Photosynthesis Is a Process in Plants, Algae,

Photosynthesis is a process in plants, algae, and some prokaryotes, that coverts solar insulation into chemical energy stored in glucose or other organic compounds. Photosynthesis occurs in slightly different ways in higher plants relative to photosynthetic bacteria. Photosynthesis is an important process because it harnesses the sun's energy into utilizable forms of energy on earth. Most biological organisms such as animals and fungi are unable to directly use light energy to power biological processes such as active transport, cell division and muscle movement. ATP is used to power these processes. Photosynthesis converts light energy into chemical energy in the form of glucose and then the process of cellular respiration converts energy in glucose to energy in the form of ATP which is ultimately used to power biological processes. The energy produced by photosynthesis forms the foundation of virtually all terrestrial and aquatic food chains. As a result, photosynthesis is the crucial source of carbon in the organic molecules found in most organisms. The high oxygen concentration in the atmosphere is derived directly from the light reactions of photosynthesis. Prior to the evolution of photosynthesis on earth, the atmosphere was absent of any oxygen

The rate of photosynthesis is determined by environmental factors. Factors affecting photosynthetic rates include light intensity, water availability, soil nutrient content, concentration of carbon dioxide and temperature. When water availability is reduced, photosynthesis is mainly limited by a decrease in the diffusion of CO2 into the leaf through the stomata. Stomata typically close when atmospheric humidity and soil moisture availability decline. Under these conditions, elevated light conditions can cause thylakoid membranes to become injured in a process known as photoinhibition. As a result photosynthesis is limited by photoinhibition. A similar decline of photosynthetic effectiveness is observed when water availability is inhibited by overgrazing induced root zone reduction combined with inconsistent leaf destruction.

As internal leaf CO2 concentrations decline due to stomatal closure, the enzyme Rubisco tends to fix more oxygen and frees CO2 in a process known as photorespiration. The net result is that photosynthesis becomes limited by the process of photorespiration. This process occurs mostly in C3 plants and is enhanced under hot dry conditions.