Ecosystem
Definition
Components of Ecosystems
Oxford Languages
A biological community of interacting organisms and their physical environment.
Pearson Edexcel IGCSE
A distinct, self-supporting system of organisms interacting with each other and with a physical environment.
Producers
Plants which photosynthesise to produce food.
Consumers
Animals that eat plants or other animals.
Decomposers
Organisms that break down dead material and help to recycle nutrients.
The Physical Environment
All the non-biological components of the ecosystem.(i.e water and soil in a pond, soil and air in a forest)
Interactions in Ecosystems
Feeding among the organisms
Plants, animals, and decomposers are continually recycling the same nutrients through the ecosystem.
Competition among the organisms
Animals compete for food, shelter, mates, nesting sites. Plants compete for carbon dioxide (CO2), mineral ions, light and water.
Interactions between organisms and the environment
- Plants absorb mineral ions, carbon dioxide and water from the environment.
- Plants also give off water vapour and oxygen into the environment.
- Animals use materials from the environments to build shelters.
- Temperature of the environment can affect processes occurring in the organisms.
- Processes occurring in organisms can affect the temperature of the environment.
Food Chain
In any food chain, the arrow(-->) means 'is eaten by'.
In the illustration,
- The grass is the producer. It is a plant so it can photosynthesise and produce food materials.
- The grasshopper is the primary consumer. It is an animal which eats the producer and is also a herbivore.
- The lizard is the secondary consumer. It eats the primary consumer and is also a carnivore.
The different stages in a food chain (producer, primary consumer and secondary consumer) are called trophic levels.
Extra links after secondary consumer are called :
- Tertiary consumer : comes after secondary consumer
- Quaternary consumer : comes after tertiary consumer
Food Web
The range of food web is bigger than food chain. It consists of several food chains. Food web gives us much more information than food chains.
Ecological
Pyramids
There are 2 main types :
- Number Pyramids,
which represent the number of organisms in each trophic level in a food chain, irrespective of their mass.
Ecological pyramids are diagrams that represent the relative amounts of organisms at each trophic level in a food chain.
- Biomass Pyramids,
which show the total mass of the organisms in each trophic level, irrespective of their number.