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Author Topic: Why do leaves change colour?  (Read 5770 times)

Offline cuso4

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Why do leaves change colour?
« on: 27/02/2006 19:24:41 »
Why do leaves of some plants change colour in autumn? I know it's somthing to do with singlet oxygen affecting the chlorophyll in leaves but I can't remember exactly. If someone can help me out it will be great.

Angel


 

Offline AlphBravo

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Re: Why do leaves change colour?
« Reply #1 on: 27/02/2006 22:57:01 »
Is it not that leaves have died and being a good conserver of moisture and resources etc, the tree is preparing to endure the winter, sans leaves. which have dropped onto the ground thus being used as some sort of a mantle, and nutrient for the tree/s for the next summer.
 

Offline Broca

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Re: Why do leaves change colour?
« Reply #2 on: 28/02/2006 00:32:37 »
During the spring and summer the leaves have served as factories where most of the foods necessary for the tree's growth are manufactured. This food-making process takes place in the leaf in numerous cells containing chlorophyll, which gives the leaf its green
color. This extraordinary chemical absorbs from sunlight the energy that is used in transforming carbon dioxide and water to carbohydrates, such as sugars and starch.

Along with the green pigment are yellow to orange pigments, carotenes and xanthophyll pigments which, for example, give the orange color to a carrot. Most of the year these colors are masked by great amounts of green coloring. But 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.

copied from this site.
http://www.esf.edu/pubprog/brochure/leaves/leaves.htm

 

Offline ariel

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Re: Why do leaves change colour?
« Reply #3 on: 28/02/2006 01:10:15 »
I thought it was because the wavelengths of light are being bent differently in the different seasons (different color of leaves in different seasons) because the earths axis is changing in relation to the sun;

and the different wavelengths the chlorophylls absorb determine their color.

but, I am not too sure, this is just memory of what someone told me

:D

now i actually am curious if this is true
 

Offline cuso4

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Re: Why do leaves change colour?
« Reply #4 on: 28/02/2006 11:17:31 »
thank you Broca :)

Angel
 

Offline DoctorBeaver

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Re: Why do leaves change colour?
« Reply #5 on: 28/02/2006 20:18:42 »
It's all down to sugars. Don't argue with me because that's a fact [:o)]
 

Offline chris

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Re: Why do leaves change colour?
« Reply #6 on: 01/03/2006 10:02:02 »
This was discussed on a radio show a year or so ago.

http://www.nakedscientists.com/HTML/Shows/2003.11.09.htm#1

Leaves change colour because the chlorophyll - which is green - breaks down and is not replaced. As this dominant green pigmentation disappears it ceases to mask the other coloured pigments naturally present in the leaf which including oranges, pinks and reds produced by anthocyanins and carotenoids (amongst other things).

So with the disappearence of the cholorophyll the other colours are disclosed.

Chris

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Offline DoctorBeaver

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Re: Why do leaves change colour?
« Reply #7 on: 01/03/2006 14:09:36 »
Sugars
 

Offline neilep

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Re: Why do leaves change colour?
« Reply #8 on: 01/03/2006 18:14:35 »
Leaves are emotional, they get embarrassed and also blush...forget the science...this is the real reason.

Men are the same as women.... just inside out !!
 

Offline DoctorBeaver

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Re: Why do leaves change colour?
« Reply #9 on: 04/03/2006 13:51:19 »
Have you been at the sherry again?

So when a leaf runs out of chlorophyll, does that make it chloroempty?
 

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Re: Why do leaves change colour?
« Reply #9 on: 04/03/2006 13:51:19 »

 

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