What is a food chain?

• A. A simple diagram showing who eats whom in an ecosystem with energy flowing from producers to consumers
• B. A complex network showing all energy pathways in an ecosystem
• C. A chart of all plants in an area
• D. A model of predator-prey cycles only

Answer: (A)

A food chain is a simple diagram that shows who eats whom in an ecosystem and how energy moves from producers to consumers. It starts with producers, organisms that capture energy from the sun, like plants or algae. Primary consumers eat those producers, secondary consumers eat the primary ones, and so on. Energy flows up the chain in one direction and becomes less as it’s transferred between levels.

This idea is different from a food web, which maps many feeding relationships in a more complex network. Other options describe things that aren’t about a single, linear transfer of energy—for example, a chart of all plants, a network of all energy pathways, or a model focusing only on predator–prey cycles.