Examples_6th_Biology

Examples_6th_Biology - Biology Examples The Cactus in the...

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Unformatted text preview: Biology Examples The Cactus in the Desert Deserts are harsh places: dry, hot, and barren, so the cactus is one of the few plants able to survive the difficult environment. The cactus manages to survive in the desert for several reasons: first, most cacti are covered in spines, which protect them from animals looking for food, and give them shade against the bright sun. Second, cacti are covered in a waxy coat called a glaucus bloom, which keeps moisture in, never allowing the plant to dry out. Third, during brief rainstorms, cacti collect extra water inside them like barrels, then gradually use that water through the dry months ahead. Fourth, a cactus usually spreads its roots out to the side to catch rain water from all around it. For these reasons, cacti are well adapted to living in the desert. But they did not start out that way. Cacti originally looked like plants that live in wetter climates, with large, soft leaves and deep, non-poisonous roots. As some climates slowly changed from rainy and cool to dry and hot, the soft, water-loving plants died out. Year by year, the only plants that could survive and produce seeds were the ones with slightly waxy surfaces, slightly smaller leaves, slightly wider roots. Over thousands of years, surfaces became waxier, leaves became so small they were more like spines, and roots became shallow the wide. This is the process of adaptation : a plant slowly changing to fit into its environment. The cactus is one of the few plants that can survive in the hot, dry desert environment. It manages to survive because it has adapted for life in the desert, by developing spines to protect it from animals, a waxy coat called a glaucus bloom that keeps moisture inside, and wide root systems to capture rainwater. But, millions of years ago, cacti looked like plants that live in wetter climates, with large, soft leaves and deep, non-poisonous roots. As some climates slowly changed from rainy and cool to dry and hot, the soft, water-loving plants died out. Year by year, the only plants that could survive and produce seeds were the ones with slightly waxy surfaces, slightly smaller leaves, slightly...
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Examples_6th_Biology - Biology Examples The Cactus in the...

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