Ecosystems, Energy Flow and Matter Cycles
An ecosystem links organisms with the physical environment through transfers of energy and recycling of matter. This lesson distinguishes one-way energy flow from repeated movement of atoms and uses food webs to explain why changes can spread through a community.
Learning goals
- define the central terms precisely
- connect molecular, organismal and population evidence
- apply the ideas to unfamiliar biological cases
Core concepts
An ecosystem includes a community of organisms and the nonliving environment with which they exchange energy and matter.
A trophic level is a feeding position in an energy pathway, such as producer, primary consumer, or higher consumer.
A food web is a network of interconnected feeding relationships showing multiple pathways of energy transfer.
Energy enters most ecosystems as light, passes through organisms, and leaves as heat; it is not recycled like matter.
A decomposer obtains nutrients by breaking down dead organic material and returns mineral nutrients to the environment.
A biogeochemical cycle is the repeated movement of an element through organisms and the atmosphere, water, or rocks.
Concept map
Why these ideas matter
These concepts help scientists interpret evidence, design fair tests, communicate uncertainty, and make responsible decisions in research, health, agriculture, and environmental management.