1. The producers(mainly green plants)convert light energy (sun)into chemical energy and store it as food during photosynthesis. Besides green plants, algae and certain bacteria can also photosynthesise and are producers. Producers are the only organism that can manufacture/produce complex organic food from inorganic raw materials.


2. Consumers(all animals)obtain their energy by feeding on other organisms. Plant-eaters(herbivores)feed directly from plants. Hence, they are known as primary consumers. Meat-eaters(carnivores)feed on other animals. Carnivores that feed on herbivores are know as secondary consumers those that feed on other carnivores are tertiary consumers.




3. picture of herivores(rabbit) and carnivores(lion).
   

3. Decomposers(fungi, bacteria, earthworms)obtain energy by breaking down dead organisms, faeces and excretory products. When the dead organisms and waste matter are broken down, the materials locked up in them are released. Thus, carbon and nitrogen compounds return to the physical environment and are used again by green plants.

Therefore, the energy and nutrients flow through an ecosystem starting from the producers(green plants)to the consumers(animals)and eventually to the decomposers(fungi, bacteria, earthworms)to break down waste matter which in turn could be used by the green plants and this will continue all over again.

An example of a food chain and food web is below:

• Food chain

green plant--->earthworms--->chicken--->snake

• Food web
  

Feeding relationships between organisms in an ecosystem can be represented using food chains. Each arrow means "is eaten by."

green plant----->earthworms----->chicken----->snake means green plant is eaten by earthworms, earthworms is eaten by chicken and the chicken is eaten by snake.

Each stage in a food chain is known as a trophic level. It generally doesn't have more than 4 levels.

Many food chains could be interlinked together to form a food web. In a food web, there may be 2 or more food chains.

Labels: pictures from www.flickr.com and www.wildlifetrust.org.uk