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Question 1
A man accidentally touches a hot stove and quickly moves his hand away from it. This is a reflex action. |
a) | Describe how the structures shown in the image help to coordinate a reflex action.
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b) | Which two of the following are other examples of reflex actions? A jumping in the air to catch a basketball B raising a hand to protect the eyes in bright light C releasing saliva when you smell food D running away from a dangerous animal E moving your hand away from a sharp object
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c) | How can you tell that a reflex action is not a conscious action? Use information from the diagram.
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d) | Write down one advantage of a reflex arc not involving the brain.
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e) | Explain why reflex actions are helpful adaptations that increase chances of survival.
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Question 2
Reflex actions are rapid and automatic. Babies are born with reflexes. |
a) | A baby's reflexes include: Choose two of the reflexes from the table and suggest how they help the baby to survive.
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Name the different structures in a reflex action. |
b) | The structure that detects the stimulus.
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c) | The neurone that carries the electrical impulse to the CNS.
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d) | Neurones in the CNS that allow the other neurones to communicate with each other.
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e) | The neurone that carries the electrical impulse away from the CNS.
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f) | The structure that brings about the response.
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Question 3
Neurones are specialised cells that transmit information to other neurones, muscles, or glands. |
a) | Neurones develop from undifferentiated cells. State the name of these cells.
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b) | Most neurones are longer than other types of animal cell. Suggest why most neurones are very long.
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c) | Describe the role of sensory neurones.
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d) | Most neurones in the brain are unmyelinated whereas motor neurones are myelinated. Explain why myelination is needed on motor neurones but not on neurones in the brain.
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e) | Motor neurones connect to effector organs. Give one example of an effector organ.
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Question 4
Synapses are essential to the transmission of electrical impulses from one neurone to another. The image below shows how an electrical impulse passing along a relay neurone causes an impulse to be transmitted to, and then transmitted along, a second neurone. |
a) | What type of neurone is this second neurone?
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b) | Label the diagram with the following:
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c) | The nerve impulse travels from the presynaptic neurone to the postsynaptic neurone. Draw arrows on the diagram to indicate the direction of nerve impulse travel.
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d) | Outline the process by which the nerve impulse is transmitted across the synapse.
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Question 5
Patients with Alzheimer’s disease have memory problems, thinking and reasoning difficulties, and struggle to judge distance. In an Alzheimer’s disease patient's brain, the time taken for a neurotransmitter to diffuse across the 32 nanometre synaptic gap between neurones is 6.4 × 10–7 seconds. |
a) | Calculate the speed of neurotransmitter diffusion in a person with Alzheimer’s disease. Use the formula: speed =timedistance Give your answer in metres per second.
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b) | In the brain of a healthy person, diffusion happens at a speed of 0.2 m/s. Suggest how the result obtained in e) accounts for the symptoms of Alzheimer's disease.
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c) | Patients with Alzheimer's disease also have low levels of a neurotransmitter called acetylcholine. Certain medicines that increase the levels of acetylcholine can be used as a treatment for Alzheimer's disease. Explain the effect of low levels of neurotransmitter in the communication between neurones.
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Question 6
Coffee contains caffeine. Caffeine is as a central nervous system stimulant. Two students planned an investigation to study the effect of caffeine on a person's reaction time. The students followed the steps below:
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The table below shows the students' results. |
a) | Calculate the mean distance that the ruler fell after Student A drank a cup of coffee.
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b) | Give two variables the two students controlled in their investigation.
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c) | The students used the distance that the ruler fell as a measure of the reaction time. What do the results show about the effect of caffeine on reaction time?
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d) | Suggest two ways the students could improve their investigation.
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Question 7
Morphine is a very strong painkiller. Morphine stops the release of several different neurotransmitters. This means that neurotransmitters cannot cross the synapse and bind to the receptors on the next neurone. |
a) | Use your knowledge of synapses and nerve impulse transmission to explain how morphine and other painkillers act to reduce the pain felt by the person.
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Question 8
Animals rely on sense organs to find food. |
a) | Name three receptor types a rabbit might use to help detect food in its environment. For each receptor type suggest where that receptor is likely to be found on the rabbit's body.
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b) | A branch falls off a tree near a rabbit. The rabbit jumps at the noise. Describe the processes by which the rabbit responds to the stimulus of the fallen branch.
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Question 9
A doctor tests a child’s nervous system by tapping the tendon just below the knee. |
a) | What is the name given to cells that are sensitive to stimuli?
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The child stretches his leg involuntarily. |
b) | What is the effector in this response?
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c) | This response is one example of a reflex action. The nerve pathway followed by a reflex action is called a reflex arc. Reflex arcs start with a stimulus and end up with a response from an effector. |
A girl picks up a hot plate. A reflex action causes her to drop it. Describe this example of a reflex action in terms of: stimulus ➔ receptor ➔ coordinator ➔ effector ➔ response
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d) | Some people have a condition in which information from the skin does not reach their brain. Explain why this is dangerous.
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Question 10
A man fell and hit his head. The doctors are worried that he might have suffered injuries to his spinal cord. Different areas of the man's skin were touched with a sharp object, and the man was asked if he could feel the object touching him. |
a) | Explain how the information from the man's skin reaches the man’s brain.
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b) | The man could feel the sharp object touching his arms but not his legs. Suggest what this information could tell the doctors about the damage to the man’s spinal cord. Explain your answer.
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