They use them as food and habitats.
The various types of cells making up the structural composition of your body (skin cells, muscle cells, cells of your stomach lining, etc.) are all Epithelial cells. The only other class of cells in your body are Gametes (sperm and egg cells).
Answer:
If we did not have an atmosphere, we would fly out into space. We would also not be protected from harmful rays from the sun, and astroids. Human life would not live very long.
Explanation:
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