Neurobiology and Behaviour: WJEC A Level Biology Notes

Lesson 1 of 25

What are the main parts of the human brain?

These notes cover Option C, Neurobiology and behaviour, in WJEC A level Biology Unit 4: , Inheritance and Options. Each lesson follows the WJEC specification, and the exam tips come from BioWelsh analysis of WJEC past papers.

The brain is the swollen front end of the , with the spinal cord. An adult brain has a mass of about 1.4 kg and contains roughly 86 billion , each connected to thousands of others. It is protected by the skull and by three membranes called the , and it floats in , which cushions it and supplies nutrients. The brain develops from three swellings, so it is described as three regions. The hindbrain ( and ) controls basic, automatic functions. The midbrain relays information for vision and hearing. The forebrain contains the , , and , and carries out the most complex processing.

The diagram below shows the brain cut down the middle from front to back (a sagittal section). You must be able to find each labelled structure.

Illustration of the left half of a human brain cut down the midline, front on the left. The large pink folded cerebrum fills the top. A tan arch below it is labelled corpus callosum, and a small oval in the centre is labelled thalamus. Below and in front, labels point to the hypothalamus and to the pituitary gland, a small bulb hanging on a stalk. At the back, below the cerebrum, a finely folded structure is labelled cerebellum. A pale column running down is labelled medulla oblongata where it narrows and spinal cord below. A note says the hippocampus is not cut in this section because it lies deeper, on the inner side of each temporal lobe. — Section through the middle of the human brain. Labels added by BioWelsh. Photo: Patrick J. Lynch, CC BY 2.5. Resized.

The is the largest part. Its folded outer layer is the , and its two halves () are joined by the , a thick band of fibres.
The sits in the middle of the brain, below the . It relays sensory impulses to the .
The lies just below the , and the hangs from it on a short stalk.
The is at the back, below the , with a finely folded surface.
The is the lowest part of the brain stem and joins the spinal cord.

The is not cut in a section through the middle. There is one in each , curved along the inner side of the , level with the ears. It is part of the , a ring of structures around the involved in emotion, learning and memory.

Lesson 2 of 25

What do the cerebrum, hypothalamus, cerebellum and medulla oblongata do?

Main functions of the parts of the brain
Part	Main functions
	Conscious thought, voluntary actions, learning, memory, reasoning, language, personality and interpreting sensory information
	: body temperature, water balance (blood solute concentration), hunger, thirst and sleep; controls the and the
	Coordinates voluntary movement so it is smooth and precise; balance and posture; learning motor skills such as writing or playing an instrument
	Automatic of breathing (ventilation centre), heart rate and blood pressure (cardiovascular centre), and such as swallowing, coughing and vomiting
	Learning and spatial memory (finding your way); consolidating short-term memories into long-term memory; helps release

The diagram below shows where the and the rest of the lie inside the brain.

Line drawing of a head seen from the side with the brain cut down the middle. Coloured curved bands surround the centre: a blue cingulate gyrus at the top, an orange corpus callosum, and pink and lilac curves ending in a thicker pink structure low down labelled hippocampus. Other labels name the hypothalamic nuclei, the amygdala and the thalamus. — The limbic system and hippocampus inside the brain. Photo: OpenStax College, CC BY 3.0. Resized.

The is labelled at the lower end of the curved limbic structures, deep in the .
The is at the centre, and the hypothalamic sit just below and in front of it.
The arches over the top of these structures.

Lesson 3 of 25

What do the sympathetic and parasympathetic nervous systems do?

The nervous system has two parts: the (brain and spinal cord) and the (all other ). The peripheral system includes the nervous system, which controls skeletal muscles voluntarily, and the . The controls internal organs such as the heart, gut, bladder and glands without conscious thought. It is controlled by the and the . It has two divisions that are : they have opposite effects on the same organ, which gives very precise , like pressing an accelerator and a brake.

The two divisions of the autonomic nervous system
Feature	Sympathetic	Parasympathetic
at the target organ
General effect	Excitatory: prepares for activity ()	Inhibitory: conserves energy (rest and digest)
Heart rate and ventilation rate	Increase	Decrease
Pupils	Dilate	Constrict
Digestion	Slowed	Stimulated
Where the relay () are	Close to the spinal cord	Close to or in the target organ

The diagram below shows how the two divisions change heart rate through the (), the heart's pacemaker.

Flow diagram. A purple box at the top reads cardiovascular centre in the medulla oblongata. Arrows lead to two columns. The left column reads: exercise, more carbon dioxide, so blood pH falls; cardioacceleratory centre stimulated; impulses along sympathetic neurones; noradrenaline released on to the SAN; SAN fires more often, heart rate rises. It is labelled sympathetic, excitatory. The right column reads: rest or sleep, blood pH back to normal; cardioinhibitory centre stimulated; impulses along the vagus (parasympathetic) nerve; acetylcholine released on to the SAN; SAN fires less often, heart rate falls. It is labelled parasympathetic, inhibitory. — How the autonomic nervous system changes heart rate. Original BioWelsh diagram.

During exercise more carbon dioxide is produced, blood pH falls, and chemoreceptors send impulses to the cardiovascular centre in the .
Its cardioacceleratory centre sends impulses along , which release at the , so the fires more often and heart rate rises.
At rest the cardioinhibitory centre sends impulses along the vagus (), which releases , so the fires less often and heart rate falls.

In a threat, the activates the system: heart rate and ventilation rate rise, bronchioles dilate, blood is diverted to skeletal muscles and glucose is released, so muscles get more oxygen and glucose for . The adrenal glands also release adrenaline into the blood, which reinforces these effects.

Lesson 4 of 25

How does the hypothalamus link the nervous and endocrine systems?

The nervous system sends fast electrical impulses, while the endocrine system sends slower chemical messages, hormones, in the blood. The joins the two. It receives impulses from the rest of the brain and responds by controlling the just below it.

How the hypothalamus controls the two lobes of the pituitary gland
Lobe	How the hypothalamus controls it	Example
	in the make hormones, which travel down their and are stored in the , then released into the blood when impulses arrive	for water balance; in birth
Anterior	The releases releasing hormones into a small portal blood vessel, which carries them to the anterior , where they trigger release of its own hormones	triggers , which makes the adrenal glands release

The diagram below shows this link at work in the of , the stress hormone, through the , and adrenal (HPA) axis.

