An ecosystem diagram. Image credit

An ecosystem diagram. Image credit

ZIMSEC O Level Combined Science Notes: Ecosystems


  • Is a self-contained system of interdependent organisms and their physical environment
  • An ecosystem can also be defined as a biological community of interacting organisms and their physical environment.
  • In an ecosystem a community of living organisms lives in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system.
  • For example in a typical grassland ecosystem the grasses/plants and animals depend on each other
  • They also depend on the soil, air and water in that area
  • The plants and animals live under certain conditions
  • The plants grow because they have the right amount of rainfall, light, air and soil conditions that suit them
  • The animals live there because they have the right kind of food to eat and shelter to live
  • The organisms (plants and animals) depend on each other and on their surroundings
  • The surroundings usually act as a source of energy
  • The plants and animals that are interdependent under a given set of conditions form the ecosystem
  • Zimbabwe has a variety of ecosystems for example forest, lake, river and grassland ecosystems
Energy transfer in an ecosystem

Energy transfer in an ecosystem

  • Every ecosystem depends on the energy from the sun
  • The plants use solar energy to create food using the photosynthesis process
  • The energy is stored/trapped in the plants until they are eaten by the animals
  • Thus energy flows in an ecosystem as it is transferred from the plants to the animals for example
  • The flow of energy is critical as it ensures a balanced ecosystem is maintained
  • There must be adequate transfer of energy from the sun, to the plants and to the animals
  • This balance can be easily upset by the interference of humans
  • Typically the environmental conditions in an ecosystem include the air, water, light and heat energy
  • The soil also has some physical properties such as its texture
  • Soils have living organisms in them as well as organic matter
  • These are biological components of an ecosystem
  • The biological components of an ecosystem (plants and animals) interact with one another

To access more topics go to the Combined Science Notes page.

Quick NetOne, Econet, And Telecel Airtime Recharge