A problem with either stomach acid or intrinsic factor can lead to a vitamin B12 deficiency. Oral vitamin B12 supplements contain a form of vitamin B12 that is easy to absorb without stomach acid, but these pills may not treat all causes of vitamin B12 deficiency.People who have undergone gastric bypass surgery, for example, can develop a deficiency in the intrinsic factor. vitamin B12 deficiency has a wide range of symptoms. Someone with low vitamin B12 may lose their appetite, lose weight or feel tired and weak. Depression, poor memory and trouble thinking can all be symptoms of a vitamin B12 deficiency.
Exothermic reactions: Heat is released. 1) Combustion: The burning of carbon-containing compounds uses oxygen, from air, and produces carbon dioxide, water, and lots of heat. 2) Rain: Condensation of water vapor into rain releasing energy in the form of heat is an example of an exothermic process.
More generally, the terms exergonic and endergonic relate to the free energy change in any process, not just chemical reactions. An example of an exergonic reaction is cellular respiration. By contrast, the terms exothermic and endothermic relate to the overall exchange of heat during a process.