Zooplankton: They are primary consumers in an aquatic food chain who feeds upon phytoplanktons.

Atmosphere supplies CO₂ and O₂ to most organisms and moisture to some organisms; lithosphere provides water and minerals; and hydrosphere gives water and some dissolved minerals.

Humification is the process by which detritus is changed into dark-colored amorphous substance called humus which acts as a reservoir of nutrients, while mineralisation involves the release of inorganic substances .

Ecological pyramids are the graphical representation of ecological parameter. These are characterized by pyramid of number, pyramid of mass and pyramid of energy in an ecosystems. Assumption of a simple food chain is the major shortcoming of ecological pyramids.
If we do not provide food web, clear position the trophic levels of an organisms cannot be given. Saprophytic organisms are not given any place in the ecological pyramid, though they are the important component in an ecosystem.

Sometimes climax remains in a particular seral stage without reaching the climax because during ecological succession any change in the abiotic and biotic component may affect the particular seral stage, leading to the preclimax stage before the climax is achieved.
This type of condition occurs presence of seeds and other propagules. This secondarily based area may be invaded by moss or exotic weeds thus exhibiting succession seriously and the climax community is never regenerated. In the case of natural calamities like fire lanslide, floods, change in soil texture.

Primary productivity depends upon the producers (plants species) their photosynthetic potential, soil, climate and other environmental factors of an ecosystem. They are seldom similar in different ecosystem. Therefore, primary productivity varies from ecosystem to ecosystem.

Passage of food energy from lower trophic level to higher trophic level follows 10% law. The rest of the energy is dissipated. Lion feeds on deer (lower trophic level). So 10kg of meat of deer will form only 1kg of lion's flesh. The rest of the food energy present in deer's meat is wasted and dissipated.

1. The microbes are also heterotrophs.
2. Those microbes which meet their energy requirement by degrading the dead and decaying organic matter,are called decomposers.
3. Those microbes which depend on living organisms for their food as well as shelter, are called parasites.

1. The rate of decomposition is regulated by temperature and soil moisture, as they influence the activities of decomposers.
2. The trophic have a warm/hot and humid condition; such a condition is favourable for the decomposers and hence they speed up the process of decomposition.