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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.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
Fewer than 10% of babies are born on their exact due dates, 50% are born within 1 week of the due date, and 90% are born within 2 weeks of the date.
Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.
In the United States, an estimated 50 million unnecessary antibiotics are prescribed for viral respiratory infections.
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