The human body produces about twenty-five million new cells every second.
Why it is true
This continuous process of cell division is essential for replacing dead cells, healing wounds, and the growth of the organism throughout life.
Source: Cytology
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.