How would the amount of carbon dioxide in the atmosphere change if there were no plants?
1. No change
2. It would increase
3. It would decrease

it would increase

Explanation:

plants take in carbon dioxide and give oxygen

1) It would increase

This would because plants make photosynthesis wich coverst carbon dioxide into oxygen. Whithout plants, there would be no oxygen; no clean air for humans to breath.

Explanation:

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what do the different brain waves do?

explanation:

brainwaves are produced by synchronised electrical pulses from masses of neurons communicating with each other. brainwaves are detected using sensors placed on the scalp. brainwave speed is measured in hertz (cycles per second) and they are divided into bands delineating slow, moderate, and fast waves.