Question 2
FA student investigated the energy released by respiring seeds. The student set up two vacuum flasks as shown in the figure. Flask A contained germinating seeds. Flask B contained seeds that had been boiled and then cooled. Both flasks were left in the same room for 4 days.
Figure: The two vacuum flasks used in the student's investigation
a.[1]
Give the independent variable in this investigation.
b.[1]
Both sets of seeds were washed in disinfectant before the investigation started. Suggest why.
c.[3]
After 4 days the temperature in flask A had risen by 8.5 °C. The temperature in flask B had not changed.
Explain these results.
d.[1]
Explain why a vacuum flask was used instead of a glass beaker.
e.[2]
The student repeated the investigation using twice the mass of germinating seeds in flask A. Suggest the effect this would have on the temperature reached in flask A after 4 days. Give a reason for your answer.
4.2 Respiration Questions
51 exam-style questions on AQA GCSE Biology 4.2 Respiration, covering 4.2.1 Aerobic and anaerobic respiration, 4.2.2 Response to exercise, and 4.2.3 Metabolism. Each one has a worked solution and a mark scheme showing where the marks go.