- Photosynthesis occurs within plants' leaves.Jupiterimages/Photos.com/Getty Images
Photosynthesis describes the process of taking light energy and converting it into other substances. Through photosynthesis, plants create sugars and other organic compounds. For photosynthesis to occur, plants require light, carbon dioxide and water. Oxygen and carbohydrates are created and given off as a result of photosynthesis. After the initial light absorption, photosynthesis then breaks down into two parts.
- Nearly all plants require at least a minimal amount of light energy to grow, which usually comes from the sun. Light hits the plant leaves and penetrates into the cells. Leaves feature parts known as chloroplasts within the mesophyll, or cellular layer between the upper and lower epidermis of a leaf. Chloroplasts contain a substance called chlorophyll, which gives plants its green color. According to the University of Cincinnati Clermont College biology department, chloroplasts absorb red and blue light but not green light. Once the light from the sun or another light source has been absorbed, the process of photosynthesis begins within the chloroplasts.
- This first part of photosynthesis is referred to as a light-dependent reaction because to carry out these steps, the plants must have light. Light is what triggers the plant into the process of photosynthesis. Once the light has been absorbed, chlorophyll transforms the light energy into chemical energy, creating a substance called adenosine triphosphate, or ATP. Cells use ATP to store energy.
- Once the ATP is created, plants begin what is known as the light-independent reaction. According to Estrella Mountain Community College's online biology book, plants pull carbon dioxide from either the air or water, then combine it with water to form carbohydrates. In addition to making carbohydrates, plants take the ATP formed and use it, along with carbon dioxide, to create glucose, or sugar. The process of taking ATP and turning it into sugar is known as the Calvin Cycle. Oxygen is made during these reactions as a byproduct, then released into the air for use by animals.