Unit 1.1c - energy for exercise

Question 1

The ATP-PC energy system can be used to resynthesise ATP.
Identify the ATP yield of the ATP-PC system.
Give a practical example from sport in which the ATP-PC system is predominantly used. (2)

Answer 1

Yield:
- 1ATP per PC/ 1:1

Example:
- long jump/ gymnastic vault/ 60-100m sprint/ sprint into the box in football

Question 2

Describe the following stages of the aerobic energy system: (6)

• Krebs cycle (also known as the citric acid cycle)
• Electron transport chain

Answer 2

Krebs cycle:
- Acetyl coenzyme A combines with oxaloacetic acid/oxaloacetate or acetyl CoA/ pyruvic acid forms citric acid/
citrate
- (site) matrix of the mitochondria
- Citric acid is oxidised/ hydrogen removed/ dehydrogenated
- (yield) 2 ATP resynthesised
- (by-products) CO2 released or H/ Hydrogen (atoms) released (into ETC)

Electron transport chain:
- Oxidation/ reduction of NAD/ FAD
- Hydrogen split into hydrogen ions (protons and electrons) or hydrogen is carried through the ETC
- (site) cristae of the mitochondria
- (yield) 34 ATP resynthesised or 1:34 yield or NAD 30ATP and FAD 4ATP
- (by-products) H2O/ water

Question 3

Two performers run one lap of a 400 m track. One performer jogs around the track; the other performer sprints around the track.
Using knowledge of the recovery process, explain why it takes longer for the performer who sprints to recover (3)

Answer 3

• Sprinting/high intensity anaerobic work increases oxygen deficit
• Sprinting/ high intensity anaerobic work produces lactic acid/ lactate production
• (which) sprint has a greater EPOC or sprint has longer lactacid phase
• (RR/HR) Respiratory/ heart rates/ metabolic rate stays above resting levels for longer
• (oxygen) needs more O2/ aerobic energy produced in recovery to replenish oxymyoglobin/ resynthesise ATP/PC stores/ oxidise lactic acid

Question 4

Identify the processes that occur during the fast component of excess post exercise oxygen consumption (EPOC). (2)

Answer 4

• (Oxygen) Replenish/restore/re-link blood/haemoglobin/muscle/myoglobin
  with oxygen (replenishment of myoglobin with oxygen)
• (ATP) Resynthesise/replenish ATP (in the muscle)
• (PC) Resynthesise/replenish phosphocreatine/PC or Restore (muscle) phosphagen

Question 5

Explain how the aerobic system provides energy during a marathon (10)

Answer 5

1. Glycolysis
   - glycogen/glucose broken down to pyruvate
   - in the sarcoplasm
   - enzymes – Glycogen phosphorylase (GP) / phosphofructokinase (PFK)
   - 2 ATP produced.
2. Pyruvate is converted in the link reaction
   - into acetyl co-enzyme A/CoA
   - which enters the Kreb’s cycle/citric acid cycle.
3. (acetyl CoA)
   - combines with oxaloacetic acid
   - to form citric acid/cyclical set of reactions
   - in (matrix of) mitochondria
   - 2 ATP produced
   - carbon dioxide released (and expired)
   - hydrogen produced (which enters ETC).
4. (Fats)
   - fatty acids also used as fuel
   - beta-oxidation
   - much larger amounts of ATP produced (dependent on type of fat).
5. (ETC)
   - (hydrogen enters) electron transport/transfer chain
   - (hydrogen carried by) carrier molecules / NADs and FADs
   - to cristae (of mitochondria)
   - (where H is split into) H+/protons/ions and electrons
   - H+ combines with oxygen to produce water
   - 34 ATP produced / 38 ATP in total.
6. (effect of fitness)
   Aerobic capacity is very high (which means):
   - runner is able to use more fats as fuel
   because he can get more oxygen to the muscles
   - fats need more oxygen to metabolise/break down for energy
   - runner can conserve stores of glycogen.