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There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Approximately 500,000 babies are born each year in the United States to teenage mothers.
Barbituric acid, the base material of barbiturates, was first synthesized in 1863 by Adolph von Bayer. His company later went on to synthesize aspirin for the first time, and Bayer aspirin is still a popular brand today.
When Gabriel Fahrenheit invented the first mercury thermometer, he called "zero degrees" the lowest temperature he was able to attain with a mixture of ice and salt. For the upper point of his scale, he used 96°, which he measured as normal human body temperature (we know it to be 98.6° today because of more accurate thermometers).
When blood is deoxygenated and flowing back to the heart through the veins, it is dark reddish-blue in color. Blood in the arteries that is oxygenated and flowing out to the body is bright red. Whereas arterial blood comes out in spurts, venous blood flows.