• Key Words:

Less oxygen + less glucose to cells —>

1. Less aerobic respiration/energy released -> less muscle contractions —> reduced metabolism

   —> breathlessness/tiredness

2. More anaerobic respiration/lactic acid production -> build up causes muscle fatigue and pain + oxygen debt —> increased breathing rate

Anaerobic is less efficient = it is the incomplete breakdown of glucose which releases less energy and makes lactic acid which has to be transported by blood to liver (to be converted back to glucose)

Anaerobic respiration in plant and yeast cells

Fermentation: glucose → ethanol + carbon dioxide

Uses: Making bread rise, fermenting alcohol

Energy is for:

1. Muscle contractions / movement
2. Keeping a steady body temperature
3. Chemical reactions to build larger molecules (see below ⬇️)

<aside>

Metabolism uses enzymes for these chemical reactions:

1. Glucose —> starch, glycogen and cellulose
2. Glycerol + 3 molecules of fatty acids —> Lipids
3. Glucose + nitrate ions —> amino acids —> proteins
4. Glucose +Oxygen —> C02 + Oxygen (Respiration)
5. Breakdown of excess proteins to form urea for excretion </aside>

🧠 Exam-style questions

• Explain how taking anabolic steroids could improve an athlete’s performance (2)

https://www.exampaperspractice.co.uk/wp-content/uploads/Respiration.pdf – Respiration