Talk:Photosynthesis

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Wavelength...

In one of the last sections, "Light intensity (Irradiance), wavelength and temperature", the question of wavelength looks like it will (finally, after having been neglected the entire article) addressed. But this does not actually happen. Something needs to be added about what wavelengths are necessary for photosynthesis to work. You can't grow a plant using a typical incandescent bulb, but you can if you use a fluorescent one producing even fewer lumens. It's not simply light level and heat which is important, but also (or perhaps most importantly) frequency. This needs to be inserted, perhaps even with an additional summary near the top. Kaz 22:33, 4 January 2007 (UTC)

Algae and low-light plants (java moss, and najas grass) grow just fine in my fish tanks with just an incandescent or halogen bulb. But they grow better with a florescent bulb. Just an FYI. 64.199.9.162 (talk) 17:51, 19 January 2009 (UTC)

Other photosynthesis

Don't humans photosynthesise vitamin D from sunlight? I originally thought it was like photo- osmosis, but that wouldn't work. I then found out that sunlight is used to make vitamin D in the skin. So using light to create things = photosynthesis. And that is what humans do. I think maybe other animals do something similar? Cheesypot 23:09, 12 January 2007 (UTC)

Bold text== Quantasomes ==

what is called a photosystem on the page should correctly be named as a quantasomes as they are the smallest structural unit of photosynthesis on the thylakoid membrane and it is the Quantasomes which contain the chlorophyll and cytochromes.

being called a photosystem is partially correct but it is within the Quantasome that the photosystem is contained. but not the name of the actual component

the line reading "light dependent reactions occur in the thylakoid membranes of the chloroplasts"

should correctly be "The light dependant reactions occur in the quantasomes on the thylakoid membranes in the chloroplast"

and the image anatated as "A Photosystem: A light-harvesting cluster of photosynthetic pigments present in the thylakoid membrane of chloroplasts."

should be "A Quantasome: present on the thylakoid membrane, Containing the Photosystem - A light-harvesting cluster of photosynthetic pigments." —The preceding unsigned comment was added by Mauller95 (talk • contribs) 18:29, 21 January 2007 (UTC). heloo pople

Vandalism magnet

Why exactly is the Photosynthesis article semi-protected again? I mean, it's not even a religious or political topic! I can't believe that someone has a bone to pick with the idea of photosynthesis. Seriously, what the heck!? [[

H2S To Sulfur Photosynthesis / Archaea

I noticed that this article talks about the hydrogen sulfide to sulfur photosynthesis process as being performed by bacteria. However, in my poking around on the subject Encarta claims that this process is performed by the bacterialike archaea instead.

Not being anything like a biologist I can only throw this out as confusion on my part in hopes that someone could clarify. I do believe that these days the archaea are not at all regarded as bacteria, being in an entirely different family, though some do hedge and refer to them as "archaebacteria". MrG 4.227.250.35 22:56, 3 February 2007 (UTC)

Nature Paper - appearance of oxygenic photosynthesis

I Draw page author’s attention to the recent paper in Nature by Allen and Martin (Vol445, number 8, pgs610-612), titled, “Out of thin air”. It nicely reviews alternative theories for when oxygenic photosynthesis appeared on earth. They further describe a hypothetical proto-cyanobacterium expressing both types of photosynthesis, and which might still be extant. SNP 19:49, 8 February 2007 (UTC)

General Equation for photosynthesis

I just added a reference to the general equation, any disputes will be reverted unless you provide a credible source or logic (experimental evidence would be good too). -68.75.17.218

It can be confusing. I remember in my high school textbooks when the older, "balanced" equation was used and taught. But as a biology major, I learned that in the Calvin Cycle of sugar synthesis, the six oxygen atoms that are liberated from the plant don't come from the carbon dioxide it "breathes", but actually comes from water molecules that the plant uses as a reactant in photosynthesis. Because each water molecule has only one oxygen atom, the plant will need twelve molecules to fully complete the cycle. Later on in photosynthesis, six water molecules are also products. This occurs during carbon fixation, in which the carbon dioxide is built together into a sugar molecule and hydrogen ions are used to turn reactive oxygen atoms that go flying off into useful water molecules that can be used again by the plant as soon as the cycle completes.

