Lesson 3.6.4.1.1

3.6.4.1.1 Homeostasis and negative feedback Quiz: AQA Biology, Unit 6

20 questions

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Lesson 3.6.4.1.1, Homeostasis and negative feedback: 20 multiple choice questions for the AQA Biology (7402), Unit 6: Organisms respond to changes in their internal and external environments, written with Revision Ninja.

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The 20 questions

  1. What is homeostasis?

    • The process by which cells divide to repair tissues
    • The movement of an organism towards a stimulus
    • The breakdown of glucose to pyruvate
    • The maintenance of a stable internal environment within restricted limits

  2. What does negative feedback do?

    • It restores a system to its original level
    • It speeds up the rate of a reaction without limit
    • It stops all physiological control
    • It increases a change until a process ends

  3. Which three components make up a homeostatic control loop?

    • Sarcomere, Z-line and A band
    • Receptor, coordinator and effector
    • Synapse, axon and myelin
    • Stomach, liver and kidney

  4. Why is a stable core temperature important in mammals?

    • Stable temperature makes blood cells larger
    • Enzyme activity depends on temperature, so stable temperature keeps metabolism working
    • Stable temperature increases the number of neurones
    • Stable temperature prevents all mutations

  5. Why is a stable blood pH important?

    • Blood pH controls the size of the heart
    • Blood pH sets the speed of conduction in nerves
    • Blood pH controls the number of red blood cells
    • Enzyme activity depends on pH, and extreme changes can denature enzymes

  6. Why must blood glucose concentration be kept stable?

    • It provides a constant supply of respiratory substrate and controls the water potential of the blood
    • It sets the number of synapses in the brain
    • It determines the colour of the blood
    • It determines the speed of conduction in neurones

  7. Which description of positive feedback is correct?

    • It restores a system to its original level
    • It is only found in plants
    • It stops all change in a system
    • It amplifies a change, moving the system further from its original level

  8. After a meal, blood glucose rises. Which mechanism restores blood glucose to normal?

    • Thyroxine is released, causing the cells to stop respiring
    • Adrenaline is released, causing blood glucose to rise further
    • Glucagon is released, causing glucose to be released from the liver
    • Insulin is released, causing cells to take up glucose and convert it to glycogen

  9. Which mechanism responds to a fall in blood glucose by releasing glucose from the liver?

    • Oxytocin released from the pituitary
    • Insulin released from the pancreas
    • Glucagon released from the pancreas
    • Adrenaline released from the adrenal medulla only

  10. What is the main effect of sweating when core temperature rises?

    • Sweat warms the blood and increases temperature
    • Sweat increases the rate of photosynthesis
    • Evaporation of sweat cools the skin and reduces core temperature
    • Sweat stops the blood flowing to the skin

  11. Shivering helps raise core temperature when the body is cold. Which type of tissue carries out shivering?

    • Smooth muscle in the gut
    • Nervous tissue in the brain only
    • Cardiac muscle only
    • Skeletal muscle

  12. Oxytocin during childbirth increases contractions, which in turn increase oxytocin release. What type of feedback is this?

    • Neither, because hormones do not affect feedback
    • Negative feedback
    • Positive feedback
    • Homeostatic feedback that stops labour

  13. Which feature of a homeostatic system helps it maintain control over a change in a variable?

    • A single mechanism that only increases the variable
    • The absence of any feedback loops
    • Separate mechanisms that control departures in opposite directions
    • Independence from receptors and effectors

  14. A person's core temperature rises to 39 degrees Celsius. Which set of responses would reduce it?

    • Sweating and vasodilation of skin blood vessels
    • Reduced breathing and slower heart rate only
    • Shivering and vasoconstriction of skin blood vessels
    • Increased heat production by skeletal muscle

  15. In a thermostat analogy of homeostasis, which part corresponds to the coordinator?

    • The control centre that processes information from receptors and sends instructions
    • The room that contains the air
    • The heater or cooler that changes the temperature
    • The sensor that detects temperature

  16. Why is positive feedback relatively uncommon in homeostasis?

    • It stops all hormones from being released
    • It drives a change further, so it is used only where a rapid, complete response is needed
    • It makes cells divide more slowly
    • It is the only mechanism that maintains a stable internal environment

  17. What would happen to enzymes if blood pH fell far below its normal range?

    • Enzymes could be denatured, reducing the rate of metabolic reactions
    • Enzymes would be unaffected because pH only affects the blood
    • Enzymes would be made more quickly
    • Enzymes would become more active at all pH values

  18. A high concentration of glucose in the blood lowers its water potential. What is the likely effect on cells?

    • Water moves into cells by osmosis, making them burst
    • Glucose moves into the cells without any change in water movement
    • Water moves out of cells by osmosis, which may affect cell function
    • The cells are unaffected because water potential does not change

  19. What is a set point in homeostasis?

    • The normal value around which a controlled variable is maintained
    • The number of receptors in a tissue
    • The maximum value a variable can ever reach
    • The time taken for a feedback loop to act

  20. Which is a good example of a negative feedback response in the body?

    • Blood clotting that amplifies platelet activation
    • Ripening of fruit that speeds up further ripening
    • Vasoconstriction of skin blood vessels in the cold, to conserve heat
    • Contractions in childbirth that increase further contractions

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