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Normal urine is sterile. It contains fluids, salts, and waste products. It is free of bacteria, viruses, and fungi.
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.
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.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
During pregnancy, a woman is more likely to experience bleeding gums and nosebleeds caused by hormonal changes that increase blood flow to the mouth and nose.