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Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
The lipid bilayer is made of phospholipids. They are arranged in a double layer because one of their ends is attracted to water while the other is repelled by water.
Aspirin is the most widely used drug in the world. It has even been recognized as such by the Guinness Book of World Records.
About one in five American adults and teenagers have had a genital herpes infection—and most of them don't know it. People with genital herpes have at least twice the risk of becoming infected with HIV if exposed to it than those people who do not have genital herpes.