Cell respiration

Nature of science:

Assessing the ethics of scientific research—the use of invertebrates in respirometer experiments has ethical implications. (4.5)

• Cell respiration is the controlled release of energy from organic compounds to produce ATP.
• ATP from cell respiration is immediately available as a source of energy in the cell.
• Anaerobic cell respiration gives a small yield of ATP from glucose.
• Aerobic cell respiration requires oxygen and gives a large yield of ATP from glucose.

Applications and skills:

• Application: Use of anaerobic cell respiration in yeasts to produce ethanol and carbon dioxide in baking.
• Application: Lactate production in humans when anaerobic respiration is used to maximize the power of muscle contractions.
• Skill: Analysis of results from experiments involving measurement of respiration rates in germinating seeds or invertebrates using a respirometer.

Guidance:

• Details of the metabolic pathways of cell respiration are not needed but the substrates and final waste products should be known.
• There are many simple respirometers which could be used. Students are expected to know that an alkali is used to absorb CO2, so reductions in volume are due to oxygen use. Temperature should be kept constant to avoid volume changes due to temperature fluctuations.

• Aim 8: The ethics of the use of animals in experiments could be discussed in relation to respirometer experiments. Large-scale use of food plants for biofuels and the resulting impact on food prices has ethical implications.