Cells are the basic units of life and their processes are vital to the functioning of all organism. The reactions of photosynthesis and cellular respiration are complimentary and are also the most important pathways on the Earth. Photosynthesis is a process that converts carbon dioxide into organic compounds in presence of sunlight. Cellular respiration is the set of metabolic reactions that take in cells of living organisms that convert nutrients like sugar into energy , which is known as ATP (adenosine triphosphate), and waste products. The two processes are closely related and likewise, they share many similarities and differences
Processes in a Nutshell
The main difference between photosynthesis and cellular respiration is that photosynthesis takes place in the chloroplast and cellular respiration takes place in the mitchondrion. Plants contain mitochondria and chloroplasts so both they may undergo both processes. However, animals and other heterotrophs undergo cellular respiration, but not photosynthesis. In a nutshell, the purpose of these processes is to convert free energy into ATP.
Discovery of Photosynthesis
The beginning of the discovery of photosynthesis began in the mid-17th century when J.B. Van Helmont carefully measured the mass of the soil used by a plant and the mass of the plant as it grew. After this noticed that the soil mass changed very little. He then hypothesized that the mass of the growing plant must come from the water. His hypothesis was partially accurate as much of the gained mass also comes from carbon dioxide as well as water. After this in 1771, Joeseph Priestley, an English scientist, discovered that, when he lit a candle in a closed container it would burn out. However, once he placed a mint plant in the container the candle could burn once again. This discovery supported that plants release some type of gas into the air that supports combustion. In 1796, Jan Ingenhousz, a Dutch medical doctor, repeated Priestley's experiments and confirmed his findings. He also eluded that the gas released was oxygen. Around this time, Jean Senebier, a Swiss pastor, botanist, and naturalist, demonstrated that green plants consume carbon dioxide and release oxygen under the influence of light. Soon afterward, Nicolas-Théodore de Saussure showed that the increase in mass of the plant as it grows could not be due only to uptake of carbon dioxide, but also to the incorporation of water. Thus, the basic reaction by which photosynthesis is used to produce food (such as glucose) was outlined. In the early 1930's, Cornelis Van Niel made important discoveries that help explain the chemistry of photosynthesis. By studying purple sulfur bacteria and green bacteria he was the first scientist to demonstrate that photosynthesis is a light-dependent redox reaction, in which hydrogen reduces carbon dioxide. Robert Emerson conducted experiments that helped him discover that there were two photosytems, one...