In the future, you might want to add new topics on the Talk page at the bottom of the page, as that is where most users will check for the most recent additions. And you can easily sign comments by using four tildes (the ~ character) at the end of your comments. I hope this helps!--Ryan! 06:04, 5 March 2007 (UTC)

atmospheric carbon sequestration capacity

Is there any study related to the measurement of carbon absorption by plants in hydroponic cultures inside greenhouses, excluding all organic matter in the nutrient solution ? If we have on average 200ppm to 400ppm (or about 400mg of C02 per m3 of air) of carbon dioxide in the atmosphere, how much of that could be absorbed, on a daily basis, by one square meter of cultivated land? Does this absorption occur only when air passes through the leaves or are the carbon dioxide molecules attracted to the leaves' surface by some other selective "mechanism", binding CO2 molecules in something like a string that is pulled by such a process ? This question may sound silly, but if all air had necessarilly to be "filtered" by the leaves in order to allow them to absorb the CO2, this would IMO imply a less efficient process than one that could bind free CO2 molecules dispersed in a small concentration in "lots" of air and then "pull" them towards the leaves... --Dfv10 02:58, 15 March 2007 (UTC)

Corollary factors?

What is this section supposed to be about? It only consists of a header line and a stub notice, but I wouldn't even know what to put in there if I wanted to expand it. Does anyone have an idea what "corollary factors" is supposed to summarize in the context of photosynthesis? - tameeria 18:21, 3 April 2007 (UTC)

Equation

There has been the repeated addition of "catalysts" to the equation of photosynthesis now. Is there any reliable reference for that? All references I have don't list "catalysts" at all. E.g.:

• Campbell & Reece: Biology, 7th Edition:

6 CO₂ + 12 H₂O + light energy → C₆H₁₂O₆ + 6 O₂ + 6 H₂O (equation for glucose; also listed in Freeman and Brooker)

• Freeman: Biological Science, 2nd Edition:

CO₂ + 2 H₂O + light energy → (CH₂O)_n + H₂O + O₂ (general equation)

• Brooker et al.: Biology, 1st Edition:

CO₂ + 2 H₂O + light energy → (CH₂O)_n + H₂O + O₂ (general equation)

• Raven et al.: Biology of Plants, 7th Edition:

CO₂ + H₂O + light energy → (CH₂O) + O₂ (general equation)

• Berg: Introductory Botany, 2nd Edition:

6 CO₂ + 12 H₂O (+ light energy, chlorophyll) → C₆H₁₂O₆ + 6 O₂ + 6 H₂O

= Carbon dioxide + Water (+ light energy, chlorophyll) → Glucose + Oxygen + Water

While we're at it, where is the "gas", "aequous" and "liquid" in the equation coming from? Is this sourced from a particular textbook? If so, a reference should be added, but I haven't found any yet that actually list that in their equations (see above for the ones I did find). - tameeria 02:12, 25 April 2007 (UTC)

Please provide a reference when changing equations. If it is changed from what it is now, chances are high that the result is something that cannot be found in textbooks. Therefore chances are high it is going to be reverted unless a reliable, verifiable reference for the new equation is provided with the edit. - tameeria 03:07, 8 May 2007 (UTC)

Photosynthesis equations

First of all the initial equation is wrong. You can't just make oxygen and sugar from water and carbon dioxide. What you need is a catalyst. I don't know why no one else bothered to put this into their equations but it is absolutely necessary in my oppinion. I have tried to proceed the given equation by just shining light on carbonated water but it obviously doesn't work. 68.252.36.107 03:35, 8 May 2007 (UTC)

The equation is not wrong. Not all equations have the catalyst. Where is that precedent coming from? David D. (Talk) 04:06, 8 May 2007 (UTC)

An encyclopedia is a collection of information that was published in other sources. Personal opinion doesn't fit that description. And the second point sounds suspiciously like original research... ;) I can see the point you're trying to make, but unless you can provide a published reference for your equation, it is unlikely to find acceptance as it stands against several textbook equations. In general, it seems to be more conventional that biochemical reactions like this are written as just reactants and products without adding the enzymes (catalysts) to the equation of the reaction. - tameeria 04:11, 8 May 2007 (UTC)

