• Aerobic?respiration requires?oxygen
  • It is defined as?the chemical reaction in cells that uses oxygen to break down nutrient molecules to release energy

   

• Aerobic respiration is the?complete breakdown of glucose?to release a relatively?large?amount of?energy?for use in cell processes and reactions
• Carbon dioxide and water?are produced as waste products as well as releasing useful cellular energy

Word equation for aerobic respiration

• This equation can also be shown as a?balanced chemical equation
  • One?molecule of glucose combines with?six?molecules of oxygen to produce?six?molecules of carbon dioxide and?six?molecules of water

   

The balanced symbol equation for aerobic respiration

• Anaerobic?respiration does?not require oxygen
  • It is defined as the chemical reaction in cells that breaks down nutrient molecules to release energy?without using oxygen

   

• It involves the?incomplete breakdown of glucose?and so releases a relatively?small?amount of?energy?for use in cell processes
• Different breakdown products are formed depending on the type of organism that the anaerobic respiration is taking place in
• You need to know the equations for anaerobic respiration in?animals?and?plants (or fungi)

Anaerobic respiration in animals

• Anaerobic respiration mainly takes place in muscle cells during vigorous exercise
• When we exercise at high intensities, our muscles have a?higher demand for energy
• Our bodies can only deliver so much oxygen to our muscle cells for aerobic respiration
• When oxygen runs out, glucose is broken down without it, producing?lactic acid?instead
• Glucose has not been fully broken down meaning there is still energy stored within the bonds of lactic acid molecules
• Anaerobic respiration releases less energy than aerobic respiration

Word equation for anaerobic respiration in animals

• This equation can also be shown as a balanced chemical equation
  • One?molecule of glucose is broken down into?two?molecules of lactic acid

   

The balanced chemical equation for anaerobic respiration in animals

Lactic acid and oxygen debt

• Lactic acid?builds up in muscle cells and?lowers the pH?of the muscle tissue (making the conditions more acidic)
  • Acidic conditions can?denature the enzymes in cells

   

• Lactic acid will eventually be broken down using?oxygen?to produce?carbon dioxide?and?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'
• The process of breaking down the lactic acid is known as?‘repaying the oxygen debt’

Anaerobic respiration in plants and fungi

• Plants and yeast can respire?without oxygen?as well, breaking down glucose in the absence of oxygen to produce?ethanol?and?carbon dioxide
• Anaerobic respiration in yeast cells is called?fermentation
• Fermentation is economically important in the manufacture of?bread?(where the carbon dioxide produced helps the dough to rise) and in?brewing?(where the ethanol produced makes beer)

Word equation for anaerobic respiration in plants and fungi

• This equation can also be shown as a?balanced chemical equation
  • One?molecule of glucose is broken down into?two?molecules of alcohol and?two?molecules of carbon dioxide

   

Balanced equation for anaerobic respiration in plants and yeast

• You need to be able to compare the processes of aerobic and anaerobic respiration with regard to the need for oxygen, the products and the relative amounts of energy transferred

Comparing Aerobic & Anaerobic Respiration Table

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