Vertical flow of six boxes joined by arrows: stress; hippocampus; hypothalamus; anterior pituitary gland; adrenal glands (cortex); cortisol in the blood. Arrow labels read nerve impulses, nerve impulses, CRH and vasopressin (ADH), and ACTH in the blood. A red dashed arrow runs from cortisol in the blood back up to the hippocampus, labelled cortisol binds to glucocorticoid receptors. A second red dashed arrow runs from the hippocampus to the hypothalamus, labelled inhibitory impulses, with a minus sign. A note explains negative feedback: rising cortisol makes the hippocampus inhibit the hypothalamus, so less CRH and ACTH are released and cortisol falls again. — Control of cortisol release by the hypothalamus, pituitary and adrenal axis. Original BioWelsh diagram.

Stress causes the to send impulses to the .
The releases () and vasopressin ().
These stimulate the anterior to release () into the blood.
makes the adrenal glands release , which raises blood glucose and helps the body cope with stress.
binds to in the , which then inhibits the . This is , so returns to normal.

Lesson 5 of 25

How is the cerebral cortex organised into lobes?

The is the outer layer of the , only 2 to 4 mm thick. It is , made of the of . Their run deeper inside, forming . This is the opposite way round from the spinal cord, where is in the middle. The is deeply folded. Folding increases its surface area, so far more fit inside the skull, allowing more connections and more complex processing. Mammals, and especially primates, have a larger and more folded than fish or reptiles. The has two joined by the . Each controls, and receives information from, the opposite side of the body, because most fibres cross over as they pass through the brain stem and spinal cord.

Each is divided into four lobes, named after the skull bones above them. The diagram below shows them.

Side view of a brain, front on the left. The front section is coloured red and labelled frontal lobe, the top middle section purple and labelled parietal lobe, the back section green and labelled occipital lobe, and the lower side section blue and labelled temporal lobe. Other labels point to the central sulcus between the frontal and parietal lobes, the precentral and postcentral gyri on either side of it, the lateral sulcus above the temporal lobe and the parieto-occipital sulcus. The cerebellum and brain stem are uncoloured below. — The four lobes of a cerebral hemisphere. Photo: OpenStax, CC BY 4.0. Resized.

The is at the front, in front of the (a deep groove running down the side).
The lies behind the at the top.
The is at the side, below the lateral sulcus, level with the ears.
The is at the back. The lies underneath it.

The four lobes and their main roles
Lobe	Main roles
Frontal	Reasoning, planning, problem solving, emotions and personality; contains the ; (speech) in the
Parietal	Contains the (touch, temperature, pain, body position); spatial awareness; taste
Temporal	Hearing (); (understanding language) in the ; memory, with the on its inner side; recognising faces and objects
Occipital	Vision: contains the

Lesson 6 of 25

What do the sensory, motor and association areas of the cortex do?

receive impulses from , relayed through the . The sensory (somatosensory) , just behind the , receives touch, pressure, temperature and pain from the opposite side of the body. The () and () receive impulses from the eyes and ears.
send impulses to , the skeletal muscles. The is the strip just in front of the . Each part controls muscles on the opposite side of the body.
make up most of the . They interpret sensory information by comparing it with stored memories, give it meaning, and plan responses that are passed to the . For example, the visual recognises that a shape is a face.

The diagram below shows the main functional areas of the left .

Schematic side view of a left cerebral hemisphere with the front on the left, the cerebellum below the back and the brain stem below. A vertical line marks the central sulcus, with a red strip in front labelled motor cortex and a blue strip behind labelled sensory cortex. A sloping line marks the lateral sulcus. An orange patch in the lower frontal lobe is labelled Broca's area, motor area for speech. A yellow strip below the lateral sulcus is labelled auditory cortex. A green patch further back in the temporal lobe is labelled Wernicke's area, understanding language. A green dashed curve joining the orange and green patches is labelled arcuate fasciculus. A purple area at the back is labelled visual cortex. The uncoloured front of the frontal lobe is labelled association area, planning and reasoning. — Functional areas of the left cerebral hemisphere. Original BioWelsh diagram.

The (red) is in front of the in the ; the (blue) is directly behind it in the .
The (purple) is at the back of the .
The (yellow) is on the upper edge of the , below the lateral sulcus.
(orange) is in the , and (green) is in the , joined by the .

A is an interruption of the blood supply to part of the brain, so there die from lack of oxygen and glucose. About 85% of strokes are ischaemic, caused by a blood clot blocking an artery; the rest are haemorrhagic, caused by bleeding. The effects depend on the area damaged. A in the left paralyses the right side of the body, and if is also damaged the person cannot speak fluently.

Lesson 7 of 25

What do the sensory and motor homunculi show?

Along the and the , each body part is controlled from its own region, in order from the toes (at the top, near the midline) to the face and tongue (lower down the side). The regions are not in proportion to the size of the body parts. A ('little man') is a drawing or model of the body with each part drawn in proportion to the area of that serves it. The figures below map the body on to a slice through the .

Drawing of a slice through the sensory cortex, with body parts written along its folded edge from hip, leg, foot and toes at the top to eye, nose, face, lips, teeth, tongue and pharynx at the bottom. Beside the slice, a distorted figure is drawn with each part in proportion to its area of cortex: a very large hand and fingers draped over the top, and very large lips and tongue, while the trunk and legs are small. — The sensory homunculus mapped on to the sensory cortex. Photo: OpenStax College, CC BY 3.0. Resized.

Diagram of a curved slice of cerebral cortex with its outer edge divided into coloured segments, each labelled with the body part it controls. Going round from the midline: toes, ankles, knees, hips, trunk, shoulders, elbows, wrists, hands, fingers, thumbs, neck, eyebrows and eyelids, eyeballs, face, lips, jaw, tongue, salivation, chewing and swallowing. The segments for the hands, fingers, face, lips and tongue are much wider than those for the legs and trunk. — Map of the body on the motor cortex of the right hemisphere. Photo: CNX OpenStax, CC BY 4.0. Resized.

The first figure maps the body on to the : the hand, lips, tongue and face take up a very large share.
The trunk, legs and back take up only a small share even though they are large parts of the body.
The second figure maps the of the right : the segments for the fingers, thumb, face, lips, jaw and tongue take up far more of the strip than those for the hips, knees and trunk.

Sensory : the area of for each part is proportional to the of sensory there, so fingertips, lips and tongue have large areas and are very sensitive.
Motor : the area of for each part is proportional to the complexity and precision of its movements, so the hands and face (speech, expressions) have large areas.
The two are similar but not identical: the genitals, for example, have a larger sensory area than .

Lesson 8 of 25

Which areas of the cerebrum control language and speech?

In most people language is controlled mainly by one , usually the left. This is called . It was discovered by studying the brains of patients with language problems after death, and later confirmed by stimulating or anaesthetising one of patients who were awake. and are joined by a bundle of fibres, the ; if it is damaged, a person understands and speaks fluently but cannot repeat words they hear.

