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Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
The human body produces and destroys 15 million blood cells every second.
A good example of polar molecules can be understood when trying to make a cake. If water and oil are required, they will not mix together. If you put them into a measuring cup, the oil will rise to the top while the water remains on the bottom.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
In the ancient and medieval periods, dysentery killed about ? of all babies before they reach 12 months of age. The disease was transferred through contaminated drinking water, because there was no way to adequately dispose of sewage, which contaminated the water.