Answer:
It is useful during exercise. When the body doesn't get enough oxygen during exercise, it relies on anaerobic respiration for an energy supply. Instead of carbon dioxide and water, however, anaerobic respiration produces lactic acid. Also, anaerobic respiration releases less energy than aerobic respiration but it does this more quickly.
Hope this helped.
- profparis
I don’t know 22 but I think 21 is B