The two language areas
Feature	Broca's area	Wernicke's area
Where	of the left , near the part of the for the face	of the left , behind the
Kind of area		Association (sensory) area
Role	Plans speech and sends impulses to the muscles of the mouth, tongue, larynx and breathing	Understands spoken and written language
Effect of damage	Broca's : the person understands speech but speaks slowly, with effort and missing words	Wernicke's : fluent speech with little meaning ('word salad') and poor understanding

Repeating a word you hear

1) Ears
2)
3) (understands the word)
4)
5) (plans the speech)
6)
7) Muscles of the mouth and larynx

Sign language uses the same areas. When a deaf person signs, is active as in speech, the is more active because signing uses the hands, face and body, and the is active to read signs. The receives no sound, but in people deaf from birth it is taken over for processing signs, an example of .

Lesson 9 of 25

How can the brain be studied without surgery: EEG, CT and MRI?

Early knowledge of the brain came from studying people with brain injuries and from surgery. Today scanning lets scientists and doctors study the living brain without opening the skull. Some methods show structure (what is there) and others show activity (what is working). () uses electrodes placed on the scalp to record the tiny voltage changes produced by the electrical activity of millions of in the . The trace shows waves of different frequencies.

is used to diagnose epilepsy (sudden spikes during a seizure) and sleep disorders, to confirm brain death and to monitor the depth of anaesthesia. It records changes over milliseconds, is cheap, silent and safe with a pacemaker, but it only detects activity near the surface and cannot show structure.

() takes many X-ray images from different angles as the X-ray tube rotates around the head. A computer combines them into cross-sectional slices. shows structure: tumours, skull , bleeding and whether a is caused by a clot or a bleed. A scan takes only seconds, but X-rays are , which slightly increases the risk of cancer.

The traces and photographs below show and in use.

Four wavy traces stacked one above another over a scale bar of 1 second. Beta, 14 to 30 hertz, awake and alert: small, fast waves. Alpha, 8 to 13 hertz, awake, relaxed, eyes closed: larger, slower waves. Theta, 4 to 7 hertz, drowsy or light sleep: slower still. Delta, below 4 hertz, deep sleep: about two large, slow waves in the second. — EEG traces of four kinds of brain wave. Original BioWelsh diagram.

Close-up of the top of a person's head in a white mesh cap. Many round grey electrodes in white holders sit on the cap, each connected to a thin grey wire, and the wires run together towards the back. — An EEG cap with electrodes on the scalp. Photo: Chris Hope, CC BY 2.0. Resized.

A large white ring-shaped machine in a hospital room, with a padded table covered in a white sheet leading into the hole in the ring. — A CT scanner. Photo: liz west, CC BY 2.0. Resized.

Black and white cross-section of a head seen from above. A bright white ring of skull surrounds grey brain tissue. In the middle, two dark butterfly-shaped spaces are the fluid-filled ventricles. A thin pale line runs from front to back between the two hemispheres. — A CT scan slice through a healthy adult brain. Photo: Department of Radiology, Uppsala University Hospital, CC0.

Beta waves are fast (14 to 30 Hz) and small, seen when a person is alert; alpha waves (8 to 13 Hz) appear when relaxed with the eyes closed; theta waves are slower still.
Delta waves are slow (below 4 Hz) and large, seen in deep sleep.
The electrode cap has many grey disc electrodes touching the scalp.
In the scanner the patient lies on the table, which slides into the ring; the X-ray tube and detectors rotate inside the ring.
In the slice, bone of the skull is white, brain tissue is grey and the fluid-filled ventricles in the middle are dark.

() uses a very strong magnetic field to line up hydrogen () in water molecules. A pulse of radio waves knocks them out of line, and as they realign they give out radio signals. Different tissues give different signals, so a computer builds detailed images of soft tissue, showing , , tumours and conditions such as multiple sclerosis. uses no , but it is expensive, slow and noisy, can make people claustrophobic, and cannot be used on people with metal in their bodies such as a pacemaker or cochlear implant.

Lesson 10 of 25

How do fMRI and PET show which parts of the brain are active?

() shows activity rather than structure. Active use more oxygen, so blood flow to them increases. Oxyhaemoglobin and deoxyhaemoglobin respond differently in the magnetic field, so the scanner detects where oxygenated blood is arriving (the BOLD signal, blood oxygen level dependent). Scans taken every second or two show which areas become active during a task, such as speaking, reading or moving a hand.

() uses a radioactive tracer. The most common is (), glucose containing radioactive fluorine. Active cells take up more glucose, so they take up more , which becomes trapped inside them. The fluorine gives out positrons, which meet electrons and produce gamma rays that the scanner detects. detects cancer spreading, diagnoses Alzheimer's disease early, and with other tracers shows for such as . It exposes the patient to , is expensive, and the tracer decays quickly so it must be made nearby.

The images below show an result and two scans.

Grey MRI of a head from the left side, showing the folded brain inside the skull, with the face on the left. A small orange patch in the lower part of the frontal lobe is marked by a yellow arrow labelled left IFG. — An fMRI result shown on an MRI of the left side of a head. Photo: Shima Ovaysikia, Khalid A. Tahir, Jason L. Chan and Joseph F. X. DeSouza, CC BY 2.5. Resized.

Two coloured brain scans seen from above on black backgrounds. The left, labelled PET scan of normal brain, is mostly red and yellow with green and blue patches. The right, labelled PET scan of Alzheimer's disease brain, is mostly dark purple and blue, with only a few small yellow and red spots in the middle. — PET scans of a healthy brain and a brain with Alzheimer's disease. Photo: US National Institute on Aging, Public domain.

The image is an of the left side of a head. The orange patch in the lower , labelled left IFG (inferior frontal gyrus, which contains ), became active while the person paid attention to words.
In a scan, red and yellow show high glucose use (high activity), and green, blue and purple show low activity.
The scan of a brain with Alzheimer's disease has much less red and yellow than the healthy brain, because glucose use is in affected areas.

Comparing the methods of studying the brain
What it detects	Shows	Main drawback
Voltage changes from	Electrical activity, millisecond by millisecond	Only surface activity; no structure
X-rays absorbed by tissues	Structure
Radio signals from hydrogen in a magnetic field	Detailed structure of soft tissue	Not with metal implants; noisy and enclosed
Changes in blood oxygen	Activity during a task	Expensive; activity shown indirectly
Gamma rays from a radioactive tracer	Activity (glucose use) and	; expensive

Lesson 11 of 25

How does the brain develop, and what are critical periods?

A baby is born with almost all of its , but most connections between them form after birth. In the first years of life form very rapidly. that are used repeatedly are strengthened; those that are not used are removed. This removal of unused is called , and it continues through childhood into adolescence.

