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Questions tagged [photosynthesis]

The process by which light energy is harnessed to assemble organic compounds (esp. glucose) from inorganic carbon dioxide.

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Nitrogen deficiency and chloroplast function

Q. The formation of which of the following in the chloroplast is affected by a deficiency in nitrogen? (a) Glyceraldehyde 3-phosphate (b) Starch (c) Enzymes (d) Carbohydrates My thoughts: Nitrogen ...
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Could Cyanobacteria farms help dilute pollutants in the atmosphere

If I understand correctly, roughly ~2.8 billion years ago cyanobacteria started pumping large amounts of oxygen into the atmosphere. Using modern industrial processes could this be emulated by ...
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Emerson's 2nd effect/ Emerson's enhancement effect and evidence of existence of 2 photosystems

(https://i.stack.imgur.com/Qbai6.jpg) https://en.m.wikipedia.org/wiki/Emerson_effect I can't understand why is there a need of 2 photosystems (precisely-2 interconnected pigment systems) to explain ...
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Do plants refix some of the carbon dioxide in the Calvin cycle that they produce through cellular respiration?

Plants do cellular respiration and release CO2 into the air, but does the plant also use some of this CO2 to do the Calvin cycle? Or does all the CO2 required for the Calvin cycle come in through the ...
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What is the best method for measuring photorespiration?

I want to know how to discriminate between the oxygenation and carboxylation activities of RUBISCO.
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Photolysis in the Light Reactions of Photosynthesis [duplicate]

I'm a bit confused concerning photolysis. During the light reactions, photons are used to excite the chlorophyll molecules so they are passed to the primary electron acceptor. The electrons initially ...
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Why does atrazine kill photosynthetic bacteria and not nonphotosynthetic bacteria?

Atrazine was found to bind to Qb, which is involved in electron transport to create ATP in photosynthetic bacteria. Why does this herbicide kill photosynthetic bacteria, while having little to no ...
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Plant respiration produces carbon dioxide, so why are plants regarded as decreasing its atmospheric concentration?

In the absence of sunlight, plants give out the greenhouse gas, carbon dioxide. So why is it said that plants increase the concentration of atmospheric oxygen? Do they not increase the concentration ...
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Why do plants do Photosynthesis and then Aerobic Respiration? [duplicate]

Plants do Photosynthesis in order to convert sunlight energy into chemical energy. They first store energy in ATP + NADPH and then use those two compounds in order to create Glyceraldehyde 3-phosphate ...
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Effect of light intensity on the frequency of stomata

According to this article, the frequency of stomata increases with an increase in the intensity of light. What I inferred from this is, since the rate of photosynthesis increases at higher light ...
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How is C4 pathway more water efficient than C3 pathway in photosynthesis?

In the C3 pathway: 1 H2O molecule is required for the fixation of 1 CO2 molecule. In the C4 pathway: The only H2O molecule used is in the calvin cycle, so 1 H2O molecule required for fixation of 1 ...
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Photosynthesis production of oxygen [closed]

If you are to increase the intensity of light indefinitely, would you expect the production of oxygen to continue to increase?
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absorption spectrum & photosystems

i've a doubt in biology on photosynthesis and it's super confusing to attempt to solve solo. can someone help me out please? my biology textbook states that photosystem 1 and photosystem 2 has ...
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Photosynthesis immature fruits [duplicate]

Do immature fruits perform photosynthesis? Yes they have chlorophyll bodies. But do they have stomata through which they can absorb carbondioxide like the green leaves? Sincerely Ulrik
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Why have plants evolved to photosynthesize glucose instead of another molecular compound?

I think this question can be broken down into two sub-questions: Why do plants produce $C_6H_{12}O_6$ as opposed to another molecule following the formula of $C_nH_{2n}O_n$? Why not $C_8H_{16}O_8$, $...
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Chorophyll and photosynthesis in plants with coloured leaves

Do plants that have only coloured leaves (e.g. ‘ornamental’ plants) contain chlorophyll and perform photosynthesis? If they don’t, how do they obtain energy and metabolic intermediates?
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How many electrons does the b6-f complex need to pump one proton into the thylakoid lumen?

