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Did you know?

Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.

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On average, someone in the United States has a stroke about every 40 seconds. This is about 795,000 people per year.

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The most dangerous mercury compound, dimethyl mercury, is so toxic that even a few microliters spilled on the skin can cause death. Mercury has been shown to accumulate in higher amounts in the following types of fish than other types: swordfish, shark, mackerel, tilefish, crab, and tuna.

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Adult head lice are gray, about ? inch long, and often have a tiny dot on their backs. A female can lay between 50 and 150 eggs within the several weeks that she is alive. They feed on human blood.

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More than 50% of American adults have oral herpes, which is commonly known as "cold sores" or "fever blisters." The herpes virus can be active on the skin surface without showing any signs or causing any symptoms.

Some of the bacteria that can fix atmospheric nitrogen, converting it into a form usable by plants. Some of the bacteria that can fix atmospheric nitrogen, converting it into a form usable by plants.
Stratigraphic section of the Fayum shows the relative age of early anthropoid fossils. Stratigraphic section of the Fayum shows the relative age of early anthropoid fossils.
This chart shows the various lines of responsibility and how they differ in presidential and parliam This chart shows the various lines of responsibility and how they differ in presidential and parliam
Figure 7.1 shows the rapid decline in the trust of Americans in government since the 1960s. This de Figure 7.1 shows the rapid decline in the trust of Americans in government since the 1960s. This de
Nomogram chart. This example shows a line drawn from a child’s height of 100 cm to his weight, 35 ... Nomogram chart. This example shows a line drawn from a child’s height of 100 cm to his weight, 35 ...
An angiogram that illustrates narrowing of the carotid artery (see arrow), the main pathway of blood ... An angiogram that illustrates narrowing of the carotid artery (see arrow), the main pathway of blood ...
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