What is Photosynthesis?

Photosynthesis is the process plants and certain bacteria uses solar energy to change into chemical energy and then produce carbohydrates (sugars) and oxygen. The solar energy comes from the light from the sun. Inside plants there are organelles called chloroplasts, which is the main site where photosynthesis occurs. The molecule that absorbs the light is called chlorophyll. In the organelles, the solar energy powers the conversion of Carbon Dioxide (what we exhale) and water to glucose (sugar) and Oxygen (what we need to breathe).


The Light and Dark Reactions

The process of photosynthesis does not happen at once. It is split into two types of reactions. The first reactions occurs during the day. They are light dependent and therefore we call them the "light reactions". The other half of the job is carried out during the day, or even at night. They are light independent, called the "dark reactions" or also known as the Calvin Cycle.

The job for plants during the day is to store the solar energy into a chemical called ATP. The ATP is then used to power the Calvin Cycle where the production of glucose (a carbohydrate) happens and oxygen forms as a waste product! But oxygen as a waste product? Don't people and animals live off of oxygen? That's exactly correct and that is why plants are so important to our ecosystem.

History For Kids
