IB Biology D3.3 Homeostasis: practice questions

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D3.3-01 · Paper 1A style · multiple choice · 1 mark

Feedback after a meal

After a meal, the blood glucose concentration of a person rises above the set point. Insulin secretion increases, the blood glucose concentration falls back towards the set point, and insulin secretion then decreases again.

Which type of feedback is shown, and what is the reason? [1]

1. Negative feedback, because insulin secretion falls as soon as blood glucose rises.
2. Positive feedback, because the rise in blood glucose causes insulin secretion to increase.
3. Negative feedback, because the response reverses the rise and decreases once the set point is restored.
4. Positive feedback, because the response moves blood glucose further from the set point.

Show the answer and the reasoning

Answer: C. C is correct. The rise in blood glucose triggers a response, insulin secretion, that brings the concentration back down; once the set point is restored the stimulus has gone and secretion falls. A response that opposes the original change is negative feedback, and it works from above or below the set point, which is why homeostasis relies on it. A gets the insulin response backwards: secretion rises when blood glucose is high. B treats any stimulus that increases a response as positive feedback; positive feedback would mean the response pushed blood glucose even higher. D describes positive feedback correctly, but the stem shows the concentration returning to the set point, not moving away from it.

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The 5 questions in D3.3

1. D3.3-01 Feedback after a mealPaper 1A style · multiple choice · 1 mark
2. D3.3-02 Correcting low blood glucosePaper 1A style · multiple choice · 1 mark
3. D3.3-03 Producing heat in the coldPaper 1A style · multiple choice · 1 mark
4. D3.3-04 Filtrate to urinePaper 2 style · short answer · 7 marks · HL
5. D3.3-05 Holding the set pointPaper 2 style · extended response · 15 marks

More of D Continuity and change

• D1.1 DNA replication
• D1.2 Protein synthesis
• D1.3 Mutation and gene editing
• D2.1 Cell and nuclear division
• D2.2 Gene expression
• D2.3 Water potential
• D3.1 Reproduction
• D3.2 Inheritance
• D4.1 Natural selection
• D4.2 Stability and change
• D4.3 Climate change

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Every Biology and Chemistry question here is original, written for practice in the style of the papers set since the 2025 syllabus, with invented data. Developed independently from the International Baccalaureate Organization, which has not endorsed it. Found a mistake? Email vytis@limeadmissions.com with the question id.