Plants are autotrophs, which means they produce their own food. They use the process of photosynthesis to transform water, sunlight, and carbon dioxide into oxygen, and simple sugars that the plant uses as fuel. These primary producers form the base of an ecosystem and fuel the next trophic levels.
This the respiratory system!
The major organ of the respiratory system is the lungs, and in the lungs the air gets divided among smaller and smaller tubes at the end of which the oxygen enters and carbon dioxide leaves the blood!
C)set maximum contaminant levels for pollutants in drinking water
