Explain food chain with example.

A food chain is a simple representation of the flow of energy and nutrients through an ecosystem. It shows how different organisms are linked based on their feeding relationships. In a food chain, each organism serves as a source of food for the next organism in line. The chain typically starts with a primary producer, such as a plant or algae, and progresses through various levels of consumers.

Here's an example of a simple terrestrial food chain:

1.      Grass (Primary Producer): Grass is a primary producer that converts sunlight into energy through photosynthesis.

2.      Grasshopper (Primary Consumer): Grasshoppers are herbivores that eat grass.

3.      Bird (Secondary Consumer): Birds are carnivores that eat grasshoppers. 

4.      Snake (Tertiary Consumer): Snakes are predators that eat birds.

5.      Hawk (Apex Predator): Hawks are apex predators that feed on snakes.

Each step in the food chain represents a trophic level, which indicates an organism's position in the chain based on its feeding habits. Energy flows from one trophic level to the next as organisms are consumed.

It's important to note that most ecosystems are more complex than a simple linear food chain. In reality, food webs are more common, where multiple interconnected food chains overlap and interact. These webs reflect the complexity of ecological relationships and energy flow within an ecosystem.