This dog uses cellular respiration to breath in oxygen, & breath out Carbon Dioxide.
That tree uses Photosynthesis to release oxygen out into the atmosphere so that animals can breath. They also use Photosynthesis to make their own food.(and animals eat plants or things that eat plants to get energy) Pretty cool, huh?
In cellular respiration the first step happens in a cell's cytoplasm. The glucose molecules are broken down into smaller molecules. This step uses no oxygen and only releases a little bit of energy.
During the second stage of cellular respiration in the cell's mitochondria the small glucose molecules are broken down into even smaller molecules using oxygen. Lots of energy is released during this stage.
In the first stage of photosynthesis chloroplasts capture the energy from the sunlight. During the second stage of photosynthesis the cells of the plants use the energy to make sugar but it needs water and carbon dioxide for this process. Water and carbon dioxide go through a group of chemical reactions which are powered by the energy in stage 1. The products are oxygen and glucose. The chemical reactions happen in the chloroplasts.