What is a food chain?

A food chain is fundamentally defined as a sequence of organisms where each organism serves as a source of food for the next in line. This definition highlights the linear relationship between different organisms in an ecosystem, illustrating how energy and nutrients flow from one organism to another. Starting with producers, like plants that convert sunlight into energy through photosynthesis, the food chain progresses through various levels of consumers, such as herbivores that eat plants and carnivores that consume other animals.

Understanding this concept helps illustrate the interconnectedness of life in an ecosystem and how the survival of one species is often reliant on another. In a well-functioning ecosystem, this chain ensures that energy is transferred and that populations are balanced.

While other options present relevant concepts—like predator-prey relationships, lists of food items, or energy cycles—they do not accurately capture the essence of a food chain as a direct, linear progression of energy transfer from one organism to the next. Each of these elements plays a role in understanding ecology but does not define a food chain as precisely as option A does.