explain using example the meaning of a food chain

FOOD CHAINS
A food chain is a linear feeding relationship between producers and consumers in an ecosystem. It represents the transfer of food energy from green plants through repeated stages of eating and being eaten.
There are two types of food chains
1. Grazing food chain. Starts with green plants
2. Detritus food chain. Starts with dead organic material (debris or detritus)

In construction of food chain, an arrow is used to link the different levels of organisms and the direction in which the arrow point is from the organism that is being consumed to the next consumer.
Examples
1. Water weeds tilapia nile parch crocodiles bacteria.
2. Plant debris bacteria protozoa mosquito larva

From one level to the next food energy is being transferred.
These different levels are referred to as energy levels/trophic levels. At various consumer levels, some of the food energy is utilized for respiration, while some of the energy is lost in form of heat through various processes such as;
1. urination
2. sweat
3. Panting.
4. Exhalation.
Therefore the amount of energy gained by the higher trophic levels keeps on decreasing such that at the final level (decomposers) the amount of energy is negligible.