In photosynthesis, photons are used through photolysis to split water molecules and retrieve their hydrogen ions and electrons in the water-splitting complex. For each four photons, two water ...
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what is the integral of PAR radiation over total solar radiation

This paper say 48%: What is the maximum efficiency with which photosynthesis can convert solar energy into biomass? -Zhu 2008 Also why does Zhu use 740 nm at high end of PAR wavelength! My ...
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Which complexes physically pump protons in photosynthesis?

The cytochrome b6f complex is often drawn as pumping protons, but then someone told me that actually there is no pumping, rather the Q cycle. According to this view, what actually moves the protons ...
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How does the emerson effect produce a higher rate of photosynthesis?

Can anyone explain how the emerson effect works to increase the rate of photosynthesis, and as the original studies were done over 50 years ago, how much research is still done into this area? Or is ...
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Is coral photosynthesis dependant on the wavelength or frequency of light?

When buying a light fixture for a marine fish tank, it is often sold with some technical data reguarding the spectral output of the light, with a peak in the blue region of visible light, somewhere ...
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Why “Having chlorophyll without photosynthesis is actually very dangerous” and “like living with a bomb”?

The Phys.org article Scientists discover first organism with chlorophyll genes that doesn't photosynthesize says "For the first time scientists have found an organism that can produce chlorophyll ...
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Photosynthesis: Can light directly excite the reaction center instead of going through the antenna complex?

The reaction centers that I am interested in are P680(photosystem II) and P700 (photosystem I) Here is what I think: If pigments such as chlorophyll a and b capture light in the antenna complex, and ...
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Fuel from photosynthesis

I was reading how plants make use of sunlight, CO2 and some other stuff to make energy. So why can't we create artificially engineered bio solar panels which will take sunlight, C02, water and other ...
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Winter is getting shorter and warmer. Does this mean deciduous trees can photosynthesise for longer and thus absorb more carbon dioxide?

As springtime is starting earlier this year, I wondered if that would mean deciduous trees had more time to photosynthesise and, therefore, they could absorb more CO2 or have longer periods to grow, ...
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Calculation of Respiration Fluxes in Terrestrial Ecosystems Based on Total Respiration (RT)

Overview Researchers have been studying a temperate grassland ecosystem with the view to understand it's current status with regard to carbon inputs and outputs and to identify whether the grassland ...
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What does the difference between GPP - NPP represent?

Overview Researchers have been studying a temperate grassland ecosystem with the view to understand it's current status with regard to carbon inputs and outputs and to identify whether the grassland ...
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How much energy takes C4 photosyntesis to make glucose?

Wikipedia has a kind of contradiction that I would like to understand: According to this link The C3 pathway requires 18 ATP for the synthesis of one molecule of glucose while the C4 pathway ...
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Why is photosynthesis described as a “physico-chemical” process? [closed]

In my textbook it is given that photosynthesis is a physico-chemical process. How can it be a physical process?
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In plant photosynthesis, in the light dependent reactions, why is 3 ATP produced per 2 H2O?

I've been looking at the light-dependent reactions on Wikipedia and Khan Academy. This is the net reaction: $$2H_2O + 2NADP^+ + 3ADP + 3P_i \to O_2 + 2NADPH + 3ATP$$ So for every $2H_2O$ I expect $...
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What is the evolutionary relationship between heme, chlorophyll and other tetrapyrroles?

As a non-biologist, I have searched the Internet and found dozens of papers discussing the similarity between the structures of heme and chlorophyll molecules, but I could not find any discussion of ...
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What does the spectrum of Chlorophyll fluorescence look like?

