I believe that the most common antibody switch is from IgM to IgG.
Class switching occurs by a mechanism called the class switch recombination binding. It is a biological mechanism that allows the class of antibody produced by an activated B cell to change during a process known as isotype or class switching. The mechanism changes a B cell's production of antibodies from one form to another, such as from the isotype IgM to the isotype IgG.
Lack of predators.
An abundance of Food.
<span>In the presence of oxygen, one glucose molecule has the energy to make up to 38 ATP. The ATP production is determined by the following steps, (-2 ATP) glycolysis preparatory phase, (7-9 ATP) glycolysis pay-off phase, (5 ATP) oxidative decarboxylation of pyruvate and (20 ATP) Krebs cycle. One glucose which has 38 ATP hence was the summation of all the process mentioned that took place. All these process take place under the cellular function of cellular respiration.<span>
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Nowadays, that theory is rejected. Friedrich Wohler was able to synthesize urea from cyanic acid and ammonium, both being inorganic matter. <---This disproves the theory of vitalism.