Photosynthesis happens in chloroplast, which contains chlorophyll.
Its the process in which plants make their own food by intaking six molecules of carbon dioxide, water, and sunlight in order to make sugar and release oxygen. The process of respiration starts when a human or an animal breaths in oxygen the plants release.
As the oxygen and glucose move throughout our body through our bloodstream. In small cellular cells called mitochondria, the glucose and oxygen through the respiration reaction. When the reaction is over carbon dioxide, water, and ATP is left. The CO2 is released int your lungs, and you breath it out.
ATP means adenosine triphosphate. It's used to power cells that need work. It's energy that you store.
Plants use respiration through their roots, stem, and leaves. The stoma in the leaves are used to exchange gases, so it takes in and out both oxygen and carbon dioxide. The roots also collect oxygen from the little bits of air that are down in the cracks of the soil.
Plants use the oxygen to breakdown the glucose to make carbon dioxide and water.