Glucose is NOT ever an end-product of photosynthesis

Dear Colleagues

It is really unfortunate that the ancient text-book error in photosynthesis that considers glucose is the end-product of photosynthesis is again repeated here. It is important to re-affirm that glucose is never an end-product of photosynthesis. The end-product of the carbon dioxide assimilation pathway is triose phosphate, a product that is then used to produce either sucrose or starch or provide carbon skeletons for other assimilations. As the date of the 14th International Photosynthesis Congress approaches, it is crucial that we eliminate this error from the definition and from future teaching materials so that no future generations get mislead by an incorrect oversimplification of this crucial process.

Christine H. Foyer (Chair of the Organising Committee of the 14th International Photosynthesis Congress).

The above comment is most probably a bona fide intervention from a real super expert in the field. I find it very unfortunate that it has been left without a proper response. I came here to look for just this kind of comment (because of a discussion about metabolism). To my understanding the (glucose) statement should at least be weakened to say that the first energy storing molecules produced by photosynthesis are used for several different things. I will check a reasonably modern biochemistry book to see if glucose is said to ever be produced. But I really hope someone beats me to it. --Etxrge (talk) 18:19, 20 December 2007 (UTC)

Oxygen is a product of photosynthesis

Dear Colleagues

I find it hard to believe that anyone would consider oxygen to be a waste product of photosynthesis as stated in the present text. Oxygen is a true product of the process. I hope that this error can be corrected as soon as possible. Oxygen production by photosynthesis is a key component of the global oxygen cycle.

Christine H. Foyer (Chair of the Organising Committee of the 14th International Photosynthesis Congress).

It may be part of the global oxygen cycle, but it's a waste product as far as the plant is concerned (assuming a plant could be concerned with anything). Carbon Dioxide is a waste product of animal respiration, the fact that it is needed by plants doesn't change this.--RLent 17:18, 20 September 2007 (UTC)

I definitely agree with C.H. Foyer. Plants do respiration as well as photosynthesis; therefore, oxygen is not a waste product.--Chinoadidas (talk) 03:04, 7 December 2007 (UTC)

I don't understand the logic, just because it is a substrate for respiration does not mean that overall it is not a waste product for a plant or algae. It all depends on the perspective. Ecological or organismal. Don't you consider CO₂ a waste product of animals despite the fact that there are carboxylation reactions in cells? David D. (Talk) 03:18, 7 December 2007 (UTC)

Calling anything a "waste" product is a bit strange. Water is a product of respiration, but is this a "waste product"? This term has no real biochemical meaning except for such things as D-lactate, which is produced from methylglyoxal and has no further possible metabolic role in an organism. Tim Vickers (talk) 04:49, 7 December 2007 (UTC)

I agree waste sounds strange but the I can understand sentiment. Is CO₂ a waste product? I think the emphasis here is that the plant is not producing O₂ for our pleasure. Or its own for that matter. Maybe byproduct is the best description? David D. (Talk) 04:58, 7 December 2007 (UTC)

Just say "product" and be done with it, after all, below the compensation point, oxygen is consumed, not produced. Tim Vickers (talk) 05:26, 7 December 2007 (UTC)

Or more to the point at night. But still, overall the plant gives off oxygen, that is a logical rationale for using waste. Either way i think this is a minor issue. More important is to ensure the major misconception that plants do not respire is not reinforced in the confusion. David D. (Talk) 06:33, 7 December 2007 (UTC)

Very true. Tim Vickers (talk) 22:10, 7 December 2007 (UTC)

equations in overview

I have replaced the balanced (simplified) equations. The equations as written are what is generally seen in an introductory text (the second is cited as such). Now, if the product is written as triose phosphate, which is not C3H6O3, then the reactant side of the equation must include P. So either replace the first with a correctly balanced phosphate including equation - or leave as is in the overview and present the details later. As most readers are not biologists, keep the initial equations as the perhaps familiar ones - noting the shortcomings and continuing with the more complex equations later. Vsmith 03:09, 16 June 2007 (UTC)

