AQA GCSE Biology - B5
What is homeostasis? - ANS -The regulation of conditions inside the body to maintain a
stable internal environment in response to changes in both internal and external
conditions
What things do automatic control systems regulate? - ANS -Body temperature, blood
glucose level and water content
What are the three main components that work together in automatic control systems? -
ANS -Receptors, coordination centres and effectors
What does negative feedback do? - ANS -When the level of something in the body is too
high or low, the body uses negative feedback to bring it back to normal
How does negative feedback work? - ANS -Receptor detects a stimulus - level is too high
or low. Coordination centre receives and processes the information, then organises a
response. Effector produces a response and restores the optimum level.
The effectors will continue to produce this response for as long as they are being
stimulated by a coordination centre. This sometimes leads to the opposite problem
occuring, in which case the negative feedback process starts again
What makes up the nervous system? - ANS -The central nervous system, sensory
neurones, motor neurones and effectors
What is the central nervous system? - ANS -The brain and the spinal chord, connected
to the body by sensory neurones and motor neurones
What are sensory neurones? - ANS -The neurones that carry information as electrical
impulses from the receptors to the CNS
What are motor neurones? - ANS -The neurones that carry electrical impulses from the
CNS to effectors
What are effectors? - ANS -Muscles and glands which respond to nervous impulses
What are synapses and what do they do? - ANS -They are the connections between two
neurones. The nerve signal is transferred by chemicals (neurotransmitters) which diffuse
across the gap and set off a new electrical signal in the next neurone
, What are reflexes? - ANS -Rapid, automatic responses to stimuli that don't involve the
conscious part of the brain
How does a reflex arc work? - ANS -Stimulus is detected by receptors, causing impulses
to be sent along a sensory neurone to a relay neurone in the CNS. Impulses reach a
synapse between sensory neurone and relay neurone, causing neurotransmitters to be
released, which diffuse across the gap and cause an impulse to be sent down the relay
neurone. The same thing happens when the impulses reach a synapse between the relay
neurone and the motor neurone. The impulses travel down the motor neurone to the
effector, which produces a response
How would you investigate reaction times? - ANS -Ruler drop test or computer test
What is the cerebral cortex? - ANS -The outer layer of the brain which is responsible for
conciousness, intelligence, memory and language
What is the medulla? - ANS -It controls unconscious activities such as breathing and is
at the point where the spinal cord meets the brain
What is the cerebellum? - ANS -At the back of the brain, it is responsible for muscle
coordination
How do scientists study the brain? - ANS -Studying patients with brain damage,
electrically stimulating the brain and MRI scans
How has research into the brain helped people? - ANS -Developed treatment of
disorders of the nervous system. For example, electrical stimulation can reduce muscle
tremors caused by Parkinson's
What are the risks of researching the brain? - ANS -Physical damage to the brain or
increased problems with brain function
What are the different parts of the eye? - ANS -Sclera - tough supporting wall of the eye;
Cornea - transparent outer layer at the front of the eye which refracts light into the eye;
Iris - muscles that control the diameter of the pupil and therefore how much light enters
the eye;
Lens - focuses light onto the retina;
Retina - contains receptor cells sensitive to light intensity and colour;
Ciliary muscles and suspensory ligaments - control shape of the lens;
Optic nerve - carries impulses from the receptors on the retina to the brain
How does the eye respond to light intensity? - ANS -In bright light, reflex is triggered
that causes the circular muscles in the iris to contract and the radial muscles to relax,
making the pupil smaller.
What is homeostasis? - ANS -The regulation of conditions inside the body to maintain a
stable internal environment in response to changes in both internal and external
conditions
What things do automatic control systems regulate? - ANS -Body temperature, blood
glucose level and water content
What are the three main components that work together in automatic control systems? -
ANS -Receptors, coordination centres and effectors
What does negative feedback do? - ANS -When the level of something in the body is too
high or low, the body uses negative feedback to bring it back to normal
How does negative feedback work? - ANS -Receptor detects a stimulus - level is too high
or low. Coordination centre receives and processes the information, then organises a
response. Effector produces a response and restores the optimum level.
The effectors will continue to produce this response for as long as they are being
stimulated by a coordination centre. This sometimes leads to the opposite problem
occuring, in which case the negative feedback process starts again
What makes up the nervous system? - ANS -The central nervous system, sensory
neurones, motor neurones and effectors
What is the central nervous system? - ANS -The brain and the spinal chord, connected
to the body by sensory neurones and motor neurones
What are sensory neurones? - ANS -The neurones that carry information as electrical
impulses from the receptors to the CNS
What are motor neurones? - ANS -The neurones that carry electrical impulses from the
CNS to effectors
What are effectors? - ANS -Muscles and glands which respond to nervous impulses
What are synapses and what do they do? - ANS -They are the connections between two
neurones. The nerve signal is transferred by chemicals (neurotransmitters) which diffuse
across the gap and set off a new electrical signal in the next neurone
, What are reflexes? - ANS -Rapid, automatic responses to stimuli that don't involve the
conscious part of the brain
How does a reflex arc work? - ANS -Stimulus is detected by receptors, causing impulses
to be sent along a sensory neurone to a relay neurone in the CNS. Impulses reach a
synapse between sensory neurone and relay neurone, causing neurotransmitters to be
released, which diffuse across the gap and cause an impulse to be sent down the relay
neurone. The same thing happens when the impulses reach a synapse between the relay
neurone and the motor neurone. The impulses travel down the motor neurone to the
effector, which produces a response
How would you investigate reaction times? - ANS -Ruler drop test or computer test
What is the cerebral cortex? - ANS -The outer layer of the brain which is responsible for
conciousness, intelligence, memory and language
What is the medulla? - ANS -It controls unconscious activities such as breathing and is
at the point where the spinal cord meets the brain
What is the cerebellum? - ANS -At the back of the brain, it is responsible for muscle
coordination
How do scientists study the brain? - ANS -Studying patients with brain damage,
electrically stimulating the brain and MRI scans
How has research into the brain helped people? - ANS -Developed treatment of
disorders of the nervous system. For example, electrical stimulation can reduce muscle
tremors caused by Parkinson's
What are the risks of researching the brain? - ANS -Physical damage to the brain or
increased problems with brain function
What are the different parts of the eye? - ANS -Sclera - tough supporting wall of the eye;
Cornea - transparent outer layer at the front of the eye which refracts light into the eye;
Iris - muscles that control the diameter of the pupil and therefore how much light enters
the eye;
Lens - focuses light onto the retina;
Retina - contains receptor cells sensitive to light intensity and colour;
Ciliary muscles and suspensory ligaments - control shape of the lens;
Optic nerve - carries impulses from the receptors on the retina to the brain
How does the eye respond to light intensity? - ANS -In bright light, reflex is triggered
that causes the circular muscles in the iris to contract and the radial muscles to relax,
making the pupil smaller.
