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In the ancient and medieval periods, dysentery killed about ? of all babies before they reach 12 months of age. The disease was transferred through contaminated drinking water, because there was no way to adequately dispose of sewage, which contaminated the water.
This year, an estimated 1.4 million Americans will have a new or recurrent heart attack.
The lipid bilayer is made of phospholipids. They are arranged in a double layer because one of their ends is attracted to water while the other is repelled by water.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).
![Mutualisms, such as those that occur among plants and pollinators, generally involve large numbers o](https://biology-forums.com/gallery/47/medium_33_17_02_12_5_38_22_1981973.jpeg)
![Peptic ulcer. A peptic ulcer may occur in the stomach (gastric ulcer), as shown here, or in the duod](https://biology-forums.com/gallery/47/medium_14755_26_10_12_5_23_53_96882468.jpeg)