GCSE Biology Topic 5: Homeostasis and Response MCQs – 30 Practice Questions with Answers (AQA 8461)
Free practice for AQA GCSE Biology 8461 on homeostasis and response, covering control systems, the nervous system, hormones, temperature and water balance, and plant responses, with a short explanation after every question.
Homeostasis and Control Systems
Q1. What is meant by homeostasis?
- (A) The breakdown of food in the gut
- (B) The regulation of internal conditions to keep them at optimum levels
- (C) The transport of oxygen around the body
- (D) The production of new cells by division in growing tissues and during repair
Show Answer
Answer: B – Homeostasis is the regulation of the internal conditions of a cell or organism so that optimum conditions for function are maintained.
Q2. Which three conditions are controlled by homeostasis in the human body?
- (A) Blood glucose concentration, body temperature and water levels
- (B) Heart rate, breathing rate and blood pressure, which change constantly during exercise and rest
- (C) Height, body mass and appetite
- (D) Blood group, eye colour and hair colour
Show Answer
Answer: A – In the human body, homeostasis includes control of blood glucose concentration, body temperature and water levels.
Q3. Why is homeostasis important for cells?
- (A) It stops cells dividing so that tissues never need to grow or be repaired
- (B) It makes cells larger
- (C) It prevents all disease
- (D) It maintains optimum conditions for enzyme action and cell functions
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Answer: D – Cells can only survive within narrow physical and chemical limits, so homeostasis keeps conditions optimum for enzymes and cell functions.
Q4. What is the role of a receptor in a control system?
- (A) It carries out the response by contracting or secreting, like an effector does
- (B) It stores hormones
- (C) It detects a stimulus, a change in the environment
- (D) It produces energy for the response
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Answer: C – Receptors are cells that detect stimuli, which are changes in the environment.
Q5. What does a coordination centre do in a control system?
- (A) It receives and processes information from receptors
- (B) It detects light intensity in the eye and sends impulses to the brain
- (C) It contracts to produce movement
- (D) It secretes digestive enzymes
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Answer: A – Coordination centres, such as the brain, spinal cord and pancreas, receive and process information from receptors.
Q6. Which of these is an effector?
- (A) A light receptor in the eye that detects changes in brightness and colour
- (B) A muscle that contracts to bring about a response
- (C) A sensory neurone
- (D) A temperature receptor in the skin
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Answer: B – Effectors are muscles or glands that bring about responses which restore optimum levels.
Q7. Which sequence correctly shows the stages of a control system?
- (A) Effector, receptor, coordination centre, response, with the response feeding back to the receptor
- (B) Response, stimulus, receptor, effector
- (C) Receptor, effector, stimulus, coordination centre
- (D) Stimulus, receptor, coordination centre, effector, response
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Answer: D – A stimulus is detected by a receptor, processed by a coordination centre, and acted on by an effector to give a response.
Q8. What is negative feedback?
- (A) A response that stops the control system working altogether so no further correction can happen
- (B) A response that makes a change larger and larger
- (C) A response that reverses a change and restores the normal level
- (D) A response that only works during sleep
Show Answer
Answer: C – Negative feedback reverses a change, bringing a condition back towards its normal level.
The Nervous System and Reflex Actions
Q9. What is the central nervous system (CNS) made up of?
- (A) The brain and spinal cord
- (B) The brain and the sense organs
- (C) All the muscles and glands
- (D) The sensory and motor neurones only
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Answer: A – The CNS is the brain and spinal cord, which coordinate the response of effectors.
Q10. How is information passed along neurones?
- (A) As hormones dissolved in the blood
- (B) As food molecules moving through the cytoplasm
- (C) As sound waves through tissue
- (D) As electrical impulses
Show Answer
Answer: D – Information from receptors passes along neurones as electrical impulses to the CNS.
Q11. Which neurone carries impulses from a receptor towards the CNS?
