BioenergeticsRequired Practical
Required Practical: Effect of Temperature on Respiration Rate
Part of Respiration — GCSE Biology
This required practical covers Required Practical: Effect of Temperature on Respiration Rate within Respiration for GCSE Biology. Topic 2: Respiration It is section 6 of 15 in this topic. Revise both the method and the reason for each step, because practical questions often test understanding rather than pure recall.
Topic position
Section 6 of 15
Practice
15 questions
Recall
20 flashcards
🧪 Required Practical: Effect of Temperature on Respiration Rate
Method
- Add yeast suspension and glucose solution to a boiling tube
- Place the tube in a water bath set to a specific temperature (e.g. 20°C)
- Attach a delivery tube leading to a test tube of limewater (or use a gas syringe to collect CO₂)
- Start a timer and count the number of CO₂ bubbles produced in 5 minutes (or measure volume of gas collected)
- Repeat at different temperatures (e.g. 20°C, 30°C, 40°C, 50°C, 60°C)
- Repeat each temperature 3 times and calculate a mean
Key Variables
- Independent variable: Temperature of the water bath
- Dependent variable: Volume of CO₂ produced (or number of bubbles per minute)
- Control variables: Volume and concentration of glucose solution, amount of yeast, time measured
Expected Results
Rate of respiration increases as temperature rises (more kinetic energy → more enzyme-substrate collisions). Above the optimum (~40°C), rate drops sharply as enzymes denature. At 60°C, little or no CO₂ is produced.
Common Exam Errors
- Saying enzymes "die" at high temperatures — enzymes are not alive, they denature
- Forgetting to mention that repeats are needed to calculate a reliable mean
- Not identifying the control variables when asked