Why are plants green?

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It is not an answer as it fail to explain why chlorophyll is used to extract energy as opposed to any number of chemicals.

Your question is based on a false premise.

Chlorophyll is not the only pigment used by plants to extract energy, it's not even true of green plants. Green plants use a range of accessory pigments in conjunction with chlorophyll, specifically to harvest light energy and convert it to something useable, they include:
Carotene - an orange pigment
Xanthophyll - a yellow pigment
Phaeophytin a - a gray-brown pigment
Phaeophytin b - a yellow-brown pigment
 
They are not true leaves and even if they were they fail to answer for the vast majority of plants, which is the question.
This is beginning to smell like creationist trolling (it also sounds like a 'No True Scottsman' Fallacy).

You're going to have to explain how you define a 'true leaf' because (for example) Poinsettias only have one kind of leaf, and they're red.
 
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Well interesting or whatever but it not really an answer as you have to replain why retinal was purple for a start.
It is just shifting the goal posts.

I don't think the chemistry argument is very strong.

Retinal was (and still is) the colour it is because the total length of the conjugated double bond system matches the wavelength of a photon with a wavelength of around 400nm, and so Retinal can absorb photons of this wavelength, and in so doing is excited into a higher energy electronic configuration, however because Retinal absorbs in the blue-green part of the spectrum, it appears red-orange to us. It appears red-orange to us, because our eyes see in three colours (red, green, and blue) or in a very few cases four (predominantly women). Our brain then 'adds' the strength of the responses in these three bands and 'calculates' the colour it is seeing.

We see it as Orange, because what we're seeing is mostly red with a little bit of green and no blue.

Attaching the Retinal to other stuff, as it would have to be to be useable by plants, changes (lowers, in this case, I believe) the wavelength of light that is absorbed, by changing the length of the conjugated double bond system, resulting in a slightly different colour.

EG:
vis3.gif


This is why Rhodopsin (what things using Retinal to make food use) is purple.
 
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This is beginning to smell like creationist trolling (it also sounds like a 'No True Scottsman' Fallacy).

You're going to have to explain how you define a 'true leaf' because (for example) Poinsettias only have one kind of leaf, and they're red.

What make you think it is creationist?

I fail to see the link?

Could you explain how you made that connection?
 
Retinal was (and still is) the colour it is because the total length of the conjugated double bond system matches the wavelength of a photon with a wavelength of around 437nm, and so Retinal can absorb photons of this wavelength, and in so doing is excited into a higher energy electronic configuration, however because Retinal absorbs in the blue-green part of the spectrum, it appears red-orange to us. It appears red-orange to us, because our eyes see in three colours (red, green, and blue) or in a very few cases four (predominantly women). Our brain then 'adds' the strength of the responses in these three bands and 'calculates' the colour it is seeing.

We see it as Orange, because what we're seeing is mostly red with a little bit of green and no blue.

Attaching the Retinal to other stuff, as it would have to be to be useable by plants, changes (lowers, in this case, I believe) the wavelength of light that is absorbed, by changing the length of the conjugated double bond system, resulting in a slightly different colour.

This is why Retinal is purple.

It goes without saying that retinal has the chemical properties that make it appear the colour it is, that is a trivial argument.


I mean it would be a shocker if it had chemical properties which made it appear different colour to what it was.

Intact it would be a miracle!

It's like saying:

Q: Why did the man cross the road?

A: Because he used his legs to transport himself to the opposite pavement.
 
What make you think it is creationist?

I fail to see the link?

Could you explain how you made that connection?
This is a bait and switch - whether or not I think you're a creationist is irrelevant to the discussion.

I posed you a legitimate, relevant, question, "What do you define as a true lead". And you're using the point that I expressed the opinion that your posts were starting to sound like creationist trolling as a distraction to avoid answering it.
 
It goes without saying that retinal has the chemical properties that make it appear the colour it is, that is a trivial argument.


I mean it would be a shocker if it had chemical properties which made it appear different colour to what it was.

Intact it would be a miracle!

So then the answer to your question "Why is Retinal purple" is "Because of its physico-chemical properties", and you accept that as an answer.
 
