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Exam questions · Biology · Homeostasis

Temperature Control and the Skin

  • 7 exam questions
  • 20 marks
  • 8 quick checks
  1. 1 State [1 mark]

    State the part of the brain that acts as the coordination centre for temperature control.

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    Model answer

    The hypothalamus.

    Mark scheme

    • Hypothalamus — 1 mark
  2. 2 Name [3 marks]

    Figure 1 shows a section through the skin. Name the parts shown at A, B and C.

    A section through the skin with three parts marked A, B and C.
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    Model answer

    A is a sweat gland. B is a hair erector muscle. C is the fat layer.

    Mark scheme

    • A: sweat gland — 1 mark
    • B: hair erector muscle — 1 mark
    • C: fat layer — 1 mark
  3. 3 Explain [3 marks]

    Explain how sweating helps to cool the body.

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    Model answer

    The sweat glands release sweat onto the surface of the skin. The sweat evaporates. Evaporation takes heat energy from the skin and the body, so the body cools.

    Mark scheme

    • Sweat is released onto the skin — 1 mark
    • It evaporates — 1 mark
    • Evaporation takes heat from the body — 1 mark
  4. 4 Explain [4 marks]

    Explain how vasodilation helps to lower body temperature on a hot day.

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    Model answer

    The hypothalamus detects the high temperature. The blood vessels near the surface of the skin widen. More blood flows near the surface, so more heat is transferred from the blood to the surroundings. The body temperature falls.

    Mark scheme

    • Hypothalamus detects the rise — 1 mark
    • Blood vessels near the surface widen — 1 mark
    • More blood flows near the surface — 1 mark
    • More heat is lost to the surroundings — 1 mark
  5. 5 Describe [4 marks]

    Describe how the body responds when the temperature of the surroundings falls.

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    Model answer

    Receptors in the skin and the hypothalamus detect the fall. The muscles shiver, which releases heat from respiration. The blood vessels near the surface of the skin narrow, so less heat is lost. The hairs stand up and trap a layer of air, and sweating stops.

    Mark scheme

    • Receptors detect the fall in temperature — 1 mark
    • Shivering releases heat — 1 mark
    • Blood vessels narrow — 1 mark
    • Hairs stand up / sweating stops — 1 mark
  6. 6 Explain [3 marks]

    Explain why temperature control is an example of negative feedback.

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    Model answer

    If the body temperature changes, receptors detect the change and the effectors respond. The response reverses the change, for example cooling the body when it is too hot. The temperature returns to normal.

    Mark scheme

    • Change detected by receptors — 1 mark
    • The effectors respond — 1 mark
    • The response reverses the change — 1 mark
  7. 7 Explain [2 marks]

    A student says that hairs standing up is not an effective way for humans to keep warm. Explain why the student is correct.

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    Model answer

    Hairs standing up trap a layer of air that insulates the skin. Humans have very little body hair, so only a very thin layer of air is trapped.

    Mark scheme

    • Trapped air insulates — 1 mark
    • Humans have little body hair — 1 mark

Quick check

  1. 1

    Which part of the brain monitors the temperature of the blood?

    1. AThe cerebrum
    2. BThe cerebellum
    3. CThe hypothalamus
    4. DThe medulla
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    C: The hypothalamus

    The hypothalamus monitors blood temperature.

  2. 2

    What happens to the blood vessels near the skin surface when you are too hot?

    1. AThey widen
    2. BThey narrow
    3. CThey disappear
    4. DThey close
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    A: They widen

    They widen, which is vasodilation.

  3. 3

    What does shivering do?

    1. ACools the body
    2. BMakes sweat
    3. CWidens blood vessels
    4. DReleases heat from respiration
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    D: Releases heat from respiration

    Shivering makes muscles contract and release heat from respiration.

  4. 4

    Why does sweating cool the body?

    1. ASweat is cold
    2. BEvaporation takes heat from the skin
    3. CSweat blocks the pores
    4. DSweat makes blood vessels narrow
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    B: Evaporation takes heat from the skin

    Evaporation of sweat takes heat from the skin.

  5. 5

    What is vasoconstriction?

    1. AThe widening of blood vessels
    2. BThe release of sweat
    3. CThe narrowing of blood vessels
    4. DThe standing up of hairs
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    C: The narrowing of blood vessels

    Vasoconstriction is the narrowing of blood vessels near the skin surface.

  6. 6

    What do the hairs do when it is cold?

    1. ALie flat
    2. BFall out
    3. CGrow longer
    4. DStand up
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    D: Stand up

    The hair erector muscles contract, so the hairs stand up and trap air.

  7. 7

    Why does skin look pale when it is cold?

    1. ALess blood flows near the surface
    2. BMore blood flows near the surface
    3. CThe blood is cold
    4. DThe sweat glands are working
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    A: Less blood flows near the surface

    Less blood flows near the surface, because the vessels narrow.

  8. 8

    At about what temperature does the body control its core temperature?

    1. A30 °C
    2. B37 °C
    3. C40 °C
    4. D25 °C
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    B: 37 °C

    The body controls its core temperature at about 37 °C.