Ответы и объяснения

All summer long, a tree’s leaves have been making food for the tree so it can grow. An amazing chemical in the leaves, called chlorophyll, uses sunlight to turn carbon dioxide and water into the tree’s breakfast, lunch and dinner.   Chlorophyll gives the leaves their green color.  Also in the leaves are other chemicals with yellow and orange colors—the same chemicals that give color to some flowers, carrots, and even bananas.  You don’t see those colors in summer because there is so much green chlorophyll in the leaves hiding the other colors. In the winter, the short days don’t provide enough sunlight for the trees to make their food, so the trees live off the food they stored during summer.  Before winter arrives, the shorter days make the trees slow down their food making, and the green chlorophyll disappears from the leaves.  That’s when the yellow and orange colors take over.  At the same time, other chemical changes may happen in the leaves, forming other colors such as red or purple.  Like an artist mixes paint for his canvas, the chemicals mix to form different colors in different trees. Eventually some trees, but not all, lose their leaves.