Respiration- bio

• Respiration is the breakdown of food molecules with the release of energy in living cells
• Aerobic respiration:

  The chemical breakdown of food molecules in the presence of oxygen to release a large amount of energy

  • carbon dioxide and water are released as waste products 
  • Glucose + oxygen →carbon dioxide + water + large amount of energy (38 ATP)
  • C6H12O6 + 6O2 → 6CO2 + 6H2O + energy 
  • Examples:

  1. Muscular contractions
  2. Synthesis of proteins
  3. Cell division
  4. Active transport
  5. Synthesis of new cytoplasm
  6. Transmission of nerve impulses 
• Anaerobic respiration:

  The chemical breakdown of food molecules in the absence of oxygen

  • less energy is released

  In yeast:

  • also called alcoholic fermentation 
  • Glucose  → ethanol + carbon dioxide + small amount of energy (2 ATP)
  • C6H12O6 → 2C2H5OH + 2CO2 + energy 

  In muscle cells 

  • glucose → lactic acid + small amount of energy 
• Oxygen debt:

  • During vigorous muscular contractions, lactic acid builds up in the muscles and blood. 
  • Since there is insufficient oxygen to meet the demands of the vigorous muscular contractions, the muscles are said to incur an oxygen debt. 
  • After vigorous exercise, your breathing and heart rates continue to be fast for some time.
  • This is because, after vigorous exercise, the oxygen debt incurred has to be removed or repaid.
• How can oxygen debt (or lactic acid) be removed?

  • Continuation of deeper and faster breathing. This results in continued and fast intake of oxygen by the lungs. Sufficient oxygen is thus available for aerobic respiration. Lactic acid is broken down in the liver and energy is released.
  • Continuation of fast heart rate. This results in continued and fast transport of lactic acid from the muscles to the liver, and oxygen from the lungs to the liver.
• Similarities between aerobic and anaerobic respiration:

  1. Both release energy 
  2. Both involve the breakdown of food molecules
  3. Both require enzymes, this is because the chemical reactions involved in the breakdown of food molecules are catalysed by enzymes
• Differences between aerobic and anaerobic respiration:

  1. Aerobic respiration requires oxygen while anaerobic respiration does not
  2. Aerobic respiration releases a large amount of energy while anaerobic respiration releases a small amount of energy
  3. Aerobic respiration produces carbon dioxide and water while anaerobic respiration produces lactic acid in muscles and carbon dioxide and ethanol in yeast
• For experiment:

  • glucose solution is boiled first to get rid of impurities such as oxygen
  • The layer of oil is a barrier for oxygen