Final answer:
A food chain is a sequence of organisms where each organism relies on the one below it for energy in an ecosystem.
Step-by-step explanation:
A food chain is a sequence of organisms in an ecosystem where each organism depends on the one below it for energy. It starts with a primary producer, usually a plant, which converts sunlight into energy through photosynthesis. The primary producer is then consumed by a primary consumer, such as an herbivore, which is then eaten by a secondary consumer, such as a carnivore. This sequence continues with tertiary consumers and so on. For example, in a forest ecosystem, the food chain could start with grass as the primary producer, followed by a mouse as the primary consumer, a snake as the secondary consumer, and finally a hawk as the tertiary consumer.
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