Hormones and Negative Feedback · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Slow messages, steady levels

Science · The Human Body · ages 14-15
Name ______________________   Date ____________

  1. A hormone reaches every organ, yet only some respond. Why?

    • Only they have blood vessels
    • Only they carry the matching receptor
    • Only they sit near the gland

  2. How does a hormone reach its target organ?

    • It travels in the blood
    • It runs down a nerve wire
    • It drifts through the air

  3. Nervous control is faster and shorter lived than hormonal control.

    Circle one:   True   False

  4. Blood thyroid hormones rise high. What does feedback do next?

    • It tells the pituitary to push harder
    • It tells the thyroid to ignore everything
    • It tells the pituitary to ease off

  5. Which gland releases the signal that drives the thyroid?

    • The pancreas
    • The pituitary
    • The adrenal

  6. Which parts make up a negative feedback loop?

    • Gland, nerve, muscle only
    • Blood, bone, skin
    • Sensor, control centre, effector

  7. Positive feedback holds a level steady the way negative feedback does.

    Circle one:   True   False

  8. A cut stops the thyroid signal reaching the brain. What happens to thyroid hormones?

    • They settle exactly at normal
    • They keep building past normal
    • They vanish at once
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Slow messages, steady levels W1-mt_OBa6BHmW29-s1

  1. Only they carry the matching receptor · A hormone only affects cells carrying its matching receptor.
  2. It travels in the blood · Hormones are chemical messengers carried everywhere by the blood.
  3. True · Nerves trade speed for brevity, while hormones trade slowness for duration.
  4. It tells the pituitary to ease off · Rising levels signal the brain to stop pushing, easing the pituitary off.
  5. The pituitary · The pituitary signals the thyroid to release its hormones.
  6. Sensor, control centre, effector · A sensor watches, a centre compares, and an effector pushes back.
  7. False · Positive feedback amplifies a change to finish a job, as in childbirth. Steady levels need negative feedback.
  8. They keep building past normal · With no stop signal the gland keeps releasing past the set point.
Worksheet · LightMySky