Definition of tae kwon do for English Language Learners. : a style of fighting that originated in Korea and that uses kicks and punches but no weapons. Britannica.com: Encyclopedia article about tae kwon do.
It is also used in the baking process as a leavening agent; yeast releasing gas into their environment results in the spongy-like texture of breads and cakes. Because of its role in fermentation, humans have known about and used Saccharomyces cerevisiae for a long time.
Depending upon the organism, fermentation can occur in the presence (aerobic) and/or in the absence (anaerobic) of oxygen. Fermentation pathways produce byproducts such as carbon dioxide, ethanol (alcohol), or organic acids (lactic acid or acetic acid, for example).lcohol fermentation is often used in bacteria in anaerobic conditions as well as in yeast. Interestingly, the carbon dioxide that is released in alcohol fermentation generated by a baker's yeast is what allows the bread to rise!