why do leaves change colour in autumn?

Answer 1

as u would know autumn comes afted the rainy seoson..and during the rainy seoson the moisture level in our atmoshphere is very high.
and the plants get very less sunlight ...as such they cant make their optimum level of food..and hence mst get dry...it is the moisture which
retains there freshness and colour...by the end of rainy seoson the moisture is also reduced in the atmosphere ...hence the leaves now start changing colour(green owing to chlorophyll) and fall upon..
u may ask that now these plants can have suffiicent sunlight ..but in fact ..these leaves have died much earlier..

jst compare it with a dead person inside a ice container..it looks alive..but take out u will feel that he is dead..

Answer 2

Most trees recover the mineral magnesium from the leaves in the autumn before the leaves drop. Magnesium is in the a key part of the green pigment that makes leaves green. The leaf is alive and helping in the process of storing the magnesium in the woody part of the tree.

It is a very strong pigment and it covers up other colors that are present. The reds and yellows are carotenoids and are related to vitamin A. Well known corotens are alpha-carotene, beta-carotene and lycopene. Lycopene is the red in the tomato and beta-carotene is the bright orange in carrots.

Answer 3

Leaves are nature's food factories. Plants take water from the ground through their roots. They take a gas called carbon dioxide from the air. Plants use sunlight to turn water and carbon dioxide into glucose. Glucose is a kind of sugar. Plants use glucose as food for energy and as a building block for growing. The way plants turn water and carbon dioxide into sugar is called photosynthesis.
in autumn 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.

Answer 4

Leaves change color in only those places where it snows / freezes in winter. Leaves can accumulate snow adding weight to the branches - thereby making the tree vulnerable. SO the tree pro actively shed the leaves, take away precious nutrition from them to store in the main stem / trunk.

Answer 5

they don't

the green just fades, then the anthocyanins and caretenes show up

Answer 6

law of nature... every thin that comes has to go.... they live there life ,, gets dried up nd changes their colour nd fell s frm treee..........................