Higher levels of these chemicals are found in human beings because we occupy the top level in food chains, leading to the accumulation of the maximum concentration of these substances in our bodies.

Pesticides enter the food chain when they are washed into the soil or water bodies. Plants absorb them along with water and minerals, and they are then taken up by aquatic organisms, entering the ecosystem’s food chain.

Energy availability decreases at higher trophic levels because of the energy loss at each step, with only about 10% of the energy being transferred to the next level.

As energy moves through the various trophic levels, it diminishes progressively. This is due to the loss of energy at each level, mainly as heat.

The flow of energy in an ecosystem is unidirectional. Energy captured by autotrophs does not revert back to the sun, and energy passed to herbivores does not return to the autotrophs.