What does a food chain show and why it is important?

A food chain shows how energy is transferred from one living organism to another through food.

It is important because it shows the intricate relationships in ecosystems. It is seen that in food chains, each organism fills a specific niche in an ecosystem. Food chains reveal how each organism depends on someone else for survival.

Further Readings – 

1. Energy Flow in Ecosystem
2. Biodiversity – Species, Genetics & Ecosystem