The graph below shows how the number of per changes with age.

Line graph with age from 0 to 20 years on the horizontal axis and mean number of synapses per neurone in thousands from 0 to 16 on the vertical axis. The line rises steeply from 2.5 at birth to a peak of 15 at about 2 to 3 years, labelled peak at 2 to 3 years. It then falls gradually, labelled synaptic pruning, to about 10 at 12 years and 7.3 at 20 years. — Mean number of synapses per neurone in the cerebral cortex with age. Original BioWelsh graph.

At birth each has about 2500 .
By 2 to 3 years this has risen to about 15 000, the peak.
then reduces the number through childhood and adolescence to about 7000 to 8000 in adults. The remaining pathways are strong and efficient, described as hard wired.

A is a window of time when the brain is especially sensitive to a particular kind of , which it needs to develop a skill normally. If the right is missing, the for that skill are and the skill is very hard or impossible to learn later. For example, if one eye of a young kitten is covered during its , it never sees properly with that eye, even though the eye itself is normal.

Language: the for learning language, especially grammar, is roughly the first five years. New words can be learned throughout life.
Babies can tell apart the speech sounds () of every language, but by about one year they lose this for sounds they have not heard. This is why many native Japanese speakers find the English sounds l and r hard to tell apart.
Deaf babies babble less and their language is delayed unless they are given another language, such as sign language, early.
Repeated ear infections in the first years can delay language by reducing what the child hears.
Children raised with almost no human contact (feral or severely neglected children), such as a girl found at the age of 13, never developed full language despite years of teaching.
Adults across cultures speak to babies in child-directed speech: short sentences, high pitch and stretched vowels, which helps babies pick out words.

Lesson 12 of 25

What is neuroplasticity, and how does the brain recover from injury?

is the ability of the brain to change its neural pathways, so it can respond to changes in the environment and compensate for injury or disease. It was once thought the adult brain could not change, but brain imaging shows that it changes throughout life.

: a becomes stronger or weaker, for example by releasing more or having more on the postsynaptic membrane. Pathways used often become stronger, which underlies learning and memory. (If are unfamiliar, read the Nervous system lesson on synaptic transmission.)
Structural plasticity: grow new and branches and form new , and unused are .
Non-: the excitability of the itself changes, for example by altering the channels in its or .

The diagram below shows how lets the brain rebuild a pathway after a .

Three panels joined by arrows. Before: three pink neurones in a row are joined by arrows from neurone 1 to neurone 2, and two separate blue neurones lie below. Just after the stroke: a grey circle labelled damaged area covers the middle pink neurone, which is pale, and the pathway is dashed. Weeks of rehabilitation: green arrows run from neurone 1 down to the first blue neurone, across to the second blue neurone and up to neurone 2, around the damaged area. A note says nearby undamaged neurones grow new dendrites and axon branches and form new synapses, making a new route that repeated use strengthens. — Neuroplasticity after a stroke. Original BioWelsh diagram.

Before the , impulses pass along a pathway from 1 to 2.
The kills in one area, so that pathway is broken and a function such as movement of an arm is lost.
During rehabilitation, undamaged nearby grow new and branches and form new , creating a new route around the damage.
Repeating the exercises many times strengthens the new , so the function slowly returns.

People who lose one sense often use that area for another: in people blind from birth the is active when reading Braille, and in deaf people the helps process sign language.
London taxi drivers, who learn thousands of streets, have a larger back (posterior) part of the than people who do not.
Age matters: the young brain is much more plastic because it has more and is still forming pathways. A child who has a soon after birth may develop language in the right instead of the left. In an adult, has the number of , so recovery is slower and needs many repetitions.
Squirrels that learn to get nuts from a new feeder show changes in the volume of parts of the over the following weeks.

Lesson 13 of 25

How does gene expression affect brain development and behaviour?

At least a third of human are expressed mainly in the brain, more than in any other organ. As the brain develops, are switched on and off at particular times and in particular places, and this controls which form, where they migrate and which connections they make. A fault in one of these can change behaviour.

A in the FOXP2 in one family caused serious difficulty controlling the mouth and face muscles for speech, and problems with grammar.
In fragile X syndrome, a repeated DNA sequence in one becomes , so the is switched off. The protein it codes for is needed at , and its absence causes learning difficulties.

changes alter expression without changing the base sequence. of DNA usually switches off, and of proteins usually switches them on. (If is unfamiliar, read the Inheritance lesson on epigenetics.) The environment, such as diet, stress, drugs and the care a baby receives, can change these marks, so the environment can have long-lasting effects on the brain.

Rat pups that are licked and groomed a lot by their mothers have less of the in the , so they make more . Their on works well and they grow into calm adults. Neglected pups become anxious adults with high .
Female pups from attentive mothers become attentive mothers themselves, so the effect passes to the next generation through behaviour.
Children whose mothers went hungry during pregnancy in the Dutch famine of 1944 had different of some and a higher risk of obesity and heart disease as adults.

Lesson 14 of 25

How can altered gene expression in childhood increase the risk of mental illness?

Conditions such as depression, anxiety and schizophrenia run in families, and twin studies show that play a part. But no single causes them. They are , and the many interact with each other and with the environment. A person can inherit a susceptibility and never become ill.

Adults who suffered abuse, neglect or other trauma as children have a much higher risk of depression, anxiety, post-traumatic stress disorder and substance abuse. One explanation is that stress during the of brain development causes changes. For example, more of the in the fewer , so cannot switch off its own release by . Supporting evidence comes from Cushing's disease, in which a of the releases too much . is then high all the time, and many patients develop depression or anxiety.

The graph below compares blood in two adults before and after a short stressful event.

Line graph with time after the start of the stressful event from 0 to 120 minutes on the horizontal axis and blood cortisol concentration in nanograms per cubic centimetre from 0 to 25 on the vertical axis. A blue line for an adult with a secure childhood starts at 5, peaks at about 17 at 30 minutes and falls back to 5 by 120 minutes. A red line for an adult who suffered childhood trauma starts at 11, rises to about 22 at 45 to 60 minutes and is still 19 at 120 minutes. — Blood cortisol before and after a short stressful event. Original BioWelsh graph.

In the adult with a secure childhood, rises to a peak at about 30 minutes, then falls back to the resting level as works.
In the adult who suffered childhood trauma, the resting level is already about twice as high, the peak is higher, and stays high for the whole two hours.
Constantly high is to a higher background stress level and greater vulnerability to mental illness.

Lesson 15 of 25

What is innate behaviour, and why do woodlice show kineses and taxes?

Behaviour is everything an animal does in response to its surroundings or to other animals. is inborn and instinctive: it does not have to be learned, and it is performed in the same way by all members of a . It is especially important in animals with simple nervous systems and short lives, which have little time or ability to learn.

