2.8 Cell respiration

Teaching time: 3 hours                    Practical time: 0 hours

prior learning & retrieval practice

Essential idea: Cell respiration supplies energy for the functions of life.

U1: Cell respiration is the controlled release of energy from organic compounds to produce ATP.

U2: ATP from cell respiration is immediately available as a source of energy in the cell.

Guidance:

• Details of the metabolic pathways of cell respiration are not needed but the substrates and final waste products should be known.

Exercise 1: Answer the following questions:

• 1. What are the functions of life?

  2. What form is energy stored in in organic compounds?

  3. What form is it converted into in ATP?

  4. What makes energy in ATP immediately available to be used in the cell?

  5. How does energy become trapped in organic compounds?

A1: Use of anaerobic cell respiration in yeasts to produce ethanol and carbon dioxide in baking.

A2: Lactate production in humans when anaerobic respiration is used to maximize the power of muscle contractions.

U3: Anaerobic cell respiration gives a small yield of ATP from glucose.

Exercise 2: Draw a flow diagram of anaerobic respiration in the cell. Label the diagram to show where ATP is produced and what the substrates and end waste products are. Use different colours for each pathway.

U4: Aerobic cell respiration requires oxygen and gives a large yield of ATP from glucose.

Exercise 3: Draw a flow diagram of aerobic respiration in the cell. Label the diagram to show where ATP is produced and what the substrates and end waste products are. Use different colours for each pathway.

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

S1: Analysis of results from experiments involving measurement of respiration rates in germinating seeds or invertebrates using a respirometer.

Guidance:

• • 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.