When Does a Tree Have to Be Pruned?
When Does a Tree Have to Be Pruned? Trees have to be pruned to protect their health, improve their appearance or remove danger to people or property. Sometimes it is...
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Where Do Lichens Grow?
Where Do Lichens Grow? Lichens are found throughout the world, often occupying areas where no other plant can become established. They are found in the Alpine and...
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What Are Fossils?
What Are Fossils? Fossils are the remains, molds, traces or impressions of prehistoric animals and plants found in the ground. The word comes from the Latin fodere,...
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Why Do Cats Purr?
Why Do Cats Purr? Most people think that cats purr to show pleasure or contentment. Purring is a kind of low continuous rattling hum, but it has nothing to do with a...
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Why Do Birds Have Hollow Bones?
Why Do Birds Have Hollow Bones? Birds fly so well because they have developed skeletons which are especially light and strong. Most of their bones are hollow, with the...
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Where Would You Find a Red Giant?
Where Would You Find a Red Giant? You would find a Red Giant on the Sierra Nevada Mountains of California in North America. It is a huge redwood tree, called a giant...
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When Was Rubber Discovered?
When Was Rubber Discovered? Although the remarkable properties of the rubber tree were known to the Aztecs and other South American Indians, for perhaps a thousand...
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What Is Photosynthesis?
What Is Photosynthesis? Photosynthesis is the process by which green plants make food for themselves-and, indirectly, for all animals, including human beings. In...
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Why Are Vampire Bats Dangerous?
Why Are Vampire Bats Dangerous? Vampire bats are dangerous because they carry rabies and other diseases and infect their victims as they suck the blood which is their...
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When Does Pollution Kill a River?
When Does Pollution Kill a River? A river will die when pollution reaches such a level that all the available oxygen is absorbed. This can happen if the oxygen is used...
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