Co-ordination & Response (Edexcel GCSE Biology)
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What are the brain structures labelled A-C on the diagram?
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What are the brain structures labelled A-C on the diagram?
The structures are:
A = cerebrum / cerebral cortex / cerebral hemispheres
B = medulla oblongata
C = cerebellum
What is the role of the cerebral hemispheres in the brain?
The cerebral hemispheres are responsible for higher brain functions such as consciousness, intelligence, memory and language.
True or False?
The cerebellum in the brain is involved with the control of heart rate.
False.
The cerebellum in the brain is responsible for the coordination of movement.
Which body functions are regulated by the medulla in the brain?
The medulla in the brain regulates unconscious functions such as:
breathing
heart rate
digestion
Why is it difficult to study the brain? (Higher Tier Only)
It is difficult to study the brain because it is inside the skull and is therefore difficult to access.
How can brain function be investigated? (Higher Tier Only)
Brain function can be investigated using scanning technology, e.g.
CT scanning
PET scanning
What information can different types of brain scan provide? (Higher Tier Only)
Information that can be provided by different types of brain scan includes:
CT scan = brain structure
PET scan = brain activity, and therefore the functions of different regions of the brain
True or False?
Spinal cord damage is difficult to treat because it is inaccessible. (Higher Tier Only)
False.
Spinal cord injuries are difficult to treat because:
tissues of the nervous system do not repair themselves in the way that other tissues do
adult stem cells cannot currently be encouraged to differentiate into new spinal cord neurones to replace damaged cells
It is the brain itself that is difficult to access, due to its location inside the skull.
Why are brain tumours difficult to treat? (Higher Tier Only)
Brain tumours are difficult to treat because:
brain tissue is difficult to access
treatment risks damaging unaffected brain tissue
the blood-brain barrier may prevent drugs from reaching affected cells
What is the role of a sensory receptor in the nervous system?
Receptors are specialised cells that detect specific stimuli and convert them into electrical impulses, initiating the transmission of signals through the nervous system.
What is the neurone type shown in the image?
The neurone shown in the image is a sensory neurone. It can be identified by the position of the cell body between a dendron and an axon.
What is the function of a sensory neurone?
Sensory neurones carry impulses from sense organs to the central nervous system (CNS).
Which two organs make up the central nervous system (CNS)?
The CNS is made up of the brain and the spinal cord.
What is the neurone type shown in the image?
The neurone shown in the image is a relay neurone. Relay neurones can be identified because they are short and have a small cell body at one end with many dendrites.
What is the neurone type shown in the image?
The neurone is a motor neurone, identifiable by its long axon with a large cell body at one end.
True or False?
Motor neurones carry impulses from effectors to the central nervous system (CNS).
False.
Motor neurones carry impulses from the CNS to effectors (muscles or glands).
True or False?
The nerve impulse travels toward the cell body in all neurone cells.
False.
A nerve impulse travels towards the cell body in sensory neurones and away from the cell body in motor and relay neurones.
What are the structures labelled A and B in the diagram?
Structures A and B are:
A = myelin sheath
B = axon
True or False?
The myelin sheath insulates axons and prevents nerve impulses from travelling too fast.
False.
The myelin sheath insulates axons in order to increase the speed at which nerve impulses are transmitted.
What is the difference between a dendron and an axon?
Dendrons carry impulses towards the cell body (in sensory neurones), while axons carry impulses away from the cell body.
Define the term synapse.
A synapse is a junction between two neurones where a very small gap exists between one neurone and the next.
Define the term neurotransmitter.
Neurotransmitters are chemical signalling molecules used to transfer signals between neurones at synapses.
True or False?
Electrical impulses can jump across the gap at a synapse.
False.
Electrical impulses cannot directly jump the gap at synapses. Electrical signals are converted into chemical signals in the form of neurotransmitters which diffuse across a synapse gap.
Describe the events that tale place at a synapse.
The events at a synapse are as follows:
neurotransmitters are released from vesicles
neurotransmitters diffuse across the gap between neurones
neurotransmitters bind to receptor molecules on the second neurone
a new electrical impulse is generated in the second neurone
True or False?
Neurotransmitters move across synapses by active transport.
False.
Neurotransmitters move across the gap at a synapse by diffusion from a high concentration to a low concentration.
What are reflex actions?
Reflex actions are automatic, rapid responses to a stimulus that do not involve conscious thought.
Write a flow diagram to represent a reflex arc.
A flow diagram that represents a reflex arc would be as follows:
receptor → sensory neurone → relay neurone → motor neurone → effector
True or False?
Sensory neurones in a reflex arc connect receptor cells with the conscious brain.
False.
Sensory neurones in a reflex arc connect receptor cells with relay neurones in the CNS.
While there are some reflex arcs that involve the brain, the brain regions involved are not connected with conscious thought.
What is a relay neurone?
A relay neurone is a neurone within the CNS that connects sensory and motor neurones.
What is the role of a motor neurone in a reflex arc?
Motor neurones in reflex arcs connect relay neurones with effectors.
What are the structures labelled A-D on the diagram below?
The structures labelled A-D are:
A = iris
B = cornea
C = lens
D = retina
What is the function of the cornea?
The function of the cornea is to refract light into the eye.
True or False?
The function of the iris is to focus light onto the back of the eye.
False.
The function of the iris is to control the amount of light that enters the pupil.
It is the cornea and lens that focus light correctly onto the retina.
What is the function of cone cells?
Cone cells absorb light of different colours/wavelengths, providing colour vision.
True or False?
Rod cells function effectively at low light levels.
True.
Rod cells work well in dim light.
What defects can affect the eye and eyesight?
Defects that affect the eye and eyesight include:
cataracts
long-sightedness
short-sightedness
colour blindness
True or False?
In individuals with short-sightedness, the light that enters the eye is focused in front of the retina instead of onto the retina.
True.
Short sighted individuals are unable to focus on distant objects because the light focuses in front of the retina.
What does it mean for an individual to be long sighted?
Long sighted individuals cannot focus on near objects.
What can cause long-sightedness?
Long-sightedness occurs when light from near objects focuses behind the retina; this can be due to:
a shortened eyeball
a lens / cornea that is not curved enough and does not refract light to the extent needed
What are cataracts?
Cataracts are a build-up of protein inside the lens, producing a cloudy effect at the front of the eye.
True or False?
Colour blindness occurs when rod cells in the retina do not detect light.
False.
Colour blindness results from incorrectly functioning or absent cone cells.
True or False?
Long-sightedness can be corrected with the use of a diverging (concave) lens.
False.
Long-sightedness can be corrected with the use of a converging (convex) lens, which causes the light to bend more and so focus on the retina instead of behind the retina.
Diverging (concave) lenses are used to correct short-sightedness.
How can cataracts be corrected?
Cataracts can be corrected by removing the cloudy lens and replacing it with an artificial lens.