reveal the position and extent of lesions/animal experimentation ✔

d. the behaviour/functioning of patient with lesion was observed ✔

Specific areas (some incorrect) were often given rather than general and “cerebral” was often omitted.

The concept of neural plasticity was generally understood but not that new connections are made in areas other than that damaged by a stroke.

Autopsies were more often mentioned than fMRIs. The link between position of a lesion and lost function was well understood.

State the name of the technique used to produce the image.

Identify the area of the brain responsible for processing visual stimuli.

Identify the area of the brain labelled X in the image.

fMRI / functional MRI

f or functional required.

visual cortex / occipital lobe

hemisphere

Outline the relationship between the distance from the oval window and the sound frequency detected.

State the range of sound frequencies detected by the ear.

Sensory receptors are divided into different categories. Hair cells in the cochlea are sensory receptors. State the category to which they belong.

Identify the structure labelled Y in the diagram.

Annotate the diagram with an X to show the internal location where a cochlear implant is placed.

Outline the function of the stapes.

the further from the base, the lower the frequency detected ✔

Allow vice versa

20 000 Hz «20 kHz» to 20 Hz ✔

Unit required. Allow 19 980 Hz.

mechanoreceptor ✔

auditory/cochlear/acoustic nerve ✔

cochlea annotated with an X ✔

eg:

[Source: Didier Descouens, https://commons.wikimedia.org/wiki/Category:Human_middle_ear#/media/File:Place-desosselets-
Schema.jpg, licensed under CC BY-SA 3.0]

X can be anywhere in the spiral of the cochlea

a. connects the oval window to the eardrum/ossicles ✔

b. mechanical transmission of vibration of eardrum
OR
amplify vibration/sound ✔

c. moves oval window with frequency of the vibration/sound
OR
transmits vibration/sound to inner ear/cochlea ✔

Most answered correctly.

The correct frequency range was given but the unit was often omitted.

Perhaps a third of candidates gave the correct term.

Most correct answers were for auditory nerve rather than the alternatives.

Most candidates placed the X in the correct region.

There were some good answers here, although connections to parts of the ear were sometimes confused. Amplification and transmission to the cochlear were frequent responses

The diagrams illustrate changes in synapse density of the cerebral cortex from newborn to adult.

[Source: THE POSTNATAL DEVELOPMENT OF THE HUMAN CEREBRAL CORTEX, VOLUMES IVIII, by Jesse LeRoy Conel, Cambridge, Mass.: Harvard University Press, Copyright © 1939, 1941, 1947, 1951, 1955, 1959, 1963, 1967
by the President and Fellows of Harvard College. Copyright © renewed 1967, 1969, 1975, 1979, 1983, 1987, 1991.]

Explain the processes illustrated by the diagrams.

a. at birth neurons are mainly unconnected

b. after birth «up to 2 years» neurons start to make synapses/connections with other neurons

    OR

    up to 2 years the number of synapses/connections increases

c. «increase in synapses» occurs rapidly due to learning/new experiences

d. each neuron can make multiple synapses

e. brain makes many more connections than are required

f. «after 2 years/in adults» neural pruning causes the loss of unused neurons/synapses/connections

Do not accept more neurons are made

[Max 4 Marks]

State the trend in relative brain mass in primates other than humans according to their time of divergence from humans.

Suggest one reason that the relative brain mass of Homo is different from Parapithecus and Australopithecus.

Deduce, with a reason, whether the relative brain mass is a good indicator of brain development.

Primates belong to the phylum chordata. The neural tube of chordates is formed by the infolding of the ectoderm followed by the elongation of the tube. Outline the process of formation of neurons from this neural tube in primates.

the longer ago they diverged from humans, the greater the relative brain mass ✔

Accept inverse.

Do not accept negative correlation.

a. human cerebral cortex has extensive folding producing a greater mass ✔

b. better diet/more protein allowed increase in «relative» brain mass in humans ✔

c. others had larger body to protect them from predators «without increase in brain mass» ✔

a. not a good indicator because it depends on body mass ✔

b. not a good indicator as less developed organisms show a larger relative brain mass ✔

Accept answers referring to specific organisms shown

a. neurons formed by a process called neurulation ✔

b. neurons are «initially» produced by differentiation «in the neural tube» ✔

c. immature neurons migrate to a final location ✔

d. an axon grows from each immature neuron in response to chemical stimuli ✔

e. some axons extend beyond the neural tube to reach other parts of the body ✔

f. a developing neuron forms multiple synapses ✔

This question concerned how relative brain mass varied in primate evolution. Overall it was not well answered. The decreasing scale on the X-axis caused confusion for a lot of candidates in part (a). 

