IB Diploma Biology Practice Test

A sequence of organisms where each serves as a food source for the next is known as a food chain. A food chain is a linear representation of energy transfer through various trophic levels, beginning with primary producers (like plants or phytoplankton) and moving upwards through consumers (herbivores and carnivores) until reaching apex predators. Each step in the chain shows who eats whom, illustrating the direct feeding relationships among organisms.

In contrast, a food web consists of many interconnected food chains, representing a more complex network of energy transfer in an ecosystem. An energy cycle refers to the flow of energy through a system, while a nutrient cycle describes the movement and transformation of nutrients through biotic and abiotic components. The nature of the food chain emphasizes the direct succession of energy from one organism to another, highlighting the pathways of energy flow in an ecosystem.