A conversion disorder is a relatively uncommon mental disorder in which a person has physical symptoms that no medical condition, physical examination or testing can explain. The person is not faking.. The symptoms do not appear to be under the person's conscious control and they can cause significant distress.
The most important chemical reaction of all is photosynthesis. At first I thought that the most important reaction was respiration, the set of reactions in our cells that keeps us alive by combining glucose with oxygen and provides the energy that keeps us alive. Then I realized that we would not be alive without the oxygen in the first place.
The nucleus is particularly important among eukaryotic organelles because it is the location of a cell's DNA. Two other critical organelles are mitochondria and chloroplasts, which play important roles in energy conversion and are thought to have their evolutionary origins as simple single-celled organisms.