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Respiration

The need for respiration and glycolysis

  • 3 things to know
  • Component 1

Overview

What happens when triose phosphate is oxidised and number of carbon atoms in glucose, triose phosphate and pyruvate.

What you need to know

Answer each one before you reveal it.

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Key term

Why is the removal of hydrogen from a substrate described as oxidation?

Process

Why is the energy of glucose released in many small steps rather than all at once?

Key term

Describe what happens when triose phosphate is oxidised.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Define respiration.

    Model answer

    The enzyme-controlled release of energy from organic molecules in living cells, in a series of small steps, so that it can be captured as ATP.

  2. 2

    Why must every living cell respire continuously?

    Model answer

    Almost everything a cell does, from active transport and synthesis to movement and the maintenance of its own structure, needs ATP, and no cell holds more than a few seconds' supply.

  3. 3

    Why is the energy of glucose released in many small steps rather than all at once?

    Model answer

    A single large release would be lost mainly as heat and would damage the cell, whereas small steps release quantities that can be captured efficiently in ATP.

  4. 4

    Where in the cell does glycolysis take place?

    Model answer

    In the cytoplasm.

  5. 5

    Does glycolysis require oxygen?

    Model answer

    No, it proceeds whether or not oxygen is present, which is why it is common to both aerobic and anaerobic respiration.

  6. 6

    Explain why two molecules of ATP are used at the start of glycolysis.

    Model answer

    Their phosphate groups are added to the glucose to make hexose bisphosphate, which is more reactive and so lowers the activation energy for the reactions that follow.

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