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

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Is there nothing such as NADPH2? [duplicate]

I have gone through various sites and some say there is NADPH2 and some say there is no NADPH2 there's only NADP+ ...WHich is the correct view....Please dont mark this answer as duplicates since I ...
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What did cyanobacteria gain from photosynthesis?

As far as I understand, cyanobacteria began performing photosynthesis long before plant cells as we know them arrived on the scene. But cyanobacteria do not seem to use polysaccharides in the same way ...
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55 views

Light and Dark Reaction of photosynthesis?

I'm having a hard time understanding light and dark reactions because all the sites I've gone through provide different equations. Some say photolysis is H20 = H+ + O2 while some present it as H20 = ...
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Why upper surface of leaves is more green and shiny than the lower one?

I have properly googled this and got various answers. However, those answers do not provide an answer to the "Why" part of my question. Why is it that the upper surface of leaves is more green than ...
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Can photosynthesis take place if the plant is kept in ice cold water or not?

Can photosynthesis take place in a plant even if the plant is kept in ice cold water? I have googled this question, but so far have not found a satisfactory answer.
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In flowering plants food is transported in which form? [on hold]

In flowering plants food is transported in which form? I searched on google and found that it is sucrose. Why not glucose/fructose/starch?
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999 views

Why is chlorophyll green? Isn't there a more energetically favorable color? [duplicate]

Chlorophyll being green means it absorbs light in the red and blue area of the spectrum. Isn't this the high and low energy light? Wouldn't plants get more energy if they absorbed light in the green ...
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45 views

Behavior of plant guard cells: open or closed stomata

On an exam of mine, I had the following question: The interaction between the guard cells and stomata in a plant leaf can be seen in the diagram below. In which scenario could the guard ...
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How are ions 'pumped' across a membrane during electron transport?

A number of sites (including this one) that provide descriptions of photosynthesis state that high energy electrons 'pump' ions across a membrane. What is the actual 'pumping' mechanism? I've looked ...
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A question regarding rate of photosynthesis increases [duplicate]

If we keep on increasing CO2 concentration in atmosphere, will the rate of photosynthesis increases or not?
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How are 6 “fixed” CO2 molecules joined toegther as glucose?

When we study calvin cycle, we study it with 6 molecules so as to form 1 glucose in a single cycle as: 6 RuBP + 6 CO2 => 12 3-PGAL => 1 Glucose + 6 RuMP But if we look deep, then we know that the ...
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Why it seems that principles of chemistry are not being applied in this biochemical process? [closed]

According to an answer in this question, my concept used below does not apply: In the non-cyclic photophosphorylation, consider splitting of two water molecules, then 4 e- (electrons) and 4 H+ ...
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How can I estimate the CO₂ uptake of a plant?

I would like to make an estimation of the CO2 uptake of plants I cultivate, including, lettuce and aromatic herbs, such as thyme, basil, rosemary. What I want is to end up with a rough indicator for ...
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About photosynthesis VS respiration [closed]

Is it true to say that the electron transport chain in photosynthesis and respiration is slightly different, regarding to the direction of H+ pumping and flowing back in through ATP synthase? ...
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206 views

Why is ATP produced in photosynthesis used to synthesize glucose?

In photosynthesis ATP is produced in light-dependent reactions only to go to the Calvin cycle to be turned into glucose to make ATP during respiration: Why isn't this ATP just directly released ...
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113 views

How do CAM plants keep stomata closed by day and open at night?

I understand how plants open stomata, with the H+ ion removal and the resulting K+ ion influx in the guard cells to induce turgor (wikipedia article here), though not how this process relates to ...
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272 views

How many ATP are formed?

What is the number of ATP molecules formed during the photosynthetic processes which consume 8 molecules of $\text{H}_2\text{O}$ due to noncyclic electron transport and subsequent ...
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About electrons returning to photosystem I when supply of NADP runs out in photosynthesis

According to my textbook, in photosynthesis, when the supply of NADP runs out, electrons from photosystem I return to the electron transport chain that links the 2 photosystems and flow back to ...
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Can you grow more Biomass in a brickhouse only powered by solar cells than in a greenhouse? Will we ever be able to?

