Paper 1 Advanced Info

Question 1

Where does the energy we use for muscle contractions come from?

Answer 1

Adenosine tri-phosphate (ATP): the only usable form of energy in the body.

Question 2

What are the three stages of the aerobic system?

Answer 2

1. Glycolysis
2. Krebs cycle
3. Electron transport chain

Question 3

What is the aerobic system?

Answer 3

• When exercise intensity is low and oxygen supply is high.

- E.g. jogging

Question 4

What happens during glycolysis?

Answer 4

• Breakdown of glucose into pyruvic acid in the sarcoplasm.
• For every molecule of glucose undergoing glycolysis, a net of two molecules of ATP is formed.
• Before the pyruvic acid produced in glycolysis can enter the next stage, it splits into two acetyl groups and is then carried into the Krebs cycle.

Question 5

What happens during the Krebs Cycle?

Answer 5

• Acetyl coenzyme A diffuses into the matrix of the mitochondria.
• This is where a series of cyclical chemical reactions in the cristae of the mitochondria occurs where hydrogen is oxidized to water and 34 molecules of ATP are produced.
• Citric acid is also formed which undergoes oxidative carboxylation where carbon and hydrogen are given off.
• The carbon forms carbon dioxide which is breathed out and the hydrogen is taken to the electron transport chain.

Question 6

What happens during the electron transport chain?

Answer 6

• Hydrogen is carried to the electron transport chain by hydrogen carriers.
• This occurs in the cristae of the mitochondria.
• The hydrogen splits into hydrogen ions and electrons and they are charged with potential energy.
• The hydrogen ions are oxidized to form water, while the hydrogen electrons provide the energy to re-synthesize ATP.
• This process forms 34 molecules of ATP.

Question 7

What is the ATP-PC system?

Answer 7

• An energy system using phosphocreatine (PC) as its fuel which is an energy-rich phosphate compound found in the sarcoplasm of muscles.
• It can be broken down quickly and easily to release energy to re-synthesise ATP.
• Rapidly available and is important for a single maximal effort or movement.

Question 8

How does the ATP-PC system provide energy?

Answer 8

• An anaerobic process which re-synthesizes ATP.
• It breaks down the phosphocreatine in the muscles to phosphate and creatine releasing energy:

Phosphocreatine(PC) –> Phosphate(Pi) + Creatine(C) + Energy

• This energy is then used to convert ADP to ATP in a coupled reaction:

Energy –> Pi + ADP –> ATP

Question 9

What is the anaerobic glycolytic system?

Answer 9

• Provides energy for high-intensity activity for longer than the ATP-PC system.
• This system can last up to 2-3 mins.

Question 10

How does the anaerobic glycolytic system work?

Answer 10

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