Answer:
Plants perform both photosynthesis and cell respiration and cause a net decrease of carbon in the atmosphere.
Explanation:
Plants are living organisms capable of performing a process called photosynthesis, which they use to synthesize their food (sugar). They use carbon in form of carbon dioxide, which they absorb from the atmosphere via their stomata.
However, plants like every other living organism, also perform cellular respiration. Cellular respiration releases carbon in form of carbon dioxide into the atmosphere. Plants use more carbon dioxide than they release into the atmosphere, hence, they contribute to global carbon cycle perform both photosynthesis and cell respiration and cause a net decrease of carbon in the atmosphere.