Answer:
<em><u>carbon dioxide</u></em>
Explanation:
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Everything in Earth's system can be placed into one of four major subsystems: land, water, living things, or air. These four subsystems are called “spheres.” Specifically, they are the lithosphere (land), hydrosphere (water), biosphere (living things), and atmosphere (air)...
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Answer:
the total mass of organisms in a given area or volume.
Explanation: