Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: jaclin on 19/10/2008 13:17:21
-
jaclin asked the Naked Scientists:
Do the green leaves of a plant absorb green light during photosynthesis?
What do you think?
-
Hi Jaclin - no, it's the other way around. They do not absorb the green light, which is why you can see them. Black things absorb pretty much all the lightwave frequencies, whilst white things reflect pretty much all the frequencies. The apparent colour of anything is determined by what it reflects and which you can therefore see, not what it absorbs.
(reflection and absorption - Of course you could say that the two are mutually inclusive)
I'm sure that I wrote a thread about photosynthesis some time ago - let me have a look.
-
Here's a snippet
Chlorophyll absorbs light and provides the energy for photosynthesis. The wavelength in which chlorophyll works best is in the red and blue range, and therefore does not absorb the green wavelength which is why leaves appear green. There are 2 chlorophylls at work - "a" and "b". They both operate in a slightly different frequency, thus increasing the total energy use from the sun. Chlorophyll "a" operates in the 400-450 & 650-700 nm frequencies (purple and red) while "b" operates in the 450-500 & 600-650 nm frequencies (blue and orange). They also generally exist in a 3 to 1 ratio, a to b. The gap left (500 - 600 nm) is the green zone. In some tree's leaves, the chlorophyll "a" is less dominant, therefore there is an increase in the anount of purple and red wavelengths reflected, hence the leaves are more purpley in colour, while the tree is still able to photosynthesize.
-
jaclin asked the Naked Scientists:
Do the green leaves of a plant absorb green light during photosynthesis?
What do you think?
Of course they do!
In the dark forest you can see the grass, which grows purely on green light, because only this spectrum can pass through trees partly unabsorbed.
Besides the chlorophyll, plants have other pigments, which take part in photosynthesis too. The color of this pigments you can see in the autumn.
-
jaclin asked the Naked Scientists:
Do the green leaves of a plant absorb green light during photosynthesis?
What do you think?
Of course they do!
In the dark forest you can see the grass, which grows purely on green light,.......
Please can you provide sources for this? Thankyou!
-
Here is a nice and informative website about photosynthesis:
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html#Table%20of%20Contents
About halfway down you can see a diagram that shows the light frequency useage, and that the chlorophyll a and b drop to virtually nothing in the mid range, and hence this is the reflected light - green. My expertise does not lie in forest-floor grasses, but even in the most dense canopy situations, there is still light which is not purely green. If the only light was green, and the grass used this to photsynthesis, it would appear black as the green light was being absorbed. Since grass is green, it seems reasonable to me to assume that this is the light that is being reflected. A dark forest may be dark, but there is still photosynthetically active radiation reaching the forest floor, which the grass is using to photosynthesise.
-
Usually, in the books we can see the absorb spectrum of the native pigment.
But in reallife, in nature, the plants pigments, such as chlorophyll, is in the complex mode with other pigments and structure, therefore the absorb spectrum of chloroplast (min. unit of photosynthesis) and leaf can be more full.
In chloroplast: http://4e.plantphys.net/image.php?id=72
vital chlorella: http://www.biologie.uni-hamburg.de/b-online/e24/10.htm
In your image
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.emc.maricopa.edu%2Ffaculty%2Ffarabee%2FBIOBK%2Fabsorspect.gif&hash=b4a983efe70061deb1877ca2b7697b28)
we can see that the green light worse absorbed only in 3times, therefore this spectrum of light is more important in the depth of forest…
P.S.
absorption spectrum soya`s leafs
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fmsaqua.com%2Fpics%2Faqua%2Flamps%2Fsoy_spec.gif&hash=8210c09535d20d4ea47d90c48af26630)
-
In the dark forest you can see the grass, which grows purely on green light, because only this spectrum can pass through trees partly unabsorbed.
If there were only green light available on the forest floor, you would not be able to see any other colours at all. The light is greenISH but there is still enough red and blue to provide colour vision (I have seen many coloured photos taken in deep forests) and some photosynthesis. Forest floor plants don't actually grow very well because they don't get a lot of energy.
-
jaclin asked the Naked Scientists:
Do the green leaves of a plant absorb green light during photosynthesis?
What do you think?
Of course they do!
In the dark forest you can see the grass, which grows purely on green light, because only this spectrum can pass through trees partly unabsorbed.
Besides the chlorophyll, plants have other pigments, which take part in photosynthesis too. The color of this pigments you can see in the autumn.
The light that reaches the forest floor is the light that has passed between the leaves, branches, etc, of the forest canopy. not much light actually goes straight through the leaves. So the light that reaches, and nourishes, the grass is mostly white. to check this go into the forest and look at a piece of white paper. If the paper looks like the green section of the light spectrum, I'm wrong.
-
jaclin asked the Naked Scientists:
Do the green leaves of a plant absorb green light during photosynthesis?
What do you think?
Of course they do!
In the dark forest you can see the grass, which grows purely on green light,.......
Please can you provide sources for this? Thankyou!
https://www.google.com.au/search?pq=which+plants++absorb+green+light&hl=en&cp=11&gs_id=23&xhr=t&q=red+leaf+plants&client=ubuntu&hs=rEb&channel=cs&gs_upl=&bav=on.2,or.r_gc.r_pw.,cf.osb&biw=1024&bih=682&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=uP44T7GXMIyziQf605DyAQ (https://www.google.com.au/search?pq=which+plants++absorb+green+light&hl=en&cp=11&gs_id=23&xhr=t&q=red+leaf+plants&client=ubuntu&hs=rEb&channel=cs&gs_upl=&bav=on.2,or.r_gc.r_pw.,cf.osb&biw=1024&bih=682&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=uP44T7GXMIyziQf605DyAQ)