1. Photosynthesis increases oxygen levels, as oxygen is one of the remainders from photosynthesis. Remember, for photosynthesis to happen plants taken carbon dioxide and release oxygen.
2. Cellular respiration will decrease oxygen levels. For cellular respiration to occur animals take in oxygen and release carbon dioxide.
3. If there is a higher light intensity then there will be higher levels of oxygen production. Plants need energy in the form of sunlight in order to photosynthesize, and the more photosynthesis that is done the more oxygen that is produced.
