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Homeostasis Questions and Answers
Free GCSE Biology Revision Flashcards
Cover the principles of negative feedback and how the body maintains a stable internal environment, including temperature regulation, blood glucose control and kidney function.
Question
What is homeostasis?
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Answer
The maintenance of a stable internal environment within narrow limits despite changes in external conditions. Examples: body temperature, blood glucose, water balance.
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Question
What is a negative feedback loop?
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Answer
A control mechanism where a change from the set point triggers a response that reverses the change, restoring the original state. The basis of most homeostatic control systems.
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Question
What are the three components of a homeostatic control system?
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Answer
Receptor (detects change), control centre/coordinator (processes information and determines response — often the brain or endocrine gland), and effector (produces the corrective response — muscle or gland).
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Question
How does the body regulate blood glucose?
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Answer
After a meal, blood glucose rises → pancreatic beta cells secrete insulin → cells take up glucose, liver converts glucose to glycogen. If glucose falls → alpha cells secrete glucagon → liver converts glycogen back to glucose.
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Question
What is the role of insulin?
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Answer
Secreted by beta cells of the islets of Langerhans in the pancreas. Lowers blood glucose by promoting glucose uptake by cells and glycogenesis (glucose → glycogen) in the liver and muscle.
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Question
What is the role of glucagon?
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Answer
Secreted by alpha cells of the islets of Langerhans. Raises blood glucose by stimulating glycogenolysis (glycogen → glucose) and gluconeogenesis (making new glucose from non-carbohydrate sources) in the liver.
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Question
What is the difference between Type 1 and Type 2 diabetes in terms of homeostasis?
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Answer
Type 1: autoimmune destruction of beta cells → no insulin produced → uncontrolled high blood glucose. Type 2: cells become resistant to insulin → glucose uptake impaired → blood glucose remains elevated.
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Question
How does the body regulate temperature (thermoregulation)?
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Answer
The hypothalamus acts as the thermostat. If too hot: vasodilation, sweating, reduced metabolic rate. If too cold: vasoconstriction, shivering, raised metabolic rate, piloerection.
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Question
What is vasodilation?
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Answer
Widening of blood vessels near the skin surface — increases blood flow and heat loss by radiation. Occurs when the body is too hot.
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Question
What is vasoconstriction?
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Answer
Narrowing of blood vessels near the skin surface — reduces blood flow and heat loss. Occurs when the body is too cold to conserve heat.
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