Necessary for movement, heat maintenance in mammals, and chemical reactions (e.g., building proteins from amino acids).
Supplied through cellular respiration.
Respiration Overview
Exothermic Reaction: Releases energy and occurs continually in living cells.
Two types of respiration: Aerobic and Anaerobic.
Aerobic Respiration
Process:
Glucose reacts with oxygen to produce carbon dioxide, water, and energy.
Word Equation: Glucose + Oxygen → Carbon Dioxide + Water + Energy
Key Fact: Releases a significant amount of energy because glucose is fully oxidized.
Chemical Symbols:
Glucose: C₆H₁₂O₆
Oxygen: O₂
Carbon Dioxide: CO₂
Water: H₂O
Anaerobic Respiration
Occurs when oxygen is limited.
In Muscle Cells
Process:
Glucose is converted to lactic acid.
Does not require oxygen.
Key Fact: Releases much less energy than aerobic respiration due to incomplete oxidation of glucose.
In Plant and Yeast Cells
Process:
Glucose is converted to ethanol and carbon dioxide.
No oxygen required.
Fermentation in yeast:
Useful for producing alcoholic drinks (e.g., beer) and bread.
Products:
Alcohol (ethanol) is produced by fermentation.
Carbon dioxide causes dough to rise.
Conclusion
Understanding of aerobic and anaerobic respiration is essential, especially distinguishing between energy outputs and conditions required for each type of respiration.
Further Study: Refer to the revision workbook for practice questions on respiration.