Why do the leaves turn colour in the fall?

Answer 1

As summer ends and autumn comes, the days get shorter and shorter. This is how the trees "know" to begin getting ready for winter.

During winter, there is not enough light or water for photosynthesis. The trees will rest, and live off the food they stored during the summer. They begin to shut down their food-making factories. The green chlorophyll disappears from the leaves. As the bright green fades away, we begin to see yellow and orange colors. Small amounts of these colors have been in the leaves all along. We just can't see them in the summer, because they are covered up by the green chlorophyll.

The bright reds and purples we see in leaves are made mostly in the fall. In some trees, like maples, glucose is trapped in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn cause the leaves turn this glucose into a red color. The brown color of trees like oaks is made from wastes left in the leaves.

It is the combination of all these things that make the beautiful colors we enjoy in the fall.

Answer 2

This is because the chlorophyll (the green pigment, which also happens to mediate photosynthesis) is deteriorating. This unmasks other pigments that are already present in the leaves but are not seen because the chlorophyll content is so high earlier in the season. When the days get shorter and the temperatures begin to cool, that is when the deterioration of the chlorophyll begins.

Answer 3

It is because the apical meristem goes dormant and nutrients does not go to the leaves anymore. The leaves then turn color and fall off. To help you futher read about senescence. Senescence is the reason why leaves fall off.

Answer 4

It is a lack of carbon dioxide. During the fall months, trees shut down food and CO2 supplies to it's limbs to prepare for the winter. It's kind of like hibernation for trees. The pretty colors we see is actually the leaves suffocating.

Answer 5

they die.......emo tear