1911-1997

American biochemist who won the 1961 Nobel Prize for chemistry for elucidating the process of photosynthesis in plants. Calvin began work on photosynthesis in the 1940s, studying algae to determine the biochemical interactions by which water and carbon dioxide are transformed into carbohydrates and oxygen. By using the radioactive isotope carbon-14, he was able to identify the reactions involved in the different stages of photosynthesis.