- (A) A motor neurone
- (B) A sensory neurone
- (C) A relay neurone in a muscle
- (D) An effector neurone
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Answer: B – Sensory neurones carry impulses from receptors to the CNS, while motor neurones carry impulses out to effectors.
Q12. What does the term synapse describe?
- (A) A type of muscle fibre that contracts when it receives an impulse from a motor neurone
- (B) A hormone-secreting gland
- (C) A gap between neurones across which a chemical transmitter passes
- (D) A receptor in the skin
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Answer: C – A synapse is a gap between neurones, and a chemical transmitter crosses it to trigger the next neurone.
Q13. What is a reflex action?
- (A) An automatic and rapid response that does not involve conscious thought
- (B) A slow response controlled only by hormones
- (C) A learned response that improves with practice over many weeks of training
- (D) A response that happens only in the brain
Show Answer
Answer: A – Reflex actions are automatic and rapid, and they do not involve the conscious part of the brain.
Q14. In a reflex arc, which neurone connects the sensory neurone to the motor neurone in the CNS?
- (A) A gland cell
- (B) A receptor cell
- (C) A muscle cell
- (D) A relay neurone
Show Answer
Answer: D – The relay neurone in the spinal cord or brain links the sensory neurone to the motor neurone in a reflex arc.
Q15. Why is a reflex action faster than a conscious response?
- (A) It uses hormones instead of electrical impulses, travelling slowly in the blood to reach distant target organs
- (B) The pathway is shorter because it passes through a relay neurone without conscious thought
- (C) It uses larger muscles
- (D) It bypasses the receptors entirely
Show Answer
Answer: B – The reflex pathway is short and does not involve conscious thought, so the response is rapid.
The Brain, the Eye and Body Temperature
Q16. Which part of the brain is mainly responsible for coordinating movement and balance?
- (A) The medulla
- (B) The spinal cord
- (C) The cerebellum
- (D) The retina
Show Answer
Answer: C – The cerebellum coordinates movement and balance, while the medulla controls unconscious actions such as heartbeat.
Q17. Which region of the brain is concerned with conscious thought, memory and language?
- (A) The cerebral cortex
- (B) The optic nerve
- (C) The cerebellum, which coordinates movement and balance
- (D) The lens
Show Answer
Answer: A – The cerebral cortex is the outer region of the brain associated with complex behaviour, including conscious thought and memory.
Q18. To focus on a near object, what happens in the eye?
- (A) The ciliary muscles relax and the lens becomes thin, which is what happens for a distant object
- (B) The pupil closes completely
- (C) The retina moves forward
- (D) The ciliary muscles contract, the suspensory ligaments loosen and the lens becomes thicker
Show Answer
Answer: D – For a near object, the ciliary muscles contract, the suspensory ligaments loosen, and the thicker lens refracts light more strongly.
Q19. What is myopia?
- (A) Long sightedness, where distant objects are blurred and near objects are seen clearly
- (B) Short sightedness, where light focuses in front of the retina
- (C) Colour blindness in dim light
- (D) Loss of hearing with age
Show Answer
Answer: B – In myopia, or short sightedness, rays of light do not focus on the retina, and near objects are seen more clearly than distant ones.
Q20. Where is body temperature monitored and controlled?
- (A) In the pancreas
- (B) In the skin alone, without any involvement of the brain or nervous system
- (C) In the thermoregulatory centre in the brain
- (D) In the adrenal glands
Show Answer
Answer: C – Body temperature is monitored and controlled by the thermoregulatory centre in the brain, which receives impulses from temperature receptors.
Hormones and Blood Glucose
Q21. How do hormones reach their target organs?
- (A) Along sensory neurones
- (B) Through the digestive system
- (C) Through air passages in the lungs during breathing and gas exchange
- (D) Carried in the bloodstream after secretion by glands
Show Answer
Answer: D – Endocrine glands secrete hormones directly into the bloodstream, and the blood carries each hormone to its target organ.
