10.3a Anaerobic respiration in humans

• To understand the process of anaerobic respiration.

  Anaerobic respiration is a way cells produce energy without using oxygen. It happens when oxygen levels are low or absent. In this process, glucose is broken down into smaller molecules without oxygen, producing a small amount of energy and lactic acid (in animals) or alcohol and carbon dioxide (in yeast and some bacteria) as byproducts. It's not as efficient as aerobic respiration but helps cells survive when oxygen is scarce.
• Compare aerobic / anaerobic respiration

  Aerobic respiration requires oxygen and is more efficient, producing more energy from glucose. It occurs in the presence of oxygen and produces carbon dioxide and water as byproducts. Anaerobic respiration doesn't need oxygen, but it's less efficient, producing less energy. It occurs when oxygen is scarce and produces lactic acid (in animals) or alcohol and carbon dioxide (in yeast and some bacteria) as byproducts.
• Describe the effect of lactic acid and how its removed.

  Lactic acid can build up in muscles during intense exercise when oxygen is scarce. It causes muscle fatigue and a burning sensation. To remove lactic acid, the body needs oxygen. Once oxygen becomes available again, lactic acid is broken down into lactate and converted into carbon dioxide and water, which are removed from the body through breathing and circulation.
• Know where respiration takes place.

  Respiration takes place in the cells of living organisms, specifically within cellular structures called mitochondria. In aerobic respiration, the mitochondria are the primary site where the process occurs. Anaerobic respiration can also occur in the cytoplasm of cells when oxygen is scarce.
• State the equation for aerobic respiration.

  The equation for aerobic respiration is:

  Glucose + Oxygen → Carbon Dioxide + Water + Energy
• State the equation for anaerobic respiration

  The equation for anaerobic respiration in animals (like humans) is:

  Glucose → Lactic Acid + Energy

  And for anaerobic respiration in yeast and some bacteria:

  Glucose → Ethanol + Carbon Dioxide + Energy
• Know sport activities that rely on anaerobic respiration.


  Sprinting, weightlifting, and jumping (like high jump) are examples of sports relying on anaerobic respiration. These activities involve short bursts of intense effort, demanding quick energy from anaerobic metabolism.
• Know sport activities that rely on aerobic respiration .

  Sports that rely on aerobic respiration include long-distance running, cycling, swimming, and cross-country skiing. These activities involve sustained, moderate-intensity efforts that require a continuous oxygen supply for energy production.
• Know the effects of lactic acid.

  Lactic acid can cause muscle fatigue, soreness, and a burning sensation during intense exercise.
• Know how lactic acid is removed after exercise.

  Lactic acid is removed after exercise by being converted into lactate and broken down into carbon dioxide and water, which are eliminated from the body through breathing and circulation.