I've just posted the question Which spacecraft can see plants "glow" during photosynthesis during the day, and what wavelength does it use? in a different SE site. I can't remember the details of ...
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What is difference between light harvesting complex , reaction centre and photosystem

my book says light harvesting Complex are made up of hundred of pigment molecule bound to protein. Is photosystem has all the pigment (except one molecule of chlorophyll A )forming light harvesting ...
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How to add oxygen to indoor air without opening windows?

I'm not a biologist. I have read that low oxygen levels in the home can have a negative effect on health. I am interested in increasing the amount of oxygen in the air in my home. To open the windows ...
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Why aren't leaves black?

I s'pose this is a variant of the age-old question, "Why are leaves green?" It's fairly easy to ask teh internets and find plenty of answers for that one. I have a different but related question: ...
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How much plant grow is required for a human's oxygen consumption?

I think Plants do: 6CO2 + 6H2O -> C6H12O + 6O2 I'm thinking that plants take 12 + 6 moles of oxygen and give back 12 mols of breathable oxygen and 1 mol of Cellulose. I've read that a person needs ...
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Are the bacteria doing the same photosynthesis as plants do?

I mean Plants during photosynthesis produce oxygen but Do bacteria also produce oxygen during photosynthesis or produce other gases? If yes , how do these bacteria process photosynthesis by ...
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How does temperature affect photosynthesis?

I am doing a lab for biology and my teacher required me to do this virtual lab. However, it does not make sense when seeing the results of the lab. In 30 second trials, it shows that there are 16 ...
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How do plants take in only carbon dioxide?

There are only 400 molecules of CO2 in 1 million molecules of air. How do plants only take in CO2 but not the other gases? My teacher told me that's because there is less concentration of CO2 in ...
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Could cyanobacteria thrive with very high CO2 concentrations and almost no oxygen to start with?

Has there been research to see if cyanobacteria could live in high levels of CO2, like in the atmosphere of Venus ? Because cyanobacteria caused the Great Oxygenation Event one might expect that they ...
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Can humans eat green leaves to get necessary daily energy intake? [closed]

Green leaves make carbohydrates by photosynthesis. This means that green leaves are abundant source of energy. Can humans eat enough green leaves off the trees and get necessary daily energy intake?
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Are bananas C3, C4, or CAM plants?

Are bananas C3, C4, or CAM plants? I have been researching for some time and cannot find the answer.
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What happens when pure chlorophyll A absorbs blue light?

When pure chlorophyll A is put in the presence of only blue light, what happens? My guess is that the extra energy is released as heat/kinetic energy, and then the electron has dropped to the lowest ...
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Where does NADP+ come from?

Trying to understand Photosynthesis better. I understand the NADP+ is reduced to NADPH in light dependent reactions and NADPH is then recycled back into NADP+ in the Calvin cycle. What I don't ...
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Does an old growth forest ecosystem produce more oxygen than it consumes?

I would like to consider an old growth forest ecosystem such as a large part of the Amazonian forest. It is common to refer to such beautiful forests as a source of oxygen for the world. For example, ...
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What values to be taken for x-axis and y-axis?

I did a lab on form and function in photosynthesis and I recorded the values of absorption spectrum in spinach chlorophyll extract. I have the following data and I need to draw a graph. I didn't ...
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Could higher carbon dioxide levels be beneficial to plants?

C4 plants take ATP-expensive routes to ensure photorespiration does not occur. They minimise oxygen concentration in cells where the Krebs cycle occurs and cart carbon dioxide into these same cells. ...
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Does the sun light have to have *direct access* to fruits to make them sweet?

I understand that sun light is needed for fruits to ripen. In the years with less sun light, the fruits are usually not so sweet. So the sun light is needed to make the fruits sweet. Where and how ...
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Is the rate of photosynthesis higher than the rate of respiration?

In photosynthesis carbon dioxide is used up and oxygen is produced and at the same time plants respire too. So oxygen is used up and carbon dioxide is produced. Then the net exchange of gases should ...
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From where does the oxygen in glucose come in photosynthesis?

Is it carbon dioxide or water? I'm talking about the oxygen present in glucose and not the oxygen that is released after photolysis of water.