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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.
Cyanide works by making the human body unable to use oxygen.
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.
After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.
Approximately 500,000 babies are born each year in the United States to teenage mothers.