During Trip 3, you learned about "regular", aerobic cellular respiration. This energy-producing process requires oxygen and the by-product is CO2. When oxygen is not available, plants and some fungi produce ethanol instead of CO2 in a process called anaerobic respiration. Other fungi and animals produce lactic acid instead of CO2 when deprived of oxygen.
To experience the effects of an animal going through anaerobic respiration in its muscle cells, all you need to do is run a quarter-mile faster than you think you can. (Do not do this if you have a cardiovascular condition.) Even though you will be breathing in oxygen the whole time, your lungs and cardiovascular system will not be able to meet the demand for oxygen from your muscle cells. Without enough oxygen, your muscles are forced into the less-efficient-for-producing-energy process called anaerobic respiration. Without enough energy, you will not be able to keep up the same pace as you might if you only ran 100 meters. Also, many people report a distinctive taste in their mouth after this activity, which may be the lactic acid itself coming through your saliva.
The yeasts Saccharomyces cerevisiae and Saccharomyces pastorianus are two of the fungi that produce ethanol when deprived of oxygen. Combine them with grain, hops and water, then take away their access to oxygen in a container and you get beer. The Oregon Brewers Festival is one of the best places to sample the results of these fungi being suffocated.
Here at Experiencing Life, we recommend doing the beer festival after the quarter-mile run, not before!