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Exam questions · Biology · The Nervous System

Sensory Receptors and Neurones

  • 6 exam questions
  • 21 marks
  • 9 quick checks
  1. 1 Name [2 marks]

    Name the two types of effector in the human body.

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    Model answer

    Muscles and glands.

    Mark scheme

    • Muscle — 1 mark
    • Gland — 1 mark
  2. 2 State [2 marks]

    State what is meant by the term stimulus, and give one example.

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    Model answer

    A stimulus is a change in the environment that can be detected by a receptor. An example is a bright light, a loud sound or a hot object.

    Mark scheme

    • A change in the environment detected by a receptor — 1 mark
    • A suitable example — 1 mark
  3. 3 Complete [4 marks]

    The path taken by an impulse when a person steps on a pin is shown below, with the missing words replaced by letters. Stimulus, then A, then sensory neurone, then B, then motor neurone, then C, then response. Name the parts A, B and C.

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    Model answer

    A is a receptor (pain receptor). B is the central nervous system (the spinal cord or brain), with a relay neurone. C is an effector (a muscle).

    Mark scheme

    • A: receptor — 1 mark
    • B: central nervous system / spinal cord — 1 mark
    • C: effector — 1 mark
    • Muscle given as the example of an effector — 1 mark
  4. 4 Describe [3 marks]

    Describe the function of a motor neurone.

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    Model answer

    A motor neurone carries electrical impulses from the central nervous system, which is the brain or spinal cord, to an effector. The effector is a muscle or a gland, which then carries out the response.

    Mark scheme

    • Carries impulses / electrical signals — 1 mark
    • From the central nervous system — 1 mark
    • To an effector (muscle or gland) — 1 mark
  5. 5 Explain [4 marks]

    Explain how the structure of a motor neurone is adapted to its function.

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    Model answer

    A motor neurone has a very long axon, so it can carry impulses over a long distance, for example from the spinal cord to a muscle in the foot. The axon is covered with a myelin sheath, which insulates it and makes the impulse travel much faster. At the end it has branched axon terminals, which let it connect to the muscle fibres.

    Mark scheme

    • Long axon — 1 mark
    • Carries impulses over long distances — 1 mark
    • Myelin sheath insulates / speeds up impulses — 1 mark
    • Branched ends connect to the effector or other neurones — 1 mark
  6. 6 Compare [6 marks]

    Compare the structure and function of a sensory neurone, a relay neurone and a motor neurone.

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    Model answer

    A sensory neurone carries impulses from a receptor, such as one in the skin, to the central nervous system. It has a long dendron, and the cell body lies to one side. A relay neurone lies wholly inside the CNS and passes impulses from the sensory neurone to the motor neurone. It is short and has many branches so that it can connect to several neurones. A motor neurone carries impulses from the CNS to an effector, which is a muscle or a gland. It has a long axon with a myelin sheath, and its cell body is in the CNS.

    Mark scheme

    • Sensory neurone carries impulses from receptor to CNS — 1 mark
    • Feature of a sensory neurone, such as a long dendron — 1 mark
    • Relay neurone is inside the CNS — 1 mark
    • Relay neurone passes impulses from sensory to motor neurone — 1 mark
    • Motor neurone carries impulses from CNS to an effector — 1 mark
    • Feature of a motor neurone, such as a long axon or myelin sheath — 1 mark

Quick check

  1. 1

    What is the name for a change in the environment that can be detected?

    1. AA response
    2. BA stimulus
    3. CAn effector
    4. DA reflex
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    B: A stimulus

    A change in the environment that a receptor can detect is called a stimulus.

  2. 2

    Which two organs make up the central nervous system?

    1. ABrain and heart
    2. BSpinal cord and muscles
    3. CBrain and spinal cord
    4. DSpinal cord and skin
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    C: Brain and spinal cord

    The central nervous system is the brain and the spinal cord.

  3. 3

    Which of these is an effector?

    1. AA muscle
    2. BA sensory neurone
    3. CA receptor cell in the eye
    4. DThe spinal cord
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    A: A muscle

    Muscles and glands are effectors because they carry out the response.

  4. 4

    Which type of neurone carries impulses from the CNS to a muscle?

    1. ASensory neurone
    2. BRelay neurone
    3. CReceptor
    4. DMotor neurone
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    D: Motor neurone

    Motor neurones carry impulses away from the central nervous system to an effector.

  5. 5

    Where is a relay neurone found?

    1. AIn the skin
    2. BIn the brain or spinal cord
    3. CIn a muscle
    4. DIn the retina
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    B: In the brain or spinal cord

    Relay neurones are inside the CNS, where they connect sensory and motor neurones.

  6. 6

    What is the function of the myelin sheath?

    1. ATo detect stimuli
    2. BTo store energy for the neurone
    3. CTo insulate the neurone and speed up the impulse
    4. DTo release hormones
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    C: To insulate the neurone and speed up the impulse

    Myelin is a fatty layer that insulates the neurone and makes impulses travel faster.

  7. 7

    Which sequence shows the correct route of an impulse in a nervous response?

    1. AReceptor, sensory neurone, CNS, motor neurone, effector
    2. BReceptor, motor neurone, CNS, sensory neurone, effector
    3. CEffector, sensory neurone, CNS, motor neurone, receptor
    4. DReceptor, CNS, effector, sensory neurone, motor neurone
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    A: Receptor, sensory neurone, CNS, motor neurone, effector

    The impulse passes from a receptor along a sensory neurone to the CNS, and then along a motor neurone to an effector.

  8. 8

    Which part of a neurone carries the impulse away from the cell body?

    1. AThe dendron
    2. BThe nucleus
    3. CThe myelin sheath
    4. DThe axon
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    D: The axon

    The axon carries impulses away from the cell body. The dendron carries them towards it.

  9. 9

    In multiple sclerosis the myelin sheath is damaged. What effect does this have?

    1. AImpulses travel faster
    2. BImpulses travel more slowly or are lost
    3. CNeurones become shorter
    4. DMore neurotransmitter is released
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    B: Impulses travel more slowly or are lost

    Without the insulating myelin, impulses travel more slowly or are lost, so messages in the nervous system are delayed.