To breathe, they use the <span>the carbon dioxide. Carbon dioxide is the main element which help the organisms to breathe.</span>
Answer:
Nothing
Explanation:
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They produce oxygen they are used as shelter, they are used for blocking the shade, they sustain other animals that sustain the planet and us.
Some blood cells responsible for the transportation of oxygen and other are there for rebuilding of tissues. Fights things the body doesn't recognize
