Energy Systems

Question 1

What are the 3 energy systems?

Answer 1

ATP/PC (alactacid) system
Lactic Acidosis system
Aerobic System

Question 2

What is the enzyme that breaks down ATP in the first stage of the ATP/PC system?

Answer 2

ATPase

Question 3

Explain the first stage of the ATP/PC system

Answer 3

ATP —(ATPase)—> ADP + Pi + free energy

Question 4

Explain an endothermic reaction

Answer 4

a process or reaction in which the system absorbs energy from its surroundings

Question 5

Explain an exothermic reaction

Answer 5

a chemical reaction that releases energy by light or heat

Question 6

Explain a coupled reaction

Answer 6

In a coupled reaction energy required by 1 process is supplied by another process (final stage of ATP/PC system)

Question 7

Explain the second stage of the ATP/PC system

Answer 7

PC —(creatine kinase)—> Pi + C —> free energy

Question 8

Explain the third and final stage of the ATP/PC system

Answer 8

Energy (borrowed from the second stage) + ADP (borrowed from the first stage) —> ATP (re-synthesised)

Question 9

What is the energy yield of the ATP/PC system and explain whether it is positive or negative

Answer 9

1:1 - for every 1 creatine phosphate there is 1 ATP. Negative because it is inefficient and is a low yield

Question 10

What bi-products does each system produce?

Answer 10

ATP/PC system = none
Lactic Acid system = lactic acid
Aerobic system = none that are harmful BUT water is one

Question 11

What duration does each system last for? (Approx.)

Answer 11

ATP/PC = max. 10 seconds
Lactic acid = max. 3 minutes
Aerobic = max. Hours

Question 12

Where does each system occur?

Answer 12

Muscle sarcoplasm

Question 13

Explain the Lactic Acid system

Answer 13

Carbohydrates in food are broken down into glycogen which is further broken into glucose (by glycogen phosphorylase) which is then broken down again into pyruvic acid (by PFK). Due to the lack of oxygen this acid is converted into lactic acid (by lactate dehydrogenase)

Question 14

Explain the Aerobic Glycolysis (first stage) of the Aerobic energy system

Answer 14

It is the same as the lactic acid system BUT oxygen IS PRESENT therefore the pyruvic acid is converted into acetyl CoA. Instead of remaining in the sarcoplasm the CoA diffuses into the mitochondria leading to the second phase

Question 15

Explain the Krebs Cycle (second stage) of the Aerobic energy system

Answer 15

A number of chemical reactions take place here and the results are:

(a) Acetyl CoA + oxaloacetic acid - converts CoA into citric acid
(b) CO2 is produced, then removed via expiration
(c) Hydrogen is produced which goes to the electron transport chain
(d) Enough energy is released to re-synthesise 2 ATP’s

Question 16

Explain the Electron Transport Chain (third stage) of the Aerobic Energy system

Answer 16

The hydrogen produced in the Krebs cycle is carried into the electron transport chain where electrons are removed from the hydrogen creating enough energy to re-synthesise 34 ATP’s. Water is also produced as a by-product – easily removed by expiration

Question 17

List some pros and cons of the Lactic Acid System

Answer 17

Pros:- Higher yield than ATP/PC system - it has a 1:2 yield
- Fewer reactions means quicker re-synthesis of ATP
- longer duration than ATP/PC system (up to 3 mins)
Cons:- Lactic Acid is a by-product

Question 18

List some pros and cons of the Aerobic energy system

Answer 18

Pros:- Large energy yield - 1:38
- Long duration - up to multiple hours
- no harmful by-products
Cons:- low/moderate intensity
- Delay - it’s a longer process