CB8 - Exchange in animals - respiration

• What is respiration?

  An exothermic chemical reaction in cells that takes out energy from glucose and releases it along with carbon dioxide & water.
• Is respiration exothermic or endothermic?

  Exothermic - it transfers energy to the environment
• Give 3 examples of how cells use the energy from respiration

  ~ To build large molecules from smaller ones eg. Amino acids from proteins.

  ~ For muscle contraction - so we can move about.

  ~ To maintain body temperature - so we can stay warm in cold environments.
• What is metabolism?

  The combination of all chemical reactions in an organism.
• What is aerobic respiration?

  Respiration that takes place when theres enough oxygen.

  ~ Its the most efficient way to transfer energy from glucose and takes place continuously within mitochondria.
• Whats the word equation for aerobic respiration?

  glucose + oxygen --> carbon dioxide + water (+ energy)
• Whats the symbol equation for aerobic respiration?

  C6H12O6 + 6O2 → 6CO2 + 6H2O
• What is anaerobic respiration?


  The release of energy from glucose without using oxygen and happens when its necessary.
• When is anaerobic respiration necessary?


  When you sprint you can't get enough oxygen to the tissues to keep up w/ energy demands so anaerobic respiration occurs. Lactic acid increases the more you exercise.
• Whats the word equation for anaerobic respiration in animals?

  glucose --> lactic acid (+ energy)
• Whats the symbol equation for anaerobic respiration in animals?

  C6H12O6 --> 2C3H6O3
• Why is anaerobic respiration less efficient than aerobic respiration?

  ~ Theres an incomplete breakdown of glucose due to no oxygen oxidising it so not all the energy is released.

  ~ Lactic acid can be built up causing muscle cramps.
• How is lactic acid built up and what issues does it cause?

  Lactic acid builds up in muscle cells during exercise and lowers the pH of the muscle tissue (making the conditions more acidic)

  Acidic conditions can denature the enzymes in cells
• How is the lactic acid broken down again?

  Lactic acid will eventually be broken down using oxygen to produce CO2 & water as waste products.

  The amount of oxygen required to break down the lactic acid that has built up is referred to as the 'oxygen debt
• What is 'oxygen debt'?

  The amount of oxygen you would need to oxidise the lactic acid into carbon dioxide and water.
• Where else can anaerobic respiration take place?

  Plants and yeast cells?
• Whats anaerobic respiration called in yeast?

  Fermentation
• Whats the word equation for fermentation?

  Glucose --> ethanol + carbon dioxide
• Whats the symbol equation for fermentation?

  C6H12O6 --> 2C2H5OH + 2CO2
• How is fermentation used in the industry?

  ~ Yeast is used in bread as CO2 produced helps bread to rise.

  ~ In brewing where the ethanol produced makes beer