So it's easier to understand how plants take in carbon-dioxide and how much carbon-dioxide is in the atmosphere
The Earth's atmosphere would have little or no oxygen. A by-product of photosynthesis is oxygen. Photosynthesis is the process by which green plants use energy from the sun to make their own food in the leaves. The process uses sun light, water and carbon dioxide to yield oxygen and simple sugars. The simple sugars are stored in form of starch for future use by the plants, while oxygen is either used for cellular respiration or released to the atmosphere. The process of photosynthesis adds oxygen to the atmosphere and uses carbon dioxide from the atmosphere.
Active transport, which occurs at the expense of energy.
Answer:
Oxygen is reduced, gaining electrons and hydrogen ions. -second choice
