Photosynthesis is also important in reducing the amount of CO 2 in the atmosphere. Higher CO 2 concentrations in the atmosphere are one of the causes of the greenhouse effect. Pinus flexilis , Limber Pine. A shade intolerant species. James L. Reveal, USDA, Plants National Database .
Photosynthesis is important in other ways too.
Plants, and related organisms which include algae and blue green bacteria, are the primary producers on our planet. They are the only organisms that can take the inorganic ingredients of water and CO 2 and make them into organic molecules that can be used as food by other organisms. Specifically, photosynthesis results in the synthesis of sugars. From these raw materials, and nutrients, such as nitrogen and phosphorus, plants are then able to make all the other molecules required to survive. And it is a good thing plants are able to do this, as all animals, including humans, ultimately rely on plants for food.