7.2.2: How materials are cycled
Not started yet — this one needs some love.
Many different materials cycle through the abiotic and biotic components of an ecosystem.
All materials in the living world are recycled to provide the building blocks for future organisms.
Carbon cycle: returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis.
Water cycle: provides fresh water for plants and animals on land before draining into the seas.
Water is continuously evaporated and precipitated.
The nitrogen cycle is not required.
Microorganisms cycle materials by returning carbon to the atmosphere as carbon dioxide and mineral ions to the soil.
Common exam mistakes
Do not say energy or carbon is made in cycles; matter is recycled, while energy passes through ecosystems.
Respiration releases energy and carbon dioxide; energy is not produced as a substance.
Plants respire all the time, not only at night.
Do not repeat only the labels from a carbon or water cycle diagram; link them to processes such as photosynthesis, respiration, evaporation or precipitation.