Regeneration reproduction It grow back regrowth
Normally, oxygen from the blood cells supply your muscles with the energy it needs to carry out certain actions. However, when there isn't enough oxygen to support the muscles, it produces lactic acid, or fermentation, to make up for the oxygen. (That's why you get that burn-y feeling whenever you exercise!)
Answer:
Scientists estimate that at least 99.9 percent of all species of plants and animals that ever lived are now extinct.
Explanation:
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