What is a food chain in science definition?

In science, a food chain is a sequence of organisms through which energy and nutrients pass. Each organism in the food chain occupies a specific trophic level, representing the position it holds in the sequence from producer to top consumer. The lowest trophic level consists of producers, such as plants, which synthesize food from inorganic molecules. Primary consumers are herbivores that feed directly on producers. Secondary consumers are carnivores that feed on primary consumers. Tertiary consumers are carnivores that feed on secondary consumers, and so on. This sequence of organisms creates a flow of energy and nutrients from lower to higher trophic levels. Energy is lost at each step of the food chain, as some energy is used for the organism's own metabolism and is not passed on to the next trophic level. As a result, the number of organisms decreases at each higher trophic level, forming a pyramid shape when represented graphically.