Matter and Energy in Ecosystems
Aligned to HS-LS2-3 — Next Generation Science Standards.
What this lesson teaches
Ecosystems recycle matter while energy flows through only once. Aerobic conditions use oxygen to release energy efficiently; anaerobic conditions, lacking oxygen, release far less through fermentation.
Worked examples
Example 1
In waterlogged mud with no oxygen, bacteria ferment organic matter and release methane, transferring far less energy than the oxygen-rich decomposition happening on dry soil.
Example 2
Decomposers are not a footnote. Remove them and nutrients stay locked in dead tissue, and the producers starve.
Example 3
Matter cycles and energy does not. Carbon atoms return; the energy leaves as heat at every step and must be resupplied by sunlight.
Practice questions
- Compare the products of aerobic and anaerobic breakdown of organic matter.
- Trace one carbon atom through a food chain and back into the air.
- Explain why energy must keep entering an ecosystem but matter does not.
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Materia y energía en los ecosistemas
Los ecosistemas reciclan la materia, mientras que la energía los atraviesa una sola vez. Las condiciones aeróbicas usan oxígeno para liberar energía de forma eficiente; las condiciones anaeróbicas, sin oxígeno, liberan mucha menos energía mediante la fermentación.
Ejemplo 1: En el lodo encharcado sin oxígeno, las bacterias fermentan la materia orgánica y liberan metano, transfiriendo mucha menos energía que la descomposición rica en oxígeno que ocurre en el suelo seco.
Ejemplo 2: Los descomponedores no son una nota al pie. Quítalos y los nutrientes se quedan encerrados en tejido muerto, y los productores mueren de hambre.
Ejemplo 3: La materia circula y la energía no. Los átomos de carbono regresan; la energía se va como calor en cada paso y debe reponerse con luz solar.
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