Agreed. Thanks for spotting the mismatched equations. Clicketyclack 08:09, 16 June 2007 (UTC)

Potential image

I planted popcorn this year, and ten stalks were white! They were successful for a short time, then they all died - I suspect they could not perform photosynthesis properly. Is there any interest in the photographs that I took? Is there any interest in seed samples (we haven't popped all the popcorn seeds yet)? Is there such a thing as albino plants? Royalbroil 19:03, 22 June 2007 (UTC)

Neat! And yes, they are actually called "albino plants," at least in the case of Arabidopsis and barley albino seedlings, which I know are used in research. They usually die (unless grown on sugar medium) once they've used up all the resources stored in the seed because they cannot photosynthesize. The albino phenotype in plants is a severe form of chlorosis, so I think your pictures might be best placed as illustrations for that article rather than here? - tameeria 20:33, 22 June 2007 (UTC)

I was guessing that they survived until they used up the resources in the seed. I will upload an sample image and place it in the chlorosis article. Thanks for pointing me in the right direction! Royalbroil 01:34, 23 June 2007 (UTC)

Photosynth

Is it ever called "Photosynth"? Coz, if not, I am thinking of removing it from the Photosynth (disambiguation) page. --soum ^talk 07:07, 30 June 2007 (UTC)

Photosynthesis Defn

It is a complex process occurring in higher plants, phytoplankton, algae, as well...

just a question. Does it occur only in higher plants or all plants? --Muhammad Mahdi Karim 16:10, 24 October 2007 (UTC)

I think the word higher is to used to contrast it with some algae that are considered "lower plants". --Kupirijo (talk) 09:30, 10 June 2008 (UTC)

Also I am going to remove phytoplankton because it is redundant, as the words algae and cyanobacteria cover it. --Kupirijo (talk) 09:30, 10 June 2008 (UTC)

Importance of photosynthesis for technologies

Hi. Some of us are trying to work up Solar energy, currently GA, to FA. We need a good reference for the idea that all the food humans eat, wood they use, and fossil fuels they use are the products of photosynthesis. Do you know a source that mentions this? I wondered whether it might be worth adding a very brief section to the photosynthesis article about the importance of photosynthesis to humans and their technologies. Thanks very much in advance. Itsmejudith 19:24, 11 November 2007 (UTC)

I'd imagine any intro biology book says this. I have World of the Cell (Beckker et al.) here and their quote is: "Nearly all life on Earth is sustained, directly or indirectly, by the sunlight that continuously floods our planet with energy." The exception are the communities that rely on the bacteria in black smokers to sustain life. Those bacteria get all their energy from the oxidation of chemicals that comes from the black smokers. Practically none of the suns energy is used in those hydrothermal vent communities. David D. (Talk) 19:51, 11 November 2007 (UTC)

Glucose is NOT ever an end-product of photosynthesis (repeat headline from above)

From Biochemistry, by Campbell and Farrel, 2006, (Thomson Brooks/Cole), p 619, "the carbohydrates produced from carbon dioxide by photosynthesis is not glucose ...". --Etxrge (talk) 19:41, 21 December 2007 (UTC)

Most of the text is correct, it's the equations that need to be fixed. David D. (Talk) 19:47, 21 December 2007 (UTC)

wording on efficiency:

6) Efficiency: The article states: “Plants convert light into chemical energy with a maximum photosynthetic efficiency of approximately 6%.[16]”

I think it would be much more accurate to reword the above to : Plants convert total incident light energy into fixed energy storing biomass at an efficiency of 6%

The rewording is necessary because if you take the portion of the light that is absorbed by the chlorophyll more than 95% is, in fact, converted to chemical energy.

http://www.lbl.gov/Science-Articles/Archive/PBD-quantum-secrets.html

So the actual conversion of light to chemical energy is remarkably efficient, its just that : light is reflected off the leaves, much of the resultant chemical energy is used for respiration etc. , and so never makes it to stored carbohydrates .

Photosynthesis isn’t 6% efficient at turning light into chemical energy its almost 100% efficient.

Chem teacher (talk) 22:42, 19 January 2009 (UTC)

The Wikipedia article is seriously outdated in failing to mention the 2007 breakthrough in understanding how photosynthesis achieves its nearly 100% energy transfer efficiency through use of quantum coherence effects, as documented in the April 12, 2007 issue of Nature. See "Quantum Secrets of Photosynthesis Revealed" at http://www.lbl.gov/Science-Articles/Archive/PBD-quantum-secrets.html for news of this very remarkable discovery.

The Wiki article is also hilariously ridiculous in implying that our current solar panel technology is several times more efficient than photosynthesis! See the same article I cite for a projection that we can eventually develop efficient artificial photosynthesis on par with nature's by learning "huge lessons" about how photosynthesis incorporates quantum effects.

74.250.226.81 (talk) 03:00, 28 February 2009 (UTC)

90 percent efficiency quote (reference 4) is incorrect

If you check the citation for that quote (http://www.sciencenews.org/articles/20070414/fob5.asp), you'll find that it now has an erratum posted, which says (and I quote): "This article incorrectly states that plants "use up to 90 percent of the light that strikes them." Photosynthetic organisms can use more than 90 percent of the energy they absorb, but the absorbed photons are a small percentage of those that strike an organism." This should be corrected, but I don't have an account; can someone who does please correct it? -- Brooks, 09 April 2008. —Preceding unsigned comment added by 64.81.73.35 (talk) 18:15, 9 April 2008 (UTC)

(Also, it should be noted that the sentence in question here is directly copied from the Science News article, which is of course plagiarism and needs to be fixed anyway.) -- Brooks —Preceding unsigned comment added by 64.81.73.35 (talk) 18:18, 9 April 2008 (UTC)

I've rewritten this, can you check my new version? Tim Vickers (talk) 18:27, 9 April 2008 (UTC)

Fructose is not a disaccharide

1st paragraph Overview New to contibuting so do not want to change myself. If someone/everyone agrees pleas change. Nzmach1 (talk) 18:11, 16 April 2008 (UTC)

Thank you, corrected. Tim Vickers (talk) 19:22, 16 April 2008 (UTC)

tiny typo

Molecular production,Temporal Order "The overall process of photosynthesis takes place in four stages. The first, energy tranfer in antenna chlorophyll takes place in the femtosecond " needs an "s" in transfer ... there is a lock to stop people editting

Oxygen is a product of PSII

I cannot believe that such a basic error would remain for such a long time. I have changed the sentence to be: Oxygen is a product of the light-driven water-oxidation reaction catalyzed by photosystem II

It is not a product of PSI, but of PSII.

My friend has actually used this mistake as an example of how you should have a critical approach towards Wikipedia articles. Neyne (talk) 19:43, 15 May 2008 (UTC)

Well it was there for a month after these edits. It looks more like a typo than anything and it's far from a consistent mistake throughout the article. Even textbooks have typos like this. Not that I'm trying to defend wikipedia, because it is these kinds of issues that are a real time sink with regard to maintaining the quality of articles. While text books do have errors, once they are caught they are gone for good. But at wikipedia there is a need to be forever vigilent. David D. (Talk) 04:15, 16 May 2008 (UTC)

"nearly all life on Earth either directly or indirectly depends on it."

What life does not? --AnotherSolipsist (talk) 02:52, 12 June 2008 (UTC)

Chemolithotrophic organisms, such as the bacteria and tube worms around hydrothermal vents. Tim Vickers (talk) 04:32, 12 June 2008 (UTC)

Even organisms near hydrothermal vents are subject to the carbon flux delivered from higher in the water column. Interestingly, even some of the bacteria that live near hydrothermal vents are obligately photosynthetic. (Beatty et al, PNAS 102:9306 2005). The best argument for life independant of the sun comes from bugs found in isolated waters in South African gold mines, which manage to live on hydrogen produced by radioactivity. It has not been shown, though it is believed to be the case, that they fix their own carbon so we do not know whether they are independent or not. 205.214.48.251 (talk) 20:00, 28 October 2008 (UTC)

