why do leaves change colors in the fall?

Answer 1

What you are seeing is the underlying color of the leaves when the chlorophyll (green) is gone. That underlying color then deteriorates and oxidizes to become dull and generally brown in time.

Answer 2

The correct answer is Photoynthesis is based on the production of photocells in the plant and the intensity and angle of the light on the plants affects the production in the photocells

In certain regions of the earth (the temperate regions of North and South hemisphere) the angle of the suns rays change in the fall and less intensity of sun light reaches the photocells so the cells produce less

In the tropics the intensity of the sun is relatively the same all year round so there is no change of season

In the arctic and antarctic areas the intensity of sunlight is so sparse very little photosynthesis occurs year-round and generally this is only during a short period of time maybe 4-6 weeks if at all

Answer 3

in the fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food-making process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible and give the leaves part of their fall splendor.

At the same time other chemical changes may occur, which form additional colors through the development of red anthocyanin pigments. Some mixtures give rise to the reddish and purplish fall colors of trees such as dogwoods and sumacs, while others give the sugar maple its brilliant orange.

The autumn foliage of some trees show only yellow colors. Others, like many oaks, display mostly browns. All these colors are due to the mixing of varying amounts of the chlorophyll residue and other pigments in the leaf during the fall season.

Answer 4

the length of time the tree is exposed to the sun does play a part in fall colors, but a drop in temp is the ultimate determinate. for example an oak tree in south florida does not change colors, but the same species in gorgia does. the only variable is the temp. this is simple thermodynamics, as temp goes down (less energy) reactions slow down. it would cost more energy for the tree to facilitate the reaction than it would produce as a result of the reaction. as the temp drops the tree begins to prepare for "hibernation". there are many biological events that occur in this preparation, the most ovious being the change of folage color. the colors you see have always been there, but chlorophyll (in most cases) is the most prevelent and conseals the other pigments. chlorophyll is a very large, unstable molecule, it is constantly breaking down. because of this the tree must constnatly produce more. in the fall the tree stops making it and the leaves lose their green color, exposing the smaller, more stable pigment molecules which are usually shades of red or yellow.

Answer 5

The sun makes trees start the process of photosynthesis, which produces the green pigment...but in the fall, there is less sun, and trees dont go through this process anymore, and so they change color and eventually fall off.

Answer 6

They sense the temperature change which causes a
chemical reaction to prepare the leaves to drop off. The
chemical reaction also causes the color to change.

Answer 7

When they stop producing oxygen they stop being green by the chorophil and that whole process. Then their real colors show up instead.

Answer 8

beacaues the tempreture changes and the trees need the hot wheather to go through photosynthusus and they cant when the wheather gets colder they cant produce their own food so they cant stay green

Answer 9

Lots of good answers, in the end it's their true color showing

Answer 10

Lack of chlorophyll which make the leaves a yellowish coloured as compared to normal greenish coloured.