Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test 2025 – All-in-One Study Guide for Exam Success!

A food chain primarily illustrates what each organism eats. It provides a linear representation of the flow of energy and nutrients through different levels of an ecosystem. In a food chain, organisms are linked based on their feeding relationships, starting with primary producers that capture energy from sunlight (like plants) and moving up to various consumers (herbivores, carnivores, and omnivores) that depend on other organisms for energy.

This illustration helps to clarify the relationships between different organisms and highlights the importance of each species within an ecosystem in sustaining the energy flow. Understanding a food chain can also provide insight into the effects of changes in population dynamics, such as the decline or increase of specific species and how this impacts the entire ecosystem.