Key learning points

1. Living yeast cells immobilised in alginate beads will carry out cellular respiration and produce carbon dioxide gas.
2. The gas can be collected and the volume of gas measured using an upturned measuring cylinder under water.
3. Identifying independent and dependent variables, and variables to control to increase the validity of the results.
4. How to read the volume of gas from the meniscus in the measuring cylinder after a set time.
5. Collecting repeat measurements for each substrate, and collecting data for different substrates.

Keywords

• Cellular respiration - An exothermic chemical process that transfers energy for life processes, using glucose as fuel.

• Independent variable - The factor that we change in an experiment.

• Dependent variable - The factor that we measure in an experiment.

• Random error - Causes results to differ by different amounts due to a factor other than the independent variable (the factor we changed).

• Systematic error - Causes measurements to differ from the true value by the same amount each time they are taken.

Common misconception