: rapid, automatic responses to a that protect the animal, such as an earthworm pulling back into its burrow when touched. (If are unfamiliar, read the Nervous system lesson on the reflex arc.)
: the whole animal changes its speed or its rate of turning according to the intensity of a , not its direction. In the speed changes; in the rate of turning changes.
: the whole animal moves directly towards (positive) or away from (negative) the direction of a . The bacterium Escherichia coli swims towards glucose (positive ), and woodlice move away from light (negative ).

Woodlice are small land crustaceans. The photograph and diagram below show a woodlouse and how woodlice use a and a .

Close-up of a woodlouse in a damp crevice of soil and bark. Its oval body is covered by overlapping grey-brown plates with pale edges, it has two long jointed antennae at the front and several thin legs underneath. — A common woodlouse, *Oniscus asellus*. Photo: Katja Schulz, CC BY 4.0. Resized.

Two panels. Left panel, orthokinesis in dry and humid air: a rectangle split into a pale dry half and a blue humid half. In the dry half a long red zigzag path crosses most of the area, labelled dry, fast and far. In the humid half several woodlice sit with only short blue paths, labelled humid, slow, little movement. Text says the rate of movement depends on the intensity of the stimulus, not its direction. Right panel, negative phototaxis: a yellow light on the left, and five blue arrows run straight away from it to five woodlice on the right. Text says each woodlouse moves directly away from the light. — Kinesis and taxis in woodlice. Original BioWelsh diagram.

The woodlouse has overlapping grey plates, seven pairs of legs and long antennae. Unlike insects it has no waterproof waxy layer, so it loses water quickly in dry air.
In dry air a woodlouse moves quickly and further, so it soon leaves the dry area.
In humid air it slows down and moves little, so woodlice collect in damp places. They are not attracted to each other; they just stop moving there.
Near light, each woodlouse moves directly away from it, so woodlice end up in dark places such as under stones and logs.

Lesson 16 of 25

How do you investigate woodlice behaviour with a choice chamber?

The specification says you should safely and ethically use organisms to measure animal responses with a for woodlice. This is working scientifically, so it is not a specified practical, but its method, variables and statistics can be examined. The diagram below shows a from the side and from above.

Two views. Side view: a round container with a clear domed lid; woodlice walk on a gauze platform; below the gauze, one half holds water, labelled humid side, and the other holds white granules of a drying agent such as anhydrous calcium chloride, labelled dry side. Top view: a circle divided into four quarters: dry and light at the top left, humid and light at the top right, dry and dark at the bottom left and humid and dark at the bottom right, where most of the woodlice are. Labels explain that black paper under the lid makes the lower half dark and that woodlice are placed through a hole in the centre and counted in each area at fixed times. — A choice chamber for investigating woodlice behaviour. Original BioWelsh diagram.

The base is divided into sections. Water under one side makes the air there humid; a drying agent such as anhydrous calcium chloride or silica gel under the other side makes it dry.
A gauze platform stops the woodlice touching the chemicals, and a clear lid keeps the air conditions steady.
Covering half the lid with black paper adds a light and dark choice, giving four areas.

Set up the chamber and leave it for about 10 minutes so the humidity in each side becomes steady.
Place 10 woodlice of the same on the gauze in the centre, through the hole in the lid.
Count the woodlice in each area every minute for 10 minutes.
Repeat with fresh woodlice, swapping which side is dry, to cancel out any other difference between the sides.
Keep light, temperature and the number, and size of woodlice the same when testing humidity.
Act ethically: handle woodlice gently with a soft paintbrush or a pooter, keep them in the chamber for as short a time as possible, never let them touch the drying agent, and return them to where they were found.

Results are tested with the . (If this test is unfamiliar, read the Inheritance lesson on the chi-squared test.) The is that there is no difference in the numbers of woodlice in the two sides, so the expected number in each is half the total.

Lesson 17 of 25

What are habituation and imprinting?

is a relatively permanent change in behaviour as a result of past experience. Learning lets an animal adjust to its own surroundings, which cannot do. The specification names , and classical and .

is learning to ignore a repeated that is followed by neither a reward nor a punishment. It is the simplest kind of learning. It saves energy and time, because the animal stops making useless escape responses and can get on with feeding. Birds learn to ignore a scarecrow, and people stop noticing the noise of a road. Foetuses at 30 to 34 weeks stop startling after a harmless vibration is repeated several times, which shows the brain can already learn before birth.

The graph below shows in snails that were tapped gently on the shell once a minute.

Line graph with the number of the tap from 1 to 15 on the horizontal axis and snails that withdrew, as a percentage from 0 to 100, on the vertical axis. The line falls steadily from 100% at the first tap to about 60% at the fifth, 26% at the tenth and 13% at the fifteenth. — Percentage of snails that withdrew into their shells after each tap. Original BioWelsh graph.

At the first tap every snail withdrew into its shell.
The percentage withdrawing fell with each tap, to about 13% by the fifteenth.
The snails learned that the tap was harmless, so they stopped wasting energy and feeding time on hiding.

is rapid learning that happens only during a short soon after hatching or birth. Young birds that leave the nest early, such as geese and ducks, follow the first large moving object they see and hear, which is normally their mother. Konrad Lorenz showed that greylag goslings that saw him first followed him everywhere. keeps the young close to a parent for warmth, food and protection, and later helps them recognise a mate of their own .

Lesson 18 of 25

How do classical conditioning, operant conditioning and latent learning work?

Conditioning is learning to associate two things. In the animal links two ; in it links its own behaviour with a consequence. The diagram below shows Ivan Pavlov's experiment on in dogs.

Three columns joined by arrows. Before conditioning: a box reading food, unconditioned stimulus, with an arrow to salivation, unconditioned response; below, a box reading bell, neutral stimulus, with an arrow to no salivation. During conditioning, repeated: a box reading bell plus food, rung just before feeding, with an arrow to salivation, unconditioned response. After conditioning: a box reading bell alone, conditioned stimulus, with an arrow to salivation, conditioned response. — Classical conditioning. Original BioWelsh diagram.

Food is an unconditioned : it causes salivation, an unconditioned response, without any learning.
A bell is at first a neutral and causes no salivation.
The bell is rung just before feeding many times.
Now the bell alone causes salivation. The bell has become a conditioned , and salivation to it is a conditioned response.

is learning by trial and error to link a particular behaviour with a reward or a punishment. B. F. Skinner put rats in a box with a . When a rat pressed the by chance, food appeared, and it soon learned to press the often. The food is a positive reinforcer. Switching off an unpleasant , such as a loud noise, when the is pressed also increases the behaviour (negative reinforcement). A punishment, such as a mild electric shock, decreases the behaviour.

