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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.
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.
Approximately 500,000 babies are born each year in the United States to teenage mothers.
The average older adult in the United States takes five prescription drugs per day. Half of these drugs contain a sedative. Alcohol should therefore be avoided by most senior citizens because of the dangerous interactions between alcohol and sedatives.
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.