While they are obligately photosynthetic they do not get their light from the sun. While the question did not specifically mention the sun I suspect that type of photosynthesis is what they had in mind. Also the vent community is unlikely to rely on the photosynthetic bacteria even though they do exist there. The pertinent question here is not if carbon from the top can enter the system, clearly it can, but is the system sustainable with zero energy and carbon input from above. I believe it is from what i have read. David D. (Talk) 07:06, 29 October 2008 (UTC)

Photosynthesis is when a plant uses the light energy from the sun to help make a sugar in order for the plant to live. —Preceding unsigned comment added by 71.167.96.243 (talk) 01:34, 20 November 2008 (UTC)

Introduction picture?

Now don't get me wrong, a picture of a leaf is great, but wouldn't the diagram of the whole process of help people better understand the whole process of photosynthesis better than a picture of a leaf? 98.166.139.216 (talk) 22:48, 25 November 2008 (UTC)

There is a picture of the whole process in the overview section. I think the picture fits better in that place. {Kasper90 (talk) 08:46, 4 January 2009 (UTC)}

Thanks for actually responding Kasper90 . Your efforts to communicate with anonymous editors like me are greatly appreciated. 98.166.139.216 (talk) 22:00, 12 January 2009 (UTC)

Since there are several possible pathways, what about the primary productivity picture? Tim Vickers (talk) 22:23, 12 January 2009 (UTC)

Algae/bacteria

" It is a complex process occurring in plants, algae, as well as bacteria such as cyanobacteria. " I think it should be: "occuring in plants and algae, like cyanobacteria" Because cyanobacteria are algae, right? or am I wrong? Kasper90 (talk) 13:39, 7 January 2009 (UTC)

Cyanobacteria are a group of bacteria, algae are a poorly-defined group of eukaryotes (protists). Tim Vickers (talk) 17:11, 7 January 2009 (UTC)

Jeah, I just read it.

"Though the prokaryotic Cyanobacteria (commonly referred to as Blue-green Algae) were traditionally included as "Algae" in older textbooks, many modern sources regard this as outdated[4] and restrict the term Algae to eukaryotic organisms.[5]"
I think the dutch algae article is outdated then. Kasper90 (talk) 03:26, 8 January 2009 (UTC)

Quantum section

Moved to talk, seems to have too much text relative to the rest - might be summarised in a sentence later. Tim Vickers (talk) 22:25, 11 January 2009 (UTC)

Quantum mechanical effects

Through photosynthesis, sunlight energy is transferred to molecular reaction centers for conversion into chemical energy with nearly 100-percent efficiency. The transfer of the solar energy takes place almost instantaneously, thus little energy is wasted as heat. Of the total incident solar radiation only 43% can be used (only light in the range 400-700 nm), 80% of light makes it through the canopy, photosynthesis stores 28.6% of the energy, and plant respiration uses some energy which leaves 67% of the stored energy behind. This brings the actual efficiency of photosynthesis to about 6.6%.

A study led by researchers with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley suggests that long-lived wavelike electronic quantum coherence plays an important part in this instantaneous transfer of energy by allowing the photosynthetic system to simultaneously try each potential energy pathway and choose the most efficient option.

=

Oxygen is produced in light-dependent reactions

"Oxygen is a waste product of light-independent reactions"

It should be 'light-dependent'.

86.106.193.108 (talk) 22:18, 3 February 2009 (UTC)

Corrected. Thank you. Tim Vickers (talk) 22:27, 3 February 2009 (UTC)

Energy trapped by photosynthesis

Please replace "100 terawatts per year" with just "100 terawatts". The unit "watt" is already an energy rate. I see that the original source mentions 100 TW/year so I'm not sure if we can trust it, but they do also mention incoming solar radiation to be 178,000 TW/year which is correct if you remove the "/year".

Also replace "which is about seven times" with "which is about six times". (100/16 = 6.25).

I would have done the changes myself but this page is semi-protected. —Preceding unsigned comment added by 24.6.174.244 (talk) 21:26, 8 February 2009 (UTC)