Q22. Compared with nervous responses, hormonal effects are usually what?
- (A) Slower but longer lasting
- (B) Faster but shorter lasting
- (C) Faster and longer lasting
- (D) Slower and shorter lasting
Show Answer
Answer: A – Compared with the nervous system, hormonal effects are slower but act for longer.
Q23. Which gland is described as a master gland because its hormones act on other glands?
- (A) The thyroid gland, which releases thyroxine to control metabolic rate
- (B) The pituitary gland in the brain
- (C) The adrenal gland
- (D) The pancreas
Show Answer
Answer: B – The pituitary gland in the brain secretes several hormones that act on other glands and stimulate them to release hormones.
Q24. When blood glucose concentration is too high, what does the pancreas do?
- (A) It stops producing all hormones
- (B) It releases glucagon to raise glucose further, which would make high blood glucose even higher
- (C) It produces insulin, which causes glucose to move into cells and be stored as glycogen
- (D) It converts glucose directly into urea
Show Answer
Answer: C – Insulin causes glucose to move from the blood into cells, and in liver and muscle cells excess glucose is converted to glycogen for storage.
Q25. What is type 1 diabetes?
- (A) A disorder in which the pancreas fails to produce sufficient insulin, so blood glucose stays high
- (B) A disorder in which the liver stores too much glycogen and cannot release glucose into the blood when it is needed
- (C) A disorder caused by excess adrenaline
- (D) A disorder in which the kidneys reabsorb too much water
Show Answer
Answer: A – In type 1 diabetes the pancreas fails to produce sufficient insulin, so blood glucose levels stay uncontrolled and high, and it is normally treated with insulin injections.
Q26. What happens in type 2 diabetes?
- (A) The thyroid gland stops working
- (B) The brain stops receiving impulses
- (C) The adrenal glands produce no hormones, including adrenaline, at any time
- (D) Body cells no longer respond properly to insulin produced by the pancreas
Show Answer
Answer: D – In type 2 diabetes the body cells no longer respond to insulin, and obesity is a risk factor; a carbohydrate controlled diet and exercise are common treatments.
Water Balance, Temperature Control and Plant Responses
Q27. What is the role of ADH in the body?
- (A) It increases sweating from glands in the skin, which would lose even more water from the body
- (B) It acts on the kidney tubules so more water is reabsorbed when blood is too concentrated
- (C) It converts glucose to glycogen
- (D) It dilates blood vessels in the skin
Show Answer
Answer: B – ADH is released by the pituitary gland when the blood is too concentrated, and it causes more water to be reabsorbed from the kidney tubules.
Q28. If body temperature is too high, which two responses help to cool the body?
- (A) Vasoconstriction and shivering
- (B) Sweating stops and muscles relax
- (C) Blood vessels dilate and sweat is produced
- (D) Hairs stand up and blood flow to the skin falls
Show Answer
Answer: C – When body temperature is too high, blood vessels dilate and sweat is produced, and both transfer energy from the skin to the environment.
Q29. How does auxin cause a shoot to bend towards light?
- (A) Auxin moves to the shaded side, where it speeds up growth, so the shoot bends towards light
- (B) Auxin blocks growth on the shaded side completely, so only the lit side grows longer and the shoot bends away
- (C) Auxin makes the whole shoot grow downwards
- (D) Auxin is destroyed by light on the shaded side only
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Answer: A – Auxin made in shoot tips moves to the shaded side, where it speeds up cell growth, so the shoot bends towards light.
Q30. Which statement about plant responses is correct?
- (A) Shoots bend towards gravity and roots bend away from it
- (B) Roots bend towards light and shoots bend away from it
- (C) Plant responses are controlled only by the nervous system
- (D) Shoots bend towards light and roots bend towards gravity
Show Answer
Answer: D – Plants respond to light and gravity: shoots bend towards light, while roots bend away from light and towards gravity.
Work through any questions you missed again, then revise those areas before moving on to the next topic.