Students should be able to explain the importance of sugars, amino acids, fatty acids and glycerol in the synthesis and breakdown of carbohydrates, proteins and lipids.

Metabolism is the sum of all the reactions in a cell or the body.

The energy transferred by respiration in cells is used by the organism for the continual enzyme controlled processes of metabolism that synthesise new molecules.

Metabolism includes:

  • conversion of glucose to starch, glycogen and cellulose
  • the formation of lipid molecules from a molecule of glycerol and three molecules of fatty acids
  • the use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins
  • respiration
  • breakdown of excess proteins to form urea for excretion.
  • All of these aspects are covered in more detail in the relevant specification section but are linked together here.