The Need for Digestion (WJEC GCSE Biology)

The Need for Digestion

• The digestive system is an example of an organ system in which several organs work together to digest and absorb food

• Digestion is a process in which relatively large, insoluble molecules in food (such as starch, proteins) are broken down into smaller, soluble molecules that can be absorbed into the bloodstream and delivered to cells in the body

• These small soluble molecules (such as glucose and amino acids) are used either to provide cells with energy (via respiration), or with materials with which they can build other molecules to grow, repair and function

The products of digestion

• Some examples of how these food molecules are broken down during digestion are:

  • Insoluble fats are broken down to the soluble products of one glycerol molecule and three fatty acid chains

  • Insoluble proteins are broken down to soluble amino acids

  • Large insoluble carbohydrates, such as starch, can be broken down to soluble simple sugars

    • An example of a simple sugar is glucose