The diagram below shows a Skinner box.

Schematic side view of a box containing a rat. On the left wall a food dispenser is joined by a dashed line to a food tray low down, and a lever sticks out between them; the rat's front paw reaches up to the lever. A round light is on the upper wall and a loudspeaker in the top right corner. The floor is a metal grid. Labels explain that pressing the lever releases food as a reward or stops a noise as negative reinforcement, that the light can signal when pressing works, and that the grid floor could give a mild shock as punishment. — A Skinner box for studying operant conditioning. Original BioWelsh diagram.

The releases food into the tray or switches off the noise from the loudspeaker.
A light can signal when pressing the will work.
A metal grid floor could deliver a mild shock as a punishment.

happens without any reward, when an animal explores its surroundings. The information is stored and used later, for example to escape a predator. Edward Tolman compared rats in a maze that were given food at the end every day, only from day 11, or never.

The graph below shows results like Tolman's.

Line graph with day from 1 to 17 on the horizontal axis and mean number of errors from 0 to 30 on the vertical axis. Group 1, food every day, falls steadily from 24 to 5. Group 3, never given food, falls slowly from 25 to 17. Group 2, food from day 11 only, follows group 3 down to 18 on day 11, then drops sharply to 5.5 on day 13 and ends at 4, below group 1. — Mean number of errors made by three groups of rats in a maze. Original BioWelsh graph.

Group 1, fed every day, made fewer errors day by day: .
Group 3, never fed, improved only slowly: without reward.
Group 2 made many errors until day 11. Once food was given, its errors fell at once, below those of group 1. It must have learned the layout of the maze during days 1 to 10 without reward.

Lesson 19 of 25

How do primates learn by imitation and insight?

Primates, including humans, live in large, complex societies with long periods of childhood. They have large brains, and learn a great deal by watching others and by working things out. is copying the behaviour of another individual, usually of the same . It is a form of social learning, so a useful behaviour can spread quickly through a group and be passed on to the next generation without any change in . On one Japanese island, a young female macaque began washing sweet potatoes in the sea to remove sand, and the habit spread to most of her group. Different chimpanzee use stones, sticks or branches to crack nuts, and these local traditions are sometimes called culture.

The photograph below shows a Japanese macaque.

Close-up of a monkey with thick grey-brown fur and a bare pink face, looking up towards the camera from grass. — A Japanese macaque, *Macaca fuscata*. Photo: Letartean, CC BY 3.0. Resized.

Japanese macaques live in large troops with a clear social structure.
Food washing spread through one troop by , first to young relatives of the inventor, then to others.

is solving a new problem suddenly by thinking it through, using things learned before, rather than by trial and error. Wolfgang Köhler hung bananas out of reach of chimpanzees and gave them boxes and sticks. After a pause, some chimpanzees stacked the boxes or joined two sticks together to reach the fruit. In humans, brain scans show a burst of activity in the right at the moment of .

Lesson 20 of 25

involves interactions between individuals of the same that form structured social groups, in which the behaviour of one individual influences the others. Social animals need to communicate, and the group usually has a clear organisation.

Living in a social group
Advantages	Disadvantages
Better defence: more eyes to spot predators, and each individual is less likely to be caught	Competition for food, mates and nest sites
Cooperative hunting of larger prey	Diseases and parasites spread more easily
Cooperative care of young	A large group is more easily seen by predators
Division of labour, which increases	Low-ranking animals may get little food or never breed
Young learn skills by watching others	Stress from constant contact and aggression

Much communication uses . A is a specific signal from one individual that triggers a in another. A is an , stereotyped sequence of movements that, once started, is usually completed. A gull chick pecks at the red spot on its parent's bill, which makes the parent bring up food; a greylag goose rolls an egg back into its nest and finishes the movement even if the egg is taken away.

The photograph and diagram below show the classic stickleback experiment on .

Close-up of the head of a small fish underwater. It has a large silvery-blue eye, and its throat and lower head are bright red-orange, fading to brown and speckled above. — Head of a male three-spined stickleback in breeding colours. Photo: Piet Spaans, CC BY 2.5. Resized.

On the left, a realistic grey fish shape with spines, an eye and a tail and a silver underside, labelled realistic shape, silver underside, rarely attacked. On the right, two crude grey oval shapes with an eye and a red lower half, labelled crude shapes with a red underside, attacked often. Text says the red underside, not the shape of a fish, is the sign stimulus that releases the fixed action pattern of attack. — Models shown to male sticklebacks defending a territory. Original BioWelsh diagram.

In the breeding season a male three-spined stickleback develops a red throat and belly and defends a .
A realistic model with a silver underside was rarely attacked by territorial males.
Crude shapes with a red underside were attacked often. The red colour, not the fish shape, is the that releases the of attack.

Fixed action patterns and reflexes compared
Feature	Fixed action pattern	Reflex
Complexity	A sequence of coordinated movements	A single simple response
Effect of learning	Can be modified and perfected by learning	Cannot be changed by learning
Starting it	Depends on the animal's motivation (for example hunger)	Always happens when the is given

Lesson 21 of 25

Ants, bees, wasps and termites have the most organised animal societies, called . A has three features: individuals care for young that are not their own, several generations live together, and there is division of labour into , groups that each do only certain jobs.

The photograph below shows a honeybee queen surrounded by workers.

Close-up of honeybees on pale yellow wax comb. In the centre is a bee with a long, smooth orange abdomen, much longer than those of the striped bees crowding round her. On the right, several open six-sided cells contain white larvae. — A honeybee queen surrounded by workers on the comb. Photo: Jessica Lawrence, Eurofins Agroscience Services, Bugwood.org, CC BY 3.0. Resized.

The queen is the bee in the centre with a long, smooth orange abdomen; she is the only female and lays all the eggs. White larvae can be seen in the open cells on the right.
The workers around her are sterile females. They clean her, feed her and spread her through the .

Queen: one per ; lays up to 2000 eggs a day; her (queen substance) stops workers' ovaries developing.
Drones: a few hundred males; their only role is to mate with young queens from other .
Workers: tens of thousands of sterile females. With age they move from cleaning cells and feeding larvae, to building wax comb and guarding the entrance, to foraging for and .

Why should workers give up breeding to raise the queen's offspring? The diagram below shows part of the answer.

A pink box for the queen, female, diploid, each egg gets a random half of her genes, and a blue box for the drone, male, haploid, every sperm carries all of his genes. Pink and blue arrows cross to two cream boxes, worker 1 and worker 2, both female and diploid. Text below: genes from the drone are identical in both sisters, half of each sister's genes times 100% shared is 50%; genes from the queen are shared by half on average, half times 50% is 25%; total shared between sisters is 50% plus 25%, which is 75%, compared with 50% for brothers and sisters in humans. — Why sister worker bees share on average 75% of their genes. Original BioWelsh diagram.

