You are running a thousand five hundred meter rates. Breathing deeply to get the oxygen so that you can respire and keep up the energy supply to your muscles. Your muscles keep wanting more and more energy but your lungs can't keep up. Do you have to quit the race? No. In the respiration video we discovered the difference between aerobic and anaerobic respiration and then looked at aerobic respiration in more detail. Sometimes animals and plants can't get enough oxygen to respire aerobically such as during intense exercise but they still need to respire to survive. After all everything relies on respiration for energy. Luckily there is a backup plan and aerobic respiration. In this video we are going to have a look at anaerobic respiration in both animals and plants. Starting with animals, a cheetah sprinting to catch some prey cannot take in enough air and blood around the body force enough for aerobic respiration. The heart and lungs can't keep up so anaerobic respiration is carried out instead. Here is the generalized equation for anaerobic respiration. See how it differs from aerobic respiration. There is no oxygen involved in anaerobic respiration. It is much less efficient than aerobic respiration and much less energy is released. This is because the glucose is only partially broken down. Another problem is that lactic acid is produced. This is actually a poisonous chemical that if it builds up in the body the muscle stops working and you get a muscle cramp. You can only get rid of lactic acid by taking in oxygen again and thus replacing the oxygen tape. Oxygen is needed to break down lactic acid, turning it into carbon oxide and water. Do you know how you breathe deeply after intense exercise? This is your body replacing the bolt of oxygen tape. So that is how anaerobic respiration works in animals. What about in plants? The oxygen supply can run out for plants too, such as in waterlogged soils. The steam forces plants to have to carry out anaerobic respiration as they too need to respire constantly. Here is a generalized anaerobic respiration equation for plants. Notice how instead of lactic acid being produced, ethanol and carbon dioxide is made instead. In heast this process is called fermentation and it is used to break bread and brew alcohol. Next and all is the alcohol found in beer and wine for example. And in bread making it is a carbon dioxide that is useful. The bubbles in carbon dioxide help the bread rise by expanding the dough. So you should now know that when our heart and lungs cannot keep up with the oxygen demand or plans to not have access to sufficient oxygen, we have a bee plant and anaerobic respiration. This is when the glucose is broken down directly, but it produces much less energy than aerobic respiration, which is why it is the second choice. And in animals it produces lactic acid as a byproduct which causes muscle cramps. And so we end up with an oxygen tape which needs repaying of the exercise as stopped.