This is a bait and switch - whether or not I think you're a creationist is irrelevant to the discussion.

I posed you a legitimate, relevant, question, "What do you define as a true lead". And you're using the point that I expressed the opinion that your posts were starting to sound like creationist trolling as a distraction to avoid answering it.

Sounds to me like you are trolling mate.

Unless you can explain your creationist point I don;t see why I shououdl answer, however I will.

I don't think you yourself know why you made the creationist point and that's probably why you can't make an answer. OR at least in trying to say why you realised how stupid your point was.

Anyway I am not interested in one or two obscure plants I am interested in the other 99.9% of plants.

I can change my question to "most plants" rather the "plants" is you are going to nit-pick.
 
So then the answer to your question "Why is Retinal purple" is "Because of its physico-chemical properties", and you accept that as an answer.

Only in the most trivial sense.

It is not an answer in the context of the question I originally asked.
 
Sounds to me like you are trolling mate.

Unless you can explain your creationist point I don;t see why I shououdl answer, however I will.

I don't think you yourself know why you made the creationist point and that's probably why you can't make an answer. OR at least in trying to say why you realised how stupid your point was.

Anyway I am not interested in one or two obscure plants I am interested in the other 99.9% of plants.

I can change my question to "most plants" rather the "plants" is you are going to nit-pick.

Have you got some sort of problem? When someone asks a question it usually is because then are seeking an answer. Sometime it is because they are seeking a confrontation. You seem to be of the latter.

It would seem that you have a view point on this; perhaps you could try being honest and share your view.

Or you can buzz off, I personally don't feel like playin your little game....:rolleyes:
 
Have you got some sort of problem? When someone asks a question it usually is because then are seeking an answer. Sometime it is because they are seeking a confrontation. You seem to be of the latter.

It would seem that you have a view point on this; perhaps you could try being honest and share your view.

Or you can buzz off, I personally don't feel like playin your little game....:rolleyes:

I think you should forget the all the personal issues you have about the question and just see it for what it is, a question.

If you can answer it fine, if you can't that's fine too.
 
How do you now he has a favourite colour?

It was a joke...I'm an atheist. :)

I'm not a biologist...but if I had to try to answer your question about why plants use chlorophyll and not some other chemical, is because billions of years ago, some "proto-plant" first used chlorophyll and was highly successful and prospered while others did not. It survived and gave rise to all other chlorophyll using plants, as it was such a beneficial mutation.
 
Sounds to me like you are trolling mate.
No trolling involved, on my behalf at any rate.

Unless you can explain your creationist point I don;t see why I shououdl answer, however I will.
I've already explained that it's not directly relevant, simply an opinion reflecting on the language you've used so far. Move on.

I don't think you yourself know why you made the creationist point and that's probably why you can't make an answer. OR at least in trying to say why you realised how stupid your point was.
This, is trolling. Not to mention ridiculous. I know exactly why I made the comment, and won't answer is not the same as can't answer. One does not imply the other.

Anyway I am not interested in one or two obscure plants I am interested in the other 99.9% of plants.
Which would be great if I were only talking about a minority of plants, but I'm not.
EVERY SINGLE PLANT, for example, contains caretenoids of some form, to some extent. The also contain each and every single on of the other pigments I named, in varying degrees and combinations, this is why plants are so many different shades of green.

I can change my question to "most plants" rather the "plants" is you are going to nit-pick.
Your question has been answered, however.
Q: Why are plants green?
A: Because of Chlorophyll.

Q: Why is Cholorphyll green?
A: Because Chlorophyl contains a cyclic conjugated double bond system, which has a magnesium ion bound to it (as a ligand). It's green because the total length of the conjugated system matches the wavelength of a red photon.

