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There are approximately 3 million unintended pregnancies in the United States each year.
A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
Amoebae are the simplest type of protozoans, and are characterized by a feeding and dividing trophozoite stage that moves by temporary extensions called pseudopodia or false feet.
The average human gut is home to perhaps 500 to 1,000 different species of bacteria.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
![Formation of additional eyes in Drosophila caused by the abnormal expression of a master control gen](https://biology-forums.com/gallery/47/medium_33_14_07_11_6_03_48.jpeg)
![Pneumonia. This common lung inflammation may be caused by bacteria, viruses, or fungi and is often d](https://biology-forums.com/gallery/47/medium_14755_11_11_12_7_23_11_100542416.jpeg)