Photosynthesis, Light Reactions And
Life requires a continuous input of energy. On Earth, the main source of energy is sunlight, which is transformed by photosynthesis into a form of chemical energy that can be used by photosynthetic and nonphotosynthetic organisms alike. Photosynthesis is the molecular process by which plants, algae, and certain bacteria use light energy to build molecules of sugar from carbon dioxide (CO2) and water (H2 O). The sugar molecules produced by photosynthetic organisms provide the energy as well as chemical building blocks needed for their growth and reproduction. In plants and algae the photosynthetic process removes CO2 from the atmosphere while releasing molecular oxygen (O2) as a by-product. Some photosynthetic bacteria function like plants and algae, giving off O2; other types of photosynthetic bacteria, however, use light energy to create organic compounds without producing O2. The type of photosynthesis that releases O2 emerged early in Earth's history, more than three billion years ago, and is the source of the O2 in our atmosphere. Thus photosynthetic organisms not only provide the food we eat, but also the air we breathe. In addition, ancient photosynthesis produced the building blocks for the oil, coal, and natural gas that we currently depend on for our survival.
This page contains 201 words.
Photosynthesis, Light Reactions And article
Read the rest of this article.
This article contains 2,792 words
(approx. 9 pages at 300 words per page).
Order our Light-dependent reaction Article
