The fifth grade of primary school needs a science composition.
"Why do maple leaves turn red in autumn?" As we all know, maple leaves turn red in autumn, like a burning flame, which is very beautiful. But do you know why maple leaves turn red in autumn? Second, the answer to the question turns out that after autumn and winter, deciduous trees will undergo some chemical changes in their bodies, so that useful substances or some tissues contained in the original leaves can be recycled and stored in stems or roots, which can be reused next spring. Chloroplast and chlorophyll are one of the objects that are decomposed and recycled. Therefore, when the chlorophyll in the leaves is gone, the colors of other pigments are highlighted, such as the red of anthocyanin and the yellow of carotene, and then the leaves are adjusted for the winter! Besides chlorophyll, there are many other pigments in plant leaves, such as yellow lutein, carotene and red anthocyanin. (Anthocyanin is red in acidic solution and purple in alkaline solution), but because of its high chlorophyll content, it covers other colors and makes the leaves green. In autumn, due to the temperature drop, chlorophyll gradually decomposes, and the colors of other pigments are exposed. In addition, the sugar stored in maple leaves will be decomposed into anthocyanins, making the leaves brighter. Third, summary This is the reason why maple leaves turn red. In life, there are many such examples. As long as everyone pays attention to observation, studies diligently and asks questions diligently, there will be unexpected gains.