The cells of green plants contain the pigment chlorophyll in organelles called chloroplasts. Chloroplasts capture the Sun’s energy and store it―through photosynthesis―as chemical energy. The reactants for photosynthesis are water, H2O(l), and carbon dioxide, CO2(g). The products are carbohydrates, C6H12O6(aq), (compounds that store chemical energy) and oxygen, O2(g), which is released into the atmosphere.
Cells of living organisms use the oxygen and carbohydrates thus produced to release energy in a process called cellular respiration, in which carbon dioxide is released.
Both animal and plant cells carry out cellular respiration to generate the energy needed for cellular processes.