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CAIE IGCSE Biology 12.1.2 Temperature & Respiration

Practise investigating how temperature changes respiration rate in yeast and seeds using gas-volume data, graphs and respirometers.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • calculate respiration rate from a graph gradient or gas-volume change over time
  • predict increasing rate towards an optimum, followed by a fall as enzymes denature
  • explain low-temperature results using kinetic energy and fewer effective collisions

12.1.2—Effect of temperature on respiration question 1

[Maximum number: 1]

One problem with using biomass in the process shown in Fig. 4.1 is that the breakdown stage produces a sugar called xylose and ethanoic acid. Yeast cannot use xylose, and ethanoic acid is toxic to yeast.

Scientists genetically engineered a type of yeast that can use xylose and ethanoic acid.
Fig. 4.2 shows the results of one of the trial experiments done by the scientists using their new genetically engineered yeast.

Fig. 4.2

Fig. 4.2

The experiment was done at 30∘C30^{\circ} \mathrm{C}.

The scientists repeated the experiment at 20∘C20^{\circ} \mathrm{C}.
Predict the results that you would expect for the concentration of ethanol.

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