Queens and workers are , but drones develop from unfertilised eggs and are .
Every from a drone carries all of his , so sisters share all of their father's .
Each sister gets a random half of the queen's , so sisters share half of those.
On average sisters share 75% of their , so helping to raise sisters passes on more of a worker's than raising her own offspring (50%) would.

Communication in insect societies is : by touch, by and by dances. A forager returning from food dances on the vertical comb in the dark hive, as shown below.

Two panels. Left, on the vertical comb inside the hive: honeycomb background with a dashed arrow pointing straight up. A red zigzag waggle run points up and to the right at 40 degrees from vertical, with dashed return loops curving back to its start on the left and on the right. Right, outside, seen from above: a hive at the bottom with a dashed arrow up towards the sun, and a red arrow at 40 degrees to the right of it leading to pink flowers. Text says to fly at 40 degrees to the right of the sun, and the longer the waggle run, the further away the food. — How the waggle dance shows the direction of food. Original BioWelsh diagram.

A round dance the food is close to the hive (within about 50 to 100 m) but gives no direction.
A is used for food further away. The bee runs straight while waggling its abdomen, then loops back alternately left and right.
The angle of the waggle run from vertical equals the angle between the sun and the food, seen from the hive.
The longer the waggle run lasts, the further away the food is. Other workers also learn the scent of the flowers from the dancer.

Lesson 22 of 25

How do dominance hierarchies organise vertebrate groups?

Many vertebrate groups are organised by dominance. This needs animals that recognise each other as individuals and can learn and remember who is stronger. The diagram below shows three kinds of social group.

Three diagrams. Egalitarian, all equal rank: four identical circles in a row. Despotic, one dominant, the rest equal: a gold circle labelled D with arrows down to four identical circles. Linear hierarchy, a pecking order: five circles A to E in a vertical column joined by downward arrows, with A in gold at the top, and text saying each animal is dominant over all those below it. — Three kinds of social group in vertebrates. Original BioWelsh diagram.

Egalitarian: all members have equal rank, as in shoals of herring.
Despotic: one individual is and all the others are equally submissive, as in meerkats.
Linear : each animal is over all those below it, like the pecking order first described in hens. This is the most common kind in vertebrates.

In a , higher-ranking individuals are over lower-ranking ones, and animals are submissive to those of higher rank. Once established, the ranks are fairly stable, so animals do not need to fight each time they meet. Rank is settled mainly by . Red deer stags in the rut roar at each other and walk side by side, judging each other's size and antlers; the weaker usually backs down, and the two clash antlers only as a last resort.

The photograph below shows two red deer stags during the rut.

Two large stags with branched antlers beside a lake in parkland. One stands in shallow water on the left and the other on the grassy bank to the right, a few metres apart, watching each other. A photographer's web address is printed small in the corner. — Two red deer stags in the rut. Photo: Andy Morffew, CC BY 2.0. Resized.

Two stags stand a short distance apart beside a lake, one in the water and one on the bank, watching each other instead of fighting straight away.
Displays such as this let each stag assess the other and avoid a fight it would lose.

Less aggression over food, mates and breeding sites, because each animal knows its place.
Maintaining rank by displays rather than fights reduces the risk of injury.
individuals get the best food and more matings, so the fittest pass on their . In baboons, high-ranking males mate more often and high-ranking females raise more surviving young.
Low-ranking animals still gain the protection of the group, and may rise in rank later.
Costs: low-ranking animals get less food and may never breed, and ranks can change, as young males challenge and replace older ones. In stable hierarchies low-ranking baboons tend to have higher , a sign of stress, but in naked mole-rats the queen has high levels of stress hormones.

Lesson 23 of 25

Why do animals defend territories and court mates?

A is an area that an animal (or a group) defends against other members of its . It gives the owner a supply of food, a nest site or a place to mate, so holding a good increases reproductive success. It also spaces animals out, which reduces competition and the spread of disease.

Scent: urine, faeces or scent glands; ring-tailed lemurs rub scent glands on branches, and cats spray urine.
Sound: male European robins and many other birds sing from perches around the edge of the .
Sight: the robin's red breast is displayed to intruders; other animals use postures and coloured patches.
Owners usually defend a with , such as postures, calls and displays, rather than fighting. The intruder usually retreats, so both avoid injury.

The photographs below show a European robin and a bowerbird's bower.

A small plump bird with a bright orange-red face and breast, grey-brown back and wings and a pale belly, perched on a wooden post against a blurred green background. — A European robin, *Erithacus rubecula*. Photo: Jacob Spinks, CC BY 2.0. Resized.

Woodland floor covered in leaf litter under thin trees. In the middle is a structure of upright twigs forming a small avenue. In front of it lies a cluster of pale shells, and small coloured objects are scattered nearby. — The bower of a male bowerbird. Photo: John Robert McPherson, CC0.

The bright orange-red breast is a visual signal to other robins.
Males sing to advertise the and attack robins that enter it; fights are occasionally fatal.
The bower is an avenue of twigs built on the ground by a male bowerbird to court females.
He collects objects such as pale shells and small coloured items and places them around the bower. The female visits several bowers and watches each male's display before choosing.

is the behaviour by which animals attract and choose a mate. It lets animals recognise a mate of the same and the opposite sex, check that the partner is sexually mature and receptive, and synchronise their behaviour so that mating succeeds. Because it ensures mating within the , leads to offspring. Many displays are chains of , each one the for the next.

chain in three-spined sticklebacks

1) Female with an egg-swollen abdomen appears
2) Male performs a zigzag dance
3) Female swims towards him
4) Male leads her to the nest
5) Male points to the entrance
6) Female enters and lays eggs
7) Male fertilises the eggs

Lesson 24 of 25

How has sexual selection shaped territorial and courtship behaviour?

is for characteristics that increase an individual's success in getting mates. for the features that win more matings are passed on more often, so the features become more exaggerated over generations. often acts the other way, because bright colours, large ornaments and noisy displays attract predators and cost energy.

Two kinds of sexual selection
Feature	Intra-sexual selection	Inter-sexual selection
What happens	Members of one sex (usually males) compete with each other for mates	One sex (usually females) chooses a mate from the other
Traits favoured	Large size, strength, weapons such as antlers and tusks, aggression	Bright colours, ornaments, songs and displays
Examples	Red deer stags; southern elephant seal bulls; black grouse fighting at a	Peacocks; stickleback males with bright red throats; bowerbirds

In , winners of contests mate with many females, so the for size and aggression spread. This produces , where males and females look different: male southern elephant seals can be several times heavier than females. In a , males gather in one place to display or fight, and females choose among the winners. Female choice is explained by two models. In the physical attractiveness model, females prefer the most attractive males; a brighter red stickleback throat is favoured, and the red comes from food, so it also signals a healthy, well-fed male. In the , ornaments are costly, so only a high-quality male can survive with them, and the ornament is an honest signal of good .

