Answer:
Step-by-step explanation:
Cells start undergoing anaerobic respiration when energy requirement is high and there is not sufficient availability of oxygen to produce required energy .
For example , when we we run fast , energy requirement by muscle cell is high but available oxygen level is not sufficient so cells start anaerobic respiration which produces lactic acid and this product creates tire-ness.
For normal respiration , oxygen is required . If there is lack of oxygen , aerobic respiration is not possible .
In yeast cells , alcohol is produced by anaerobic respiration. Alcohol is not harmful . In muscle cells , lactic acid is produced which is harmful .