The smallest amount of energy transferred is represented by arrow 2 and largest energy loss by arrow 3.

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.

Life occurs from about 9000 metres down in the oceans to about 15000 metres up in the air. Thus, the biosphere has a total vertical extent of 2400 metres, or 24 kilometres.

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.

Primary source of energy is sun.This solar energy is first trapped by the green plants, called producers, and is used to assimilate organic food by the process of photosynthesis. This food energy of the producers is transferred to the herbivores (primary consumers) and then to different types of carnivores because all the consumers are heterotrophs. The energy can not be transferred from consumers to producers and from the producers to sun. So there is producers and from the producers and from the producers and from the producers to sun. So there is always unidirectional flow of energy which is accompanied with decrease in usable energy.

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.