So I asked following question some physicists but they couldn't really help me though: Right now I read that 1m² of solar cells generates roughly 100Watts of energy. There are really efficient ...
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Primary Productivity of Oceans

80% of the world's photosynthesis takes place in the ocean. Despite this, oceans are also said to have low productivity - they cover 75% of the earth's surface, but out of the annual 170 billion ...
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By what mechanism is NADP+ converted to NADPH in Photosystem I? [closed]

Here is my current understanding: $\mathrm{NADP^{+}}$ takes 2 electrons from Ferredoxin at the end of the electron transport chain to generate $\mathrm{NADP^{-}}$. An $\mathrm{H^{+}}$ ion in the ...
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17 views

Lighting device efficacy for plant growth

Background Consider the following technologies: 100 lm/W OLED (2008, source) 303 lm/W LED (2014, source) 94 lm/W LEP (2015, source) For growing food, the preferred measurement is ...
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427 views

Where is energy stored in a molecule of ATP? [closed]

Where is energy stored in a molecule of ATP? How is energy released from a molecule of ATP? What specific bond needs to break What is the difference between ATP and ADP? Define pigment a. What ...
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51 views

Chemosynthesis in Bacteria

The light reactions, if seen as a whole, are basically the oxidation of water to provide energy (ATP) to fuel the Calvin Cycle. The photons provide the activation energy for the same. How then can ...
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Does the location of the double bond in chlorins yield a distinct biological function?

Chlorins differ by the number of double bonds and their location. Chlorin has 20 pi electrons, whereas bacteriochlorin and isobacterichlorin have 18 pi electrons, but at different locations. Do ...
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Trouble understanding how uncouplers in the thylakoid membrane increase the rates of the Electron transport chain?

I am a undergrad in a cell physiology class and just did a learning exercise involving testing rates of the electron transport chain via the reduction of DCPIP, analyzed by spectrophotometry. ( I ...
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Is there a plant particularly suitable for absorbing Hydrogen Sulfide

I live in an area with some open sewers and in the morning I can usually can smell the gas inside my house. There are many plants like snake plant which improve indoor air quality but I was ...
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Experiment to show that carbon dioxide is needed for photosynthesis

In my school test, the question is as follows: Will the experiment work satisfactorily? What alterations can you make to obtain expected result? What I wrote: Yes, it will work satisfactorily. ...
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66 views

pH concentrations during photosynthesis

I'm studying for an AP Bio exam and had the following question: Which of the following parts of an illuminated plant cell would you expect to have the lowest pH? (A) Stroma (B) Cytosol ...
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65 views

Photosynthesis Equation

The equation for photosynthesis is $\ce{6CO2 + 6H2O + Energy -> C6H12O6 + 6O2}$ My confusion rests in the following: during the photolysis (water-splitting) step of the light reactions that ...
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160 views

Can electricity be harvested from the soil around plants? [closed]

This is a rehash of a question I originally wrote on Skeptics which got moved to Physics, but I'm really after an answer from a biological perspective. A device called the E-Kaia is making news by ...
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70 views

What happens to H+ when Glycerate 3-Phosphate is converted to Triose Phosphate?

The conversion from Glycerate 3-Phosphate to Triose Phosphate requires: $ATP \rightarrow ADP + P_i$ $NADPH \rightarrow NADP + H^+$ So what happens to the $H^+$? Is it in-effect "recycled" back to ...
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99 views

What do the numbers in Photosystem I P700 and Photosystem II P680 stand for? Is it the optimum wavelenght? The maximum wavelenght?

I am a bit confused about this because my teacher and english Wikipedia say it's the wavelenght the Photosystem is most reactive to; my textbook and the german Wikipedia say that it is the maximum ...
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How long can a plant generate oxygen from its own carbon dioxide, produced during nighttime?

