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秋天到了,树叶黄了,一群大雁往南飞。很多绿色的叶子不约而同地在秋天换上了新衣,黄的,红的,灰的。为什么秋天很多树叶会变黄呢?叶子变黄的原因是它含有叶绿素和叶黄素。在春天和夏天,太阳光照长,气温高,水汽充足,新生叶子叶绿素的含量大约是叶黄素等其他色素的8倍,其他色素的颜色被绿色掩盖,就看不出了,所以叶子就呈现叶绿素的颜色—绿色。但是到了秋季,白天缩短夜晚延长,太阳光照相对不足,气温开始降低,叶子的吸水能力也减弱了,
Autumn is coming, yellow leaves, a group of geese fly south. Many green leaves invariably put on the new clothes in the fall, yellow, red, gray. Why do many leaves turn yellow in autumn? The reason the leaves turn yellow is that it contains chlorophyll and lutein. In spring and summer, the sun is long, the temperature is high and the water vapor is plentiful. The content of chlorophyll in newborn leaves is about 8 times that of other pigments such as lutein. The color of other pigments is covered by green and can not be seen, so the leaves appear Chlorophyll color - green. But in the fall, the night shortened to shorten the daylight, the relative lack of sunlight, the temperature began to decline, the water absorption capacity of the leaves also weakened,