The photographs below show one trait from each kind of .

A peacock facing the camera with his bright blue neck and breast, in front of a huge fan of long tail feathers covered in green, blue and bronze eyespots. — A peacock displaying his tail. Photo: Rohit Sharma, CC BY 4.0. Resized.

A stag with large branched antlers stands in shallow water at the edge of a misty field, head raised and mouth open as he roars. A photographer's web address is printed small in the corner. — A red deer stag roaring during the rut. Photo: Andy Morffew, CC BY 2.0. Resized.

A peacock displays his long, elaborate tail feathers covered in eyespots. Peahens are dull brown.
A red deer stag roars during the rut. Loud, deep roars signal a large, strong stag to rival males.

Lesson 25 of 25

Putting the topic together

How the ideas in neurobiology and behaviour connect

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Zoom in to read each branch. Swipe or scroll sideways to explore.

Neurobiology and behaviour
- The brain
  - Parts and functions; links and hormones
  - : and
  - : lobes, sensory, motor and , , language
- Neuroscience
  - , , , and
  - , and
  - , , and mental illness
- Behaviour
  - : , ,
  - Learned: , , conditioning, latent, ,
  - Social: insect , dominance, , ,

release , not adrenaline; release .
The consolidates memories into long-term storage; say more than learning and memory.
Each controls the opposite side of the body; is usually on the left.
and show activity; and show structure.
are non-directional; are directional.
Define as inborn or instinctive, not inherited.
In percentage change, divide by the original value.

What are the main parts of the human brain?

What do the cerebrum, hypothalamus, cerebellum and medulla oblongata do?

What do the sympathetic and parasympathetic nervous systems do?

How does the hypothalamus link the nervous and endocrine systems?

How is the cerebral cortex organised into lobes?

What do the sensory, motor and association areas of the cortex do?

What do the sensory and motor homunculi show?

Which areas of the cerebrum control language and speech?

How can the brain be studied without surgery: EEG, CT and MRI?

How do fMRI and PET show which parts of the brain are active?

How does the brain develop, and what are critical periods?

What is neuroplasticity, and how does the brain recover from injury?

How does gene expression affect brain development and behaviour?

How can altered gene expression in childhood increase the risk of mental illness?

What is innate behaviour, and why do woodlice show kineses and taxes?

How do you investigate woodlice behaviour with a choice chamber?

What are habituation and imprinting?

How do classical conditioning, operant conditioning and latent learning work?

How do primates learn by imitation and insight?

How do dominance hierarchies organise vertebrate groups?

Why do animals defend territories and court mates?

How has sexual selection shaped territorial and courtship behaviour?

Putting the topic together

Worksheets

Worksheet 1: Option C Neurobiology and behaviour (156 marks)

Check your understanding.

Image A shows a section through the human brain. Which row correctly identifies structures A, C and D?

Neurobiology and behaviour

What are the main parts of the human brain?

What do the cerebrum, hypothalamus, cerebellum and medulla oblongata do?

What do the sympathetic and parasympathetic nervous systems do?

How does the hypothalamus link the nervous and endocrine systems?

How is the cerebral cortex organised into lobes?BWRBioWelsh recommendedWe recommend revising this because it has appeared regularly in past papers. Asked in 3 of 7 WJEC exam series (2017 to 2025), 15 marks in total. This is a revision priority, not a prediction of your exam.

What do the sensory, motor and association areas of the cortex do?BWRBioWelsh recommendedWe recommend revising this because it has appeared regularly in past papers. Asked in 3 of 7 WJEC exam series (2017 to 2025), 15 marks in total. This is a revision priority, not a prediction of your exam.

What do the sensory and motor homunculi show?

Which areas of the cerebrum control language and speech?BWRBioWelsh recommendedWe recommend revising this because it has appeared regularly in past papers. Asked in 3 of 7 WJEC exam series (2017 to 2025), 17 marks in total. This is a revision priority, not a prediction of your exam.

How can the brain be studied without surgery: EEG, CT and MRI?BWRBioWelsh recommendedWe recommend revising this because it has appeared regularly in past papers. Asked in 4 of 7 WJEC exam series (2017 to 2025), 10 marks in total. This is a revision priority, not a prediction of your exam.

How do fMRI and PET show which parts of the brain are active?BWRBioWelsh recommendedWe recommend revising this because it has appeared regularly in past papers. Asked in 4 of 7 WJEC exam series (2017 to 2025), 10 marks in total. This is a revision priority, not a prediction of your exam.

How does the brain develop, and what are critical periods?BWRBioWelsh recommendedWe recommend revising this because it has appeared regularly in past papers. Asked in 3 of 7 WJEC exam series (2017 to 2025), 10 marks in total. This is a revision priority, not a prediction of your exam.

What is neuroplasticity, and how does the brain recover from injury?BWRBioWelsh recommendedWe recommend revising this because it has appeared regularly in past papers. Asked in 4 of 7 WJEC exam series (2017 to 2025), 17 marks in total. This is a revision priority, not a prediction of your exam.

How does gene expression affect brain development and behaviour?

How can altered gene expression in childhood increase the risk of mental illness?

What is innate behaviour, and why do woodlice show kineses and taxes?

How do you investigate woodlice behaviour with a choice chamber?

What are habituation and imprinting?BWRBioWelsh recommendedWe recommend revising this because it has appeared regularly in past papers. Asked in 3 of 7 WJEC exam series (2017 to 2025), 12 marks in total. This is a revision priority, not a prediction of your exam.

How do primates learn by imitation and insight?

What are the advantages and disadvantages of living in social groups?

How are insect societies organised, and how do bees communicate?

How do dominance hierarchies organise vertebrate groups?

Why do animals defend territories and court mates?

How has sexual selection shaped territorial and courtship behaviour?

Putting the topic together

Worksheets

Worksheet 1: Option C Neurobiology and behaviour (156 marks)

Check your understanding.

How is the cerebral cortex organised into lobes?

What do the sensory, motor and association areas of the cortex do?

Which areas of the cerebrum control language and speech?

How can the brain be studied without surgery: EEG, CT and MRI?

How do fMRI and PET show which parts of the brain are active?

How does the brain develop, and what are critical periods?

What is neuroplasticity, and how does the brain recover from injury?

What are habituation and imprinting?