I recently bought one of these miracle fruit plants (Synsepalum dulcificum). Since they are of tropic origin, they need higher humidity and temperature as we have it here in Austria. So I decided to ...
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63 views

How to calculate PAR and aPAR from reflected + incoming radiance

i have measured the reflected radiance of a plant and the incoming radiance with a point spectrometer from 300 to 700 nm in 1nm increments. How can i calculate photosynthetically active radiation ...
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48 views

The definition of leaf area index

In many textbooks, leaf area index (LAI) is defined as the total leaf area per unit ground area. I want to know LAI is defined only by leaves that are directly above the ground (e.g., perpendicular ...
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How does a garlic clove thrive inside a closed refrigerator?

A garlic clove has been growing very well inside a closed refrigerator. It has developed beautiful green stalks, which I think are the equivalent of leafs. Since they are green, I assume they ...
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What is the use of crystallized Photosystems from cyanobacteria?

I read a lot of articles about techniques for the crystallization of Photosystem I and II from cyanobacteria. My question is what is the reason for that and what can you do with Photosystem crystals?
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Photosynthetic efficiency and light harvesting efficiency

Is there some sort of measure of the light harvesting efficiency (possibly like transfer time) that is directly related to the photosynthetic efficiency in some sort of equation? Also, how important ...
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Why is there a seeming dichotomy between mobility and photosynthesis?

At least among more complex organisms, I cannot think of any examples of highly mobile species (like animals) that also incorporate photosynthesis. Perhaps there are examples that I'm unaware of, but ...
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Synthetic carbon fixation pathways

Have there been carbon fixation pathways of, in particular, oxygen-producing bacteria, that have been replicated in the lab or at least the enzymes for the pathways have been successfully produced in ...
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211 views

Where do the H+ ions come from in light reactions?

In the light-dependent reactions of photosynthesis, H+ ions pass to the thylakoid space. Where do these protons come from?
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Why oceans are carbon sinks?

Building on this question, I understand pretty clearly why forests are carbon sinks (trees grow, and there is carbon stored in soil and biomass). What about the oceans, though? Are underwater ...
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Are trees the only source of large amounts of oxygen?

Trees use carbon dioxide and produce oxygen in the presence of sunlight. But is there any other source? If yes, are trees the most important source of oxygen, or is there any other source which ...
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Can photosyntetic cells be genetically modified to grow at a faster rate?

I hope the question is not silly, but I wonder if a sort of genetically modified plant "cancer" could be used for carbon sequestration. For example, cancer cells like HeLa have been reproduced in ...
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63 views

Where is ATP used in Phosphorylation?

In the section describing the Calvin Cycle, under the subheading "Reduction", my textbook states that: The steps involve utilisation of 2 molecules of ATP for Phosphorylation... I could not get ...
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Do plants with non-green leaves have chlorophyll and photosynthesis?

Is it even possible that plants with non-green leaves have chlorophyll, and do such non-green leaved plants carry out photosynthesis?
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How exactly is glyceraldehyde 3-Phosphate reverted to ribulose 1,5-bisphosphate for the continuation of the calvin cycle?

Around 6 molecules of G3P is produced at the end of the Calvin Cycle (light independent reactions of photosynthesis), and 5 of which are reverted back to RuBp. The general equation that I read is 5 ...
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How does CO₂ concentration affect photosynthesis?

I have heard the theory that with the increase of CO2 in the air, the speed of the photosynthesis would increase, thereby limiting the increase of CO2 levels. What is currently the rate limiting ...
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Are more molecules of ADP than inorganic phosphate returned to the light reaction in photosynthesis?

During the dark reaction, 9 molecules of ATP are consumed for every 3 carbon dioxide molecules, yet only 6 molecules of inorganic phosphate ultimately leave the cycle. Does that mean that there is a ...