In parts (b) and (c) few candidates referred to ‘relative’ brain mass thereby providing incorrect responses.

In parts (b) and (c) few candidates referred to ‘relative’ brain mass thereby providing incorrect responses.

In Part (d) many candidates were familiar with the process of neuron formation in primates though some may have been confused by the introduction to the question.

Identify the parts of the ear labelled X and Y.

X:

Y: 

Describe the use of cochlear implants in deaf patients.

X: semicircular canals ✔

Y: eardrum/tympanic membrane ✔

a. sound picked up by microphone relayed electronically to speech processor ✔

b. speech processor filters background noise/selects only speech frequencies ✔

c. «radio» signal from transmitter to receiver/stimulator which converts it to electric signal ✔

d. «electrical impulses» sent to electrode «array» in cochlea
OR
cochlear implant bypasses the hair cells in the cochlea ✔

e. electrode/electrical signal stimulates auditory nerve «fibers in cochlea» ✔

f. signals «generated by implant» sent to brain «which recognizes signals as sound» ✔

OWTTE

Most candidates could identify the labelled parts of the ear.

Although many had a reasonable idea about how cochlear implants function, they were unable to describe this in sufficient detail. Many students talked about amplifying sound, not changing the sound into electric signals.

Explain the autonomic control of the pupil of the eye and how the pupil reflex is used to determine brain damage.

a. iris sphincter muscle / circular muscle / pupil constriction is controlled by the parasympathetic system ✔

b. iris dilator / radial muscle / pupil dilation is controlled by the sympathetic system ✔

c. at low light intensity pupil dilates
 OR
 at high intensity it constricts
 OR 
a reflex that controls the diameter of the pupil in response to intensity of light entering the eye ✔

d. «under normal conditions» pupils of both eyes respond identically to a light stimulus «regardless of which eye is being stimulated» ✔

e. response in one pupil without the other pupil responding is sign of a problem ✔

f. delayed response may indicate damage to brain / optic nerve / problems in oculomotor nerve/brain stem / use of depressant drugs / brain death ✔

Accept no response

Most candidates scored two marks for explaining the autonomic control of the pupil of the eye and how the pupil reflex is used to determine brain damage. The main error was mixing up the two autonomic systems. The answers were often scattered and confused.

The graph shows the relationship between body mass and brain volume in three groups of primates.

Analyse the relationship between body mass and brain volume in these primates.

a. in all groups an increase in body mass means an increase in brain volume 

b. in the apes, brain volume has increased only slightly with body mass 

c. in the Homo group brain volume increases steeply with body mass 

d. in Australopithecines brain volume has increased only slightly with body mass
OR
in Australopithecines fewer species were studied 

e. at a small mass the brain volumes are more similar

Describe how the use of cinnamon changes mouse performance on the Barnes maze.

Scientists demonstrated that cinnamon increased neural plasticity in some parts of mouse brains. Explain how neural plasticity could have affected learning in poor performer mice.

It has been suggested that cinnamon might be of benefit to patients who are recovering from a stroke. Suggest one advantage of adding cinnamon to the diet of a patient who has suffered a stroke.

a. poor performers performed «much» better after a diet with cinnamon ✔

b. cinnamon made good performers perform slightly better/the same ✔

a. developing neurons form multiple synapses, so there are more connections between neurons ✔

b. synapses that are not used do not persist/neural pruning ✔

c. less synapses means there is less interference of stimuli / less background noise ✔

d. neurons/synapses that are used a lot are reinforced so information is accessed faster in neurons ✔

a. reorganization of brain function through plasticity «which is enhanced by cinnamon» ✔

b. cinnamon helps to form new neural pathways to replace the ones that were lost «due to the stroke» ✔

Describing how the use of cinnamon changes mouse performance on the maze was successfully answered.

In part (b) most candidates got 2 marks out of 3, as they failed to fully relate the concept of neural plasticity to learning.

In (c) most candidates suggested cinnamon helps to form new neural pathways to replace the ones lost due to a stroke.

The image shows a normal human brain in vertical section.

Identify the parts of the brain labelled X and Y.

Outline the function of the nucleus accumbens.

Compare and contrast the sensory and motor functions of the left and right cerebral hemispheres of the brain.

X = cerebellum 

Y = pituitary gland

perception of pleasure / control of depression / reward centre / secretes dopamine

Compare:

a. both parts control higher order functions / example of higher order function 

b. each side controls muscle contraction on other side of body / example 

c. each side receives sensory input from sense organs from other side of body / example 

Contrast:

d. right CH controls muscles on left side but left CH controls right side 

e. right CH receives sensory input from left side of body but left CH receives from right side 

f. Broca’s / Wernicke’s / speech processing in left CH only 

g. left CH receives sensory input from RHS of visual field in both eyes but vice versa for right CH

At least one compare and one contrast needed for 3 marks.

Evaluate the claim that IGF influences turning angle and neuron extension.

Outline the development of neurons from when they are first formed in the neural tube.

a. turning angle of control is zero degrees whereas with IGF it is much larger 

b. neuron extension is greater with IGF than control 

c. non-overlapping error bars suggest a (significant) effect on turning angle
OR
overlapping error bars suggest a non-significant effect on neuron extension

a. an axon grows from each immature neuron (in response to chemical stimuli) 

b. each developing neuron forms several synapses (with other neurons) 

c. synapses that are not used degenerate 

d. neural pruning / loss of unused neurons 

e. neural connections can change / increase with experience 

f. neurons may migrate and complete development at their destination

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

Identify the part labelled X.

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

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

neurulation ✔

neural plate
OR
neural groove
OR
ectoderm ✔

spina bifida ✔

Accept a description of spina bifida

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 ✔

Identify the structures found at I, II and III.

I:

II:

III:

Suggest one way in which multiple sclerosis has affected the cerebral hemispheres of the brain.

The folding of the cerebral hemispheres is extensive and varies between different mammals. Explain briefly the importance of folding of the cerebral hemispheres in humans.

a. I: skull bone/cranium ✔

b. II: «left cerebral» hemisphere
OR
III: «right cerebral» hemisphere ✔

less white matter
OR
bigger space in the middle/ventricles
OR
overall area/volume of cortex/cerebrum is reduced/space between cortex/cerebrum and cranium bigger/number of folds is reduced
OR
slower nerve transmission
OR
fewer synapses
OR
function of cerebral hemispheres diminished ✔

a. the cerebral hemispheres are responsible for higher order functions ✔

b. the folding permits an increased surface area without increasing the cranium size
OR
permits high surface area to volume ratio ✔

c. increased surface/volume permits more synapses ✔

d. humans have a highly developed/highly folded cerebral cortex ✔

e. folding decreases distances therefore faster communication ✔

On the diagram, draw an arrow showing the direction of the light.

Identify the cells labelled A and B.

A:

B:

Explain, using the diagram, how the visual stimuli from the right eye reach the visual cortex of the brain.

[Source: reprinted by permission from Springer Nature: Nature Reviews Neuroscience
Parallel processing in the mammalian retina, Heinz Wässle, 2004,
Nat Rev Neurosci 5, 747–757 (2004) doi:10.1038/nrn1497]

Accept any arrow pointing upwards

A: bipolar cell
B: ganglion cell ✔

Both required

a. right eye receives information/stimuli/light from both «left and right» visual field ✔

b. light from the left visual field goes to the right side of the retina
OR
vice versa ✔

c. impulses «from retina» carried along the optic nerve ✔

d. «optic» nerves cross at «optic» chiasma ✔

e. impulses from the left side of the retina goes to the left side of the brain
OR
vice versa ✔

Accept any of these points made on an annotated diagram.

Outline the function of the autonomic nervous system in the human body.

Evaluate the use of the pupil reflex to test for brain damage.

a. controls involuntary processes in the body 

b. «uses centres located» in the brain stem/medulla 

c. example of action of autonomic nervous system eg: the regulation of heart rate

a. a light is shone in the eye 

b. «when light shone in eyes» if pupil does not constrict then there is some brain damage 

c. if the pupil constricts it rules out certain types of brain damage 

d. different response from each eye could indicate brain damage 

e. more testing is needed to determine area/extent of brain damage OWTTE

Discuss the methods used to identify the role of specific parts of the brain.

a. animal experiments give information about the brain under controlled laboratory conditions 

b. may not be applicable to humans / must meet high ethical standards OWTTE 

c. autopsy of a damaged brain may allow conclusions about the role of the affected part 

d. lesions/removal of part of the brain allows conclusion about functions of that part 

e. fMRI (scan) identifies brain activity as a result of stimulation (using a magnetic field) 

f. because active parts of the brain receive increased blood flow 

g. most direct method / least invasive

Describe how the inner ear detects audible sounds.

a. vibrations transmitted by the oval window «to the inner ear» ✔

b. sound waves cause vibrations/waves in cochlear fluid ✔

c. sensory hairs ‹attached to the basement membrane› are moved by the waves in the fluid ✔

d. each frequency stimulates a specific groups of hair cells ✔

e. higher frequencies detected closer to the base of the cochlea
OR
vice versa ✔

f. impulses transmitted by the auditory nerve to the brain ✔