✳ Môi trường đới lạnh
- Vị trí : Nằm khoảng từ hai vòng cực đến hai cực
- Đặc điểm khí hậu : Vô cùng khắc nghiệt ; nhiệt độ và lượng mưa rất thấp , chủ yếu dưới dạng tuyết dơi . Mùa đông rất dài , nhiệt độ dưới -10oC . Mùa hạ kéo dài 2-3 tháng , nhiệt độ không quá 10oC . Đất đóng băng quanh năm
- Sinh vật : Tự hạn chế thoát nước , đồng thời tăng cường dự trữ nước và chất dinh dưỡng trong cơ thể .
✳ Môi trường hoang mạc .
- Vị trí : Nằm dọc 2 bên cí tuyến Bắc , Nam và năm sâu trong nội địa hoặc nơi có dòng biền lạnh đi qua .
- Đặc điểm khí hậu : Rất khô hạn , khắc nghiệt . Lượng mưa trong năm rất thấp nhưng lượng mưa bốc hơi nước rất lớn . Sự chênh lệch nhiệt độ giữa ngày và đêm cũng rất lớn .
- Sinh vật : + Chúng thích nghi nhờ có bộ lông dày , lông không thấm nước hoặc lớp mỡ dày...
+ Sống theo bầy đông , di cư hoặc ngủ đông
giúp minh 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