I know that leafs loose chlorophyll. But my question is why do plants use energy to produce extra accessory pigments usch as xanthophyll after they begin loosing chlorophyll. These pigments are what makes leafs look different colors. I understand the leaf falling off and dying, but why waste energy to change color first? What is the evolutionary force behind this adaptation.
2006-09-12 09:28:51 · 10 answers · asked by nigel 3 in Science & Mathematics ➔ Botany
It is a popular misconception that cold and frost cause the tree to change to its autumn color. A quick frost or freeze only serves to shorten the span of a tree's coloration
As the days shorten and the nights get cooler, a chemical clock kicks in and releases a hormone that slows the sap flow to each leaf. Eventually, the leaf is sealed off from the branch and the green chlorophyll fades away to reveal the different chemical pigments that provide such bright colors
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.
2006-09-12 09:36:56 · answer #1 · answered by pipi08_2000 7 · 3⤊ 0⤋
The plant does not expend extra energy making the accessory pigments. The pigments are there all year round. You can not see them because they are masked by chlorophyll (green) that we see. The pigments are only revealed as the plant reasorbs the chlorophyll. The plant reabsorbs the chlorophyll and breaks it down, in order to use the proteins and molecules for other things.
P.S. - From an advanced degree botanist
2006-09-12 18:59:46 · answer #2 · answered by jalwerdt 2 · 2⤊ 0⤋
Good question. I'm not even close to an expert, and I'm not willing to do any research right now. (In other words, total shot in the dark here - but I'm bored, so here goes.) But I would wager that without the intensity (angle in the sky decreasing) and heat that the sun provides, it probably isn't really "cost effective" (energywise) to keep the photosynthesis process running throughout the year, so it closes up shop, and hibernates (in a way).
The changing colors is simply caused by removal or expiring of chlorophyl, or other chemicals related to the process. This ultimately leaves behind original leaf color - sans chloropyl It happens in predictable regional patterns, because the trigger in it (aside from being regulated internally through a chemical "clock" of sorts) was evolutionarily developed through the angle of the sun, which grardually pulls towards the tropics in winter.
So that's my guess.
2006-09-12 16:40:18 · answer #3 · answered by Yooka 3 · 0⤊ 0⤋
It is not wasting energy, it is saving energy, by not manufacturing chlorophyll, since it will no longer be needed during the winter months during its dormant period. The underlying colors are undoubtedly seen/detected (even when chlorophyll is present) by the more complex vision of insects and some animals (who can see in UV spectra that we can't) who play a role in the life cycle of the plant.
2006-09-12 16:38:11 · answer #4 · answered by finaldx 7 · 1⤊ 0⤋
most of the "extra" pigments are already there and are just masked by the clorophyll. The majority of the Xanthines are used by the plant as insecticides or herbivore protection because they are bitter
2006-09-12 23:02:46 · answer #5 · answered by Anonymous · 1⤊ 0⤋
To let u know winter is coming and it's time to freeze ur butt off!!!
Things die or become dormant in the winter and in the spring new things r grown or bloom; I guess the circle of life
2006-09-12 16:37:11 · answer #6 · answered by wolfpack0810 4 · 0⤊ 0⤋
Usually it is the plant getting rid of it's toxins that it has accumulated, it pumps it into the leaves and then they drop off.
2006-09-12 16:32:01 · answer #7 · answered by lotusbunny 2 · 0⤊ 1⤋
The same reason your hair turns grey! lol
2006-09-12 16:36:51 · answer #8 · answered by Anonymous · 1⤊ 0⤋
It is a natural process, nothing on earth is known to be able to stop it.
2006-09-12 16:34:30 · answer #9 · answered by Administrator 2 · 0⤊ 1⤋
To be pretty- duh...
Lol I have no idea.
2006-09-12 16:32:08 · answer #10 · answered by metallica_rocks0122 6 · 0⤊ 1⤋