Photosynthesis is the process that produces organic molecules from simple inorganic molecules from the sun’s energy. This process is used by plants to create their own food. The word photosynthesis comes from the Greek words photo, meaning light, and synthesis, meaning putting together.
The first step of photosynthesis is when light hits the pigment in a plant cell’s chloroplast and splits water into hydrogen and oxygen atoms. Next, CO2 enters the plant through tiny holes called stomata on the underside of leaves. The carbon dioxide molecule then joins with a water molecule inside the chloroplast to form a new compound called 3-phosphoglycerate (3-PGA). This 3-PGA molecule then goes through a series of reactions that eventually produce glucose, a type of sugar that plants use for food.
Oxygen gas is also produced during photosynthesis as a waste product. Plants release this oxygen gas out of their stomata into the air where we breathe it in. We need this oxygen gas to live! Photosynthesis therefore not only provides food for plants, but also provides us with the oxygen we need to breathe.
There are two types of photosynthesis: aerobic and anaerobic. Aerobic means “with air” while anaerobic means “without air”. In aerobic photosynthesis, which takes place in most green leaves, water vapor is released as a waste product along with oxygen gas. Anaerobic photosynthesis does not produce oxygen gas as a waste product; instead it produces methane or other compounds such as sulfur dioxide or nitrous oxide gases depending on what type of bacteria is performing it . Methane production during anaerobic photosynthesis occurs in wetlands and is one reason why these areas are sometimes called “swampy.”