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There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
People who have myopia, or nearsightedness, are not able to see objects at a distance but only up close. It occurs when the cornea is either curved too steeply, the eye is too long, or both. This condition is progressive and worsens with time. More than 100 million people in the United States are nearsighted, but only 20% of those are born with the condition. Diet, eye exercise, drug therapy, and corrective lenses can all help manage nearsightedness.
People with high total cholesterol have about two times the risk for heart disease as people with ideal levels.
In 2006, a generic antinausea drug named ondansetron was approved. It is used to stop nausea and vomiting associated with surgery, chemotherapy, and radiation therapy.
For about 100 years, scientists thought that peptic ulcers were caused by stress, spicy food, and alcohol. Later, researchers added stomach acid to the list of causes and began treating ulcers with antacids. Now it is known that peptic ulcers are predominantly caused by Helicobacter pylori, a spiral-shaped bacterium that normally exist in the stomach.
![Muskox populations remain in the Arctic all year, though they migrate to higher elevations in the wi](https://biology-forums.com/gallery/47/medium_33_22_09_11_9_37_27_1803362.jpeg)
![When young infants hold objects for a long period of time they eventually become habituated to them.](https://biology-forums.com/gallery/47/medium_637842_18_01_17_6_02_54_245021528.png)