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Energy for Biological Processes

Measuring respiration with a respirometer

  • 2 things to know
  • Papers 1 and 3

Overview

Recall questions on how a respirometer measures respiration, carbon dioxide absorbents, the control tube and equilibration, the variables to investigate and control, calculating rate from fluid movement, adapting it for anaerobic respiration, and the safe and ethical use of organisms.

What you need to know

Answer each one before you reveal it.

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Key term

When investigating anaerobic respiration using a respirometer, why might the absorbent be omitted or the setup modified?

Process

State one safety precaution when using potassium hydroxide in a respirometer experiment.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What does a respirometer measure?

    Model answer

    The rate of respiration, by detecting changes in gas volume as oxygen is consumed or carbon dioxide is produced.

  2. 2

    Why is a carbon dioxide absorbent used in a respirometer when investigating aerobic respiration?

    Model answer

    So that volume changes reflect only oxygen uptake.

  3. 3

    Name two substances that can be used as carbon dioxide absorbents in a respirometer.

    Model answer

    Potassium hydroxide or soda lime.

  4. 4

    When setting up a respirometer to measure aerobic respiration, what absorbent should be included and why?

    Model answer

    A carbon dioxide absorbent such as potassium hydroxide or soda lime, so that volume changes reflect only oxygen consumption.

  5. 5

    State three factors that can be investigated using a respirometer.

    Model answer

    Temperature, substrate availability, and type of organism.

  6. 6

    List four control variables that should be maintained in respirometer experiments.

    Model answer

    Temperature, volume of organisms, equilibration time, and ensuring the apparatus is airtight.

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