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

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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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24 views

About photosynthesis VS respiration

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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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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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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Why is ATP converted into 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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All about Sansevieria [closed]

1.Does Sansevieria plant gives out O2 at both day and night ? 2.Is it possible to grow Sansevieria plant with out sunlight ? (If not) 3.How many hours of sunlight is needed per day and what is the ...
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63 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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What part of the cactus photosynthesizes?

In general, plants photosynthesize through their leaves and, to a much lesser extent, through their stems. Cacti, however, have no visible leaves, but instead spines. In what part of the cactus does ...
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15 views

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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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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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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725 views

What types of light can't a plant photosynthesize in?

I have a plant on my desk, and it got me to wondering: Can my plant use the light from my monitors to photosynthesize? If so, what light (apart from green light, to a degree) can't plants use to ...
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63 views

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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1answer
60 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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Does photosynthesis occur on cloudy days or does it require direct sunlight?

In my basic science classes in high school, I have learned that during photosynthesis, plants absorb sunlight and produce food by converting carbon dioxide and water into sugar and starch. To me, ...
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679 views

Photosynthesis: What Powers the Splitting of Water?

The splitting of water is an endergonic (non-spontaneous) reaction, and thus would require energy (chemical work to be done) in order to happen. In Photosystem II, an enzyme catalyzes this splitting, ...
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15 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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1answer
360 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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1answer
38 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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33 views

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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373 views

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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Why does the oxygen produced in the photosynthesis come from water and not CO$_2$?

In the photosynthesis equation $$6*CO_2+6*H_2O+sunlight\rightarrow C_6H_{12}O_6+6*O_2$$ the only place where we have 6 molecules of $O_2$ is in the $6*CO_2$. Then it reacts with $H_2O$ to form ...
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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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45 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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106 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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1answer
72 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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36 views

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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51 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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6answers
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Why do plants have green leaves and not red?

I know plants are green due to chlorophyll. Surely it would be more beneficial for plants to be red than green as by being green they reflect green light and do not absorb it even though green light ...
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35 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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201 views

Organisms using thermal energy as their sole energy source

After seeing this question I remembered that in secondary school we watched a documentary stating something along the lines of "all organisms derive their energy directly or indirectly from the sun. ...
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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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When is Water Produced During Photosynthesis?

The formula for photosynthesis is: $$6CO_2+12H_2O \rightarrow C_6H_{12}O_6+6O_2+6H_2O$$ I can count the carbons, the waters on the reactant side, the oxygens, and the glucose, but I cannot seem to ...
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1answer
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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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Does the light color spectrum and frequency matter for photosynthesis?

Do plants grow differently when given sun light, wolfram lamp, fluorescent light, LED light, infrared, ultraviolet, x-ray, unfocused laser and stroboscope?
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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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62 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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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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Do trees really get a large share of their mass from the carbon in the air?

I remember hearing that trees and other plants actually obtain a large amount of their mass from the carbon floating in the air, not the ground beneath them. Does the makeup of air actually contain ...
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71 views

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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How is photosynthesis observed?

How is photosynthesis observed? Say I have plants A and B, and I want to find how fast they are able to turn carbon dioxide into oxygen. How would I experiment this? Say I have one plant A, 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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611 views

Question regarding Rate of Photosynthesis AP Biology Lab

We are doing a lab on the effects of light intensity/wavelength on the rate of photosynthesis in AP bio and we were asked to visit this website here: ...
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Can we harvest energy from plants?

This is a cross-cutting question but I think its core is about biology. Our society's need for energy is dramatically growing and we are messing up with our environment to answer them. Maybe another ...
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Do electromagnetic waves outside the visible spectrum have any role in photosynthesis?

Does photosynthesis occur only in the visible spectrum? If there is a way to completely remove all other electromagnetic bands from the sunlight, including infrared (IR), will photosynthesis continue ...