Define the term oxygen deficit.

The oxygen deficit is the difference, at the start of exercise, between the oxygen actually consumed and the amount that would have been consumed had the demand been met aerobically from the first second.

State the key difference between the oxygen deficit and the oxygen debt.

The deficit builds up at the start of exercise and is oxygen that was not supplied, whereas the debt is consumed after exercise has stopped and is the extra oxygen taken in to restore the body to its resting state.

State three processes for which the oxygen of the oxygen debt is used.

Oxidising the lactate that has accumulated, resynthesising the creatine phosphate and ATP stores in the muscle, and resaturating the haemoglobin in the blood and the myoglobin in the muscle.

OCR A-Level Biology B H422

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Metabolism and Exercise

Oxygen deficit and oxygen debt

3 things to know
Components 01, 02 and 03

Overview

Recall questions on the oxygen deficit at the start of exercise and how ATP is supplied meanwhile, the oxygen debt and what its oxygen is used for, the fate of lactate, reaching a steady state, and how fitness and exercise intensity change the deficit and debt.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Explain why an oxygen deficit develops at the beginning of exercise.

Key term

Which two sources supply ATP while the oxygen deficit is building up?

Key term

Define the term oxygen debt.

Questions from this subtopic

Each one with the model answer underneath.

1
Define the term oxygen deficit.
Model answer
The oxygen deficit is the difference, at the start of exercise, between the oxygen actually consumed and the amount that would have been consumed had the demand been met aerobically from the first second.
2
Explain why an oxygen deficit develops at the beginning of exercise.
Model answer
Heart rate, breathing rate and blood redistribution take a minute or two to increase, so oxygen delivery lags behind the sudden rise in ATP demand and part of the ATP must be supplied anaerobically.
3
Which two sources supply ATP while the oxygen deficit is building up?
Model answer
Creatine phosphate stored in the muscle and anaerobic respiration through glycolysis.
4
Define the term oxygen debt.
Model answer
The oxygen debt, or excess post-exercise oxygen consumption, is the extra oxygen taken in above resting level after exercise has finished.
5
State the key difference between the oxygen deficit and the oxygen debt.
Model answer
The deficit builds up at the start of exercise and is oxygen that was not supplied, whereas the debt is consumed after exercise has stopped and is the extra oxygen taken in to restore the body to its resting state.
6
State three processes for which the oxygen of the oxygen debt is used.
Model answer
Oxidising the lactate that has accumulated, resynthesising the creatine phosphate and ATP stores in the muscle, and resaturating the haemoglobin in the blood and the myoglobin in the muscle.

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