The Role of Microorganisms (Edexcel International A Level Biology): Revision Note

Microorganisms & Decay

• Dead plants and animals are broken down by microorganisms such as bacteria and fungi

  • These organisms are known as decomposers

  • They play an important role in recycling the chemical components needed by living organisms

• These decomposers secrete enzymes that break large organic molecules, such as cellulose, down into smaller ones

  • These small molecules, such as glucose, can be broken down further during respiration

  • During decomposition they also release waste products which provides nutrients to plants

• The microorganisms involved in decomposition produce CO₂ and methane which are released into the atmosphere

• Carbon dioxide can then be absorbed by green plants which will fix the carbon back into carbohydrates during photosynthesis

Microorganisms use biological molecules within dead tissue to fuel their respiration, releasing carbon back into the atmosphere in the process