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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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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?

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.
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Do fallen leaves produce oxygen?

After a leaf has fallen from a tree, if it is still green and hasn't dried out, is it still converting CO2 into O2 if not put in water? Can anyone find any data showing how long any different ...
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Can plants yield two more molecules of ATP from glycolysis?

Since 2 ATP are used to convert glucose to glyceraldehyde 3-phosphate in glycolysis, can plants bypass this step of ATP investment since they produce glyceraldehyde 3-phosphate directly from the ...
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Why are C4 plants mainly tropical plants?

Why is it that most C4 plants are tropical plants? As far as I am aware the C4 cycle does not prevent water loss; so having it exist in tropical areas does not serve these plants any good other than ...
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If all animals were to die, would all plants die too?

Humans and many other animals are able to breathe because plants produce more oxygen than they need. I was thinking if all animals died all of a sudden, then wouldn't plants die too. Eventually they ...
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The effect of Atrazine on the LDR in Photosynthesis

The herbicide Atrazine causes inhibition within the Qb site in the D1 protein of photosystem 2. Given this information, would Atrazine’s inhibitory effect halt the production of oxygen or ATP first? ...
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Recent research in bioluminescence powering photosynthesis?

In 2013 there was a Chinese study published on "Bioluminescence as a light source for photosynthesis," which is briefly summarized in this Chemistry World article. There was a question on Biology.SE ...
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Photosynthesis Experiment - unexpected temperature results

So for Stage 2 Biology we had to do a photosynthesis practical where we manipulate one variable. Summary of prac method: - 50 geranium plant leaf discs were cut using a hole puncher and placed into ...
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How many photons are used to make one glucose?

This was a question in a test. The options were (1) 8 (2) 16 (3) 24 (4) 48 My answer is 30 which was not in options. Given answer was 48. 12 NADPH 18 ATP for one glucose 12 NADPH and ATP ...
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Could alternatives to Photosynthesis be possible? [closed]

I'm working on a world for stories and games, and I'm trying to figure out some more diverse plantlife. There are areas of the world that won't get enough sunlight for Photosynthesis, so I'm thinking ...
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Does blue light cause stomata to open or close?

In my biology lecture notes, it says that blue light causes stomata to close. But thinking about it logically, since plants absorb a high percentage of blue light compared to light at other ...
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c4 cycle in photosynthesis occurs in monocots or dicots

the biosynthetic portion of the c4 cycle occurs in the bundle sheath cells and i have studies that bundle sheath cells are present only in dicots and not monocots. according to this, the c4 cycle ...
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Can plants suffer from CO2 poisoning?

Is there a point where too much CO2 is bad for a plant? Basically when there is too much CO2 in the air can a plant get sick? Since plants photosynthesize and need CO2 to generate glucose and store ...
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Oxygen balence from growing plants for food

I had thought photosynthesis and respiration where pretty much Oxygen and Carbon neutral per calorie. http://news.mit.edu/2014/technical-feasibility-mars-one-1014 If, as the project plans, crops ...
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Effect of the Marcus Theory on Photosynthesis

As far as I know, the Marcus Theory explains the rates of electron transfers in reactions as a function of differences in free energy between the product/reactant's potential well. Furthermore, there ...
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Effect of light spectrum on photosynthesis

It is said that the blue and red fraction of VIBGYOR is mainly used for photosynthesis. Can somebody explain why this is so?
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Purpose of the conversion of 3-PGA to G3P in the calvin cycle?

3-PGA ($\ce{C_6H_7O_7P}$) is converted to G3P ($\ce{C_6H_7O_6P}$) before it is able to be made into glucose, with an expansion of 6 ATP and 6 NADPH. My question is why this process is needed and why ...
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What amount of light energy is required to produce one O2 molecule? How about one molecule of NADPH?

I know that for each O2 molecule, a total of 8 photons are required (4 per photosystem). Would the amount of light energy required be E=hc/wavelength using 680 and 700? Or would the energy from the ...
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At what point in the day do plants start to absorb light for photosynthesis?

My plants sit on a small table in my only window, facing Northwest. They are thriving. They are obviously getting enough indirect light to survive year round. Maybe they have adapted? They have never ...
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As electrons are moving through the ETC, how is ATP produced for the active transport to even happen?

A lot of websites aren't being specific and they are just saying that when electrons move from a high to low energy state during the ETC, "energy" is being released and that energy is used to pump (...
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662 views

During non-cyclic photophosphorylation, how does NADP+ become NADPH?

I know that NADP+ gets reduced to form NADPH, but what exactly is being donated? Is it two individual electrons (from photolysis or the chlorophyll molecules) and a hydrogen ion (proton)? If this is ...
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Can plants photosynthesize all-day?

If a plant was given sunlight even during the night, with appropriate constant intensity during day and night, will the plant be able to maintain health and normally photosynthesize throughout the day?...
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Can combining C3, C4 and CAM plants in a greenhouse/vertical farm increase the efficiency of plant production?

I am reading a little about different types of photosynthetic systems in plants because I want to learn something about plant production in greenhouses/vertical farms (I have no experience in this ...
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Import of H+ ions into the thylakoid space during photosynthesis in plants [closed]

Why are H+ ions pumped into the thylakoid space as the electrons pass through the cytochrome complex from PS2 to PS1 during photosynthesis?
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Intermediate of Krebs cycle that can form Chlorophyll?

This was a question in a test in my school today. Q) Which intermediate of Krebs cycle further can form chlorophyll? A) Oxaloacetic acid B) Citric acid C) Succinyl CoA D) Fumarate Given answer was ...
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Potato Power. Self sustaining medium using a living potato plant possible?

The second picture are potatoes wired in parallel. I understand that the potato is the medium for a chemical reaction between the copper and zinc. That aside, would wired and in soil potato plant ...
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Chloroplasts in an animal cell

What would happen if we inject a chloroplast organelle into an animal cell? Will the animal cell destroy it? Or is it possible that the chloroplast will somehow survive, and even replicate? Could ...
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Cyanobacteria pools as carbon sinks

According to some scientists, at one point in time in this planet's history cyanobacteria almost drove life to extinction by reducing it to a snowball as they captured vast quantities of carbon and ...