Como as plantas ajudam a diminuir a quantidade de gas carbonico no ar

By consuming carbon dioxide and releasing oxygen

Explanation:

The plants use the process of photosynthesis in order to make their own food, sugars. One of the things that the plants use for this process is the carbon dioxide. They take in this gas from the atmosphere, and in lesser amounts from the soil, and once they have used the carbon, they release oxygen as a waste product. The plants are a natural storage for the carbon, as they retain big portion of the carbon they use, thus removing it from the atmosphere. On the other hand, with the releasing of oxygen as a waste product, they are increasing the amount of oxygen in the atmosphere.