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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Why does photosynthesis specifically produce glucose?

Why not a pentose? Or a tetrose? Or a deoxy sugar? Or just some other hexose, like fructose? Is there some chemical reason life should have settled on glucose as the standard photosynthetic output, or ...
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Photolysis of water

Photolysis of water releases $\text{O}_2$, $\text{H}^+$ ions and $\text{e}^-$. $\text{Mn}$ in the $\text{O}_2$ evolving complex also produces $\text{e}^-$. What provides $\text{e}^-$ to P680:$\text{Mn}...
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Do photosynthesis and respiration violate the law of conservation of energy?

I don't know, if it's a physics question, biology or chemistry question but anyways here it is: I have been taught that to produce one molecule of glucose in photosynthesis, 18 ATP molecules are used ...
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How can this coral survive with little sunlight?

Forgive me if this question is off topic, but I’ve seen similar questions so I think it should be on topic. I’m at the beach currently, and I was looking in tide pools for interesting things. I found ...
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Production of “Green Hydrogen” by photosynthesis

In a popular science book from the 1970s I read about experiments to tweak some microorganisms to produce elemental hydrogen by photosynthesis. Is this a feasible way to produce “Green hydrogen”? What ...
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Is plastoquinone not an electron carrier?

In my book, under the topic chemiosmotic hypothesis, it is given that proton gradient is created by accumulation of protons in the lumen of thylakoids. One of the ways by which the gradient is created ...
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How much sunlight is required for photosynthesis to peak?

I've read that photosynthesis peaks at some point over light intensities https://en.wikipedia.org/wiki/PI_curve According to https://www.bbc.co.uk/bitesize/guides/z9pjrwx/revision/5 suggests At very ...
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Does the biofilm formation hinder photosythesis?

In photosynthetic bacteria such as Cyanobacteria, Synechocystis sp. PCC 6803. The bacteria need access to both light, CO2, and water to perform photosynthesis. However, in thick biofilm structures (e....
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How much air does a square meter of sugar beet consume per hour?

I've come across a person who tried to disprove photosynthesis (yeah, I know). The basically took numbers of record sugar beet crop in Chile (192 tonnes per hectare), and tried to calculate how much ...
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Can I use the Winkler method as a way to measure the rate of photosynthesis?

I want to make an investigation where I measure how the color of light affects the rate of photosynthesis. The idea is to put an Elodea plant in a test tube and shine with different color of light ...
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How should I measure the oxygen dispersed during photosynthesis in pondweeds?

I am to conduct a lab investigating how different wavelengths of light affects photosynthesis in Egeria pondweeds. The idea is to put color filters on light bulbs and shine them on the pondweed in a ...
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Chemiosmotic hypothesis [closed]

During the transport of electrons, some H+ are removed from the chloroplast stroma, which causes a proton gradient to build up inside the thylakoid lumen. But what's the source of H+ in stroma at the ...
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Why isolated chlorophyl emits red light?

If we observe isolated chlorophyl solution with UV light, chlorophyl is seen as red. explanation suggests that when specific atom of chlorophyl absorbs UV light, atom gets excited and in a short time ...
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Why are 6 turns of the Calvin cycle needed to make one molecule of glucose?

I‘ve read that 6 turns of the Calvin cycle are required to make 1 glucose molecule. But, 3CO2 and 3RuBP are used in one cycle and 6 triose phosphate is produced. Only 5 triose phosphate molecules are ...
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The reason behind red drop effect

I was reading about Emersion effect on Wikepedia, I was not able to correlate our current knowledge of photosynthesis with this effect, First red drop effect When Emerson exposed green plants to ...
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which carbohydrates are produced in the Calvin Cycle?

I understand the structure of simple carbohydrates (di- and monosaccharides, etc.,) but I'm encountering inconsistent/confusing nomenclature while trying to understand the Calvin Cycle. One source ...
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In the Kok cycle occurring in Photosystem II's Oxygen-evolving Complex, what exactly does P680 do?

I've been reading up on the oxygen-evolving complex using a few sources, but am a non-biology major so my understanding might be somewhat/very flawed. I've been using this source mainly: https://...
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Cyanobacteria and the ratio of Iron to Phosphorous

In listening to a recorded lecture that touched on the Great Oxidation Event, a casual remark was made to the effect that the shifting of the Earth's constituents to more availability of phosphorous ...
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Blooming at moonlight

At the moment a popular question in the physics SE community is about night-blooming cereus: this flower blooms at full moon, that is it is capable of making difference between the moonlight and ...
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Amount of carbon captured in photosynthesis by a plant

Is it more proportional to the mass or the volume of the plant? I thought it might be helpful to think on the cellular level here. Even a reference to an external explanation would be useful.
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What genes are required to make E. coli photosynthetic?

"All" of the genes for bacterial photosynthesis were discovered in a gene cluster almost 40 years ago. Marrs, J.Bact. What more is needed to make E. coli photosynthetic?
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CAM Photosynthesis Oxygen Generation?

I've been looking into CAM plants - notably the snake plant which is native to West Africa. Upon researching the CAM photosynthesis cycle, I've found it fascinating that the plant stores CO2 at night ...
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Structure and reactions of the cofactors of oxidoreductases such as ferredoxin

I have seen the word flavoprotein being used in place of ferredoxin in few places and vice-versa. I have not found any source that mentions them both together and explains the relation between them. ...
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Calvin cycle- combining three "turns"

In the common Calvin cycle diagram, it is commonly stated that "three cycles are combined to show the production of 1 molecule of G3P". How does the G3P molecule escape from this cycle in ...
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Is there a known efficiency rate for CO2 capture from ambient air in photosynthesising plants?

When humans take in air to their lungs, we capture about 5% of the total quantity of the air as oxygen (which in turn equals about 24% of the available oxygen in the air) Is there an equivalent rate ...
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Light intensity effect on plant transpiration

In the graph of light intensity versus rate of transpiration, the rate increases up to a certain point but then remains constant. What is the reason that it stays constant, is there a limiting factor ...
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How do the High-Energy Electrons During Chemiosmosis Come from Water?

On Pg. 199 of Campbell, this is stated. Both* work by way of chemiosmosis, but in chloro- plasts, the high-energy electrons dropped down the transport chain come from water, while in mitochondria, ...
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5 votes
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How come only a handful of animals can do photosynthesis?

As far as I understand, all the energy that living beings rely on comes from the sun. It's processed by plants in photosynthesis. These plants are consumed by herbivores, which in turn are consumed by ...
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Do fish depend on plants for survival?

As far as I know, all land life depends on plants for survival. Plants convert sunlight to energy using photosynthesis, herbivores consume plants, and carnivores consume herbivores. All the energy is ...
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Why doesn't the rate of photosynthesis increase with increasing light energy (frequency)? [duplicate]

Why doesn't the rate of photosynthesis increase with increasing light energy (frequency)? I know that green light is not absorbed by chlorophyll, yet I am confused as to why this certain "...
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6 votes
2 answers
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How many times did photosynthesis evolve?

Was it a 1 and done thing? Plants seem to have developed photosynthesis by the endosymbiosis of cyanobacteria. Is the latter the one time in Earth's history that the process independently came about? ...
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Can we achieve complete photosynthesis on a petri dish? Barriers and potential

If we were to place bacteriorhodopsin and ATP synthase in an acidified solution (for H+ ions) filled with phospholipids, ADP and inorganic phosphate, hopefully the bacteriorhodopsin and ATP synthase ...
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Are there any fluorescent proteins capable of transforming 500-600 nm light to 400-500 or 600-700 nm?

In order to improve photosynthesis, which doesn't use 500-600 nm light, I