In any food chain,an average of $10 \%$ of the food eaten is turned into the body mass of an organism and made available for the next level of consumers.

Which group of organisms are not constituents of a food chain?
$(i)$ Grass,lion,rabbit,wolf
$(ii)$ Plankton,man,fish,grasshopper
$(iii)$ Wolf,grass,snake,tiger
$(iv)$ Frog,snake,eagle,grass,grasshopper

Which organisms perform photosynthesis to prepare food for themselves and other organisms?

In the given figure,the various trophic levels are shown in a pyramid. At which trophic level is maximum energy available?

Which organisms obtain nutrition from the dead bodies of plants and animals?

"Energy flow in a food chain is unidirectional." Justify this statement. Explain how the pesticides enter a food chain and subsequently get into our body.