AQA GCSE Biology

Homeostasis & response

AQA GCSE Biology revision on Homeostasis & response. Aligned to the AQA GCSE Biology 8461 specification. This bank has 25 practice questions on this topic.

Sample questions (3 of 25)

  1. Question 1

    Homeostasis is the maintenance of...

    • A) A constant heart rate only
    • B) A constant internal environment (temperature, water, glucose) within narrow limits
    • C) External temperature
    • D) Constant blood type
    Show answer

    Answer: A constant internal environment (temperature, water, glucose) within narrow limits

    Examples: body temperature ~37C, blood glucose ~5 mmol/L, blood pH ~7.35-7.45, water balance. Each is controlled by receptors detecting change -> coordination centre (brain, spinal cord, pancreas) -> effectors (muscles, glands) -> response. Negative feedback: a deviation triggers a correction in the opposite direction.

  2. Question 2

    The nervous system uses ___ to carry signals; the endocrine system uses ___.

    • A) hormones; electrical impulses
    • B) electrical impulses; hormones
    • C) blood cells; nerves
    • D) DNA; glucose
    Show answer

    Answer: electrical impulses; hormones

    NERVOUS SYSTEM: electrical impulses along neurones, fast (~100 m/s), short-lived effect, very precise target. ENDOCRINE SYSTEM: chemical messengers (hormones) released into blood by glands, slower (seconds to minutes), longer-lasting, affects multiple target organs. Each suits different control tasks (reflexes vs metabolism).

  3. Question 3

    In a reflex arc, the correct order is...

    • A) Receptor -> sensory neurone -> relay neurone -> motor neurone -> effector
    • B) Effector -> motor neurone -> brain -> sensory neurone
    • C) Brain -> spinal cord -> muscle
    • D) Stimulus -> brain -> muscle
    Show answer

    Answer: Receptor -> sensory neurone -> relay neurone -> motor neurone -> effector

    Reflex = automatic, fast, protective response. Stimulus (e.g. pin) -> receptor (skin) -> sensory neurone -> RELAY neurone (in spinal cord - doesn't go to brain, that's why it's fast) -> motor neurone -> effector (muscle) -> response (move hand). Synapses connect neurones - chemicals (neurotransmitters) cross the tiny gap.

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22 more questions on Homeostasis & response — plus mistakes tracking and spaced repetition across the whole Biology spec.

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