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What is a desert?
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Why are deserts growing?
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What is the coldest desert?
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What is "living stones"?
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What is a nitrogen cycle?
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How do plants participate in the water cycle?
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What happens to the fallen leaves?
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What plants improve the soil?
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How do plants help fight erosion?
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For whom is a tree a home?
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How are plants used for sewage treatment?
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How do plants fertilize the soil?
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How do plants "populate" the earth?
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How do the woods clean the air?
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Where does the seeds develop?
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How is the seed spread?
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Why do flowers dissolve in spring or summer?
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Which plants have the least seeds?
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How much seed can one plant give?
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What flowers are pollinated by beasts?
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Why is there a lot of poisonous seeds?
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How do pollen produce flowers?
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What happens in the flower after pollination?
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How do flowers pollinate?
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Can plants be multiplied without seeds?
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