Q: Why do modern plants use Chlorophyll for photosynthesis?
A: Perhaps Plants using chlorophyll had to compete with plants using pigments that absorbed in the green portion of the spectrum, and chlorophyll outcompeted them because it was more efficient at converting energy into food.
Perhaps the over abundance of energy in the part of the spectrum is detrimental.
Perhaps the different atmospheric chemistry of the early earth (at the time Autotrophs evolved) scattered and absorbed light differently from what is observed now - resulting in red light being the most widely available light source at ground level.
Perhaps absorbing only low energy radiation reduced early mortality - the early atmosphere may have been a lot more transparent to Higher energy frequencies, which do more damage (this is related to why colours fade with time). This has the advantage of explaining why plants incorporate the auxillary pigments they do - they all absorb strongly in the UV/Blue end of the spectrum, some of them have anti-oxidant properties, and none absorb in the green portion. This has the net effect of protecting Chlorophyl from the damaging high energy radiation (Chlorohyll also absorbs in the Blue/UV part of the spectrum), as well as protecting it (and the rest of the cell) from the effects of damage that is done.
Perhaps a combination of all of the above.
Perhaps none of the above - at this point, all we can really do is speculate, and through that speculation we can't rule out the existence of multiple photosynthetic pathways in the early history of the earth, using a variety of pigments, the only thing we can say for certain is that there was some environmental factor that meant that those organisms using chlorophyl based photosynthesis were more successful than the others.

Q: Why aren't the pigments that plants use black?
A: Because pigments that absorb across the whole electromagnetic spectrum degrade very quickly (related to the penultimate point above).
 
EVERY SINGLE PLANT, for example, contains caretenoids of some form, to some extent. The also contain each and every single on of the other pigments I named, in varying degrees and combinations, this is why plants are so many different shades of green.

Your question has been answered, however.
Q: Why are plants green?
A: Because of Chlorophyll.

Q: Why is Cholorphyll green?
A: Because Chlorophyl contains a cyclic conjugated double bond system, which has a magnesium ion bound to it (as a ligand). It's green because the total length of the conjugated system matches the wavelength of a red photon.

Q: Why do modern plants use Chlorophyll for photosynthesis?
A: Perhaps Plants using chlorophyll had to compete with plants using pigments that absorbed in the green portion of the spectrum, and chlorophyll outcompeted them because it was more efficient at converting energy into food.
Perhaps the over abundance of energy in the part of the spectrum is detrimental.
Perhaps the different atmospheric chemistry of the early earth (at the time Autotrophs evolved) scattered and absorbed light differently from what is observed now - resulting in red light being the most widely available light source at ground level.
Perhaps absorbing only low energy radiation reduced early mortality - the early atmosphere may have been a lot more transparent to Higher energy frequencies, which do more damage (this is related to why colours fade with time). This has the advantage of explaining why plants incorporate the auxillary pigments they do - they all absorb strongly in the UV/Blue end of the spectrum, some of them have anti-oxidant properties, and none absorb in the green portion. This has the net effect of protecting Chlorophyl from the damaging high energy radiation (Chlorohyll also absorbs in the Blue/UV part of the spectrum), as well as protecting it (and the rest of the cell) from the effects of damage that is done.
Perhaps a combination of all of the above.
Perhaps none of the above - at this point, all we can really do is speculate, and through that speculation we can't rule out the existence of multiple photosynthetic pathways in the early history of the earth, using a variety of pigments, the only thing we can say for certain is that there was some environmental factor that meant that those organisms using chlorophyl based photosynthesis were more successful than the others.

Q: Why aren't the pigments that plants use black?
A: Because pigments that absorb across the whole electromagnetic spectrum degrade very quickly (related to the penultimate point above).

Why do I get the strong feeling that esbo will say this excellent answer is also wrong?
 
It was a joke...I'm an atheist. :)

I'm not a biologist...but if I had to try to answer your question about why plants use chlorophyll and not some other chemical, is because billions of years ago, some "proto-plant" first used chlorophyll and was highly successful and prospered while others did not. It survived and gave rise to all other chlorophyll using plants, as it was such a beneficial mutation.

So why were they highly successful?

Care to explain?
 
This is beginning to smell like creationist trolling (it also sounds like a 'No True Scottsman' Fallacy).

You're going to have to explain how you define a 'true leaf' because (for example) Poinsettias only have one kind of leaf, and they're red.

That is what I was thinking , A Creationist bate and switch
 
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