Functions of Life

Functions of Life


  • Each structure in the body carries out functions necessary for life.
  • These functions can be grouped into 6 categories:
    1. Organization
    2. Metabolism
    3. Responsiveness
    4. Movement
    5. Development
    6. Reproduction


  • For the body to function effectively there must be organization and separation.
  • For example, blood will only flow if it is kept inside your circulatory system.
  • The integumentary system, which includes the skin, hair, nails and exocrine glands, functions as a barrier. It separates our internal organs from potentially harmful toxins in the external environment.
  • Organization can also be found at the microscopic level, with the cell membrane acting as a barrier between the intracellular environment separate from the extracellular environment.


  • Metabolism is the process of consuming food and using it for energy and maintenance.
  • It is made up of two types of reactions:
    • Anabolism
      • This is the process of combining small molecules into larger ones.
      • It requires energy.
      • The result of anabolism is usually referred to as a 'macromolecule'.
    • Catabolism
      • This is the process of breaking down large molecules into smaller ones.
      • It releases energy.
  • adenosine triphosphate (ATP) is a chemical compound used by cells to store and release energy.
    • The cell uses anabolism to synthesize ATP, this stores energy
    • ATP molecules can then be moved to where they are needed
    • The cell then uses catabolism to break down the ATP and release energy


  • Responsiveness can be split into internal and external.
  • Internal:
    • E.g. sweating in response to increased body temperature.
  • External:
    • E.g. moving towards sources of food and water, or moving away from danger.


  • Movement can be found at all the levels of organization:
    • Movement of water, carbon dioxide, and other molecules
    • Movement of cells (blood, for example) through the body
    • Movement of tissues, such as muscle contraction
    • Movement of organs, and organ systems, e.g. to move food through your digestive system
    • Movement of an entire organism, e.g. walking or running


  • Development encompasses changes in the body, such as:
    • Renewal
    • Differentiation
      • A cell changing from one type to another (usually a more specialized type)
    • Growth
      • An increase in the total number of cells
      • An increase in the size of existing cells
      • An increase in non-cellular molecules
        • For example, storing minerals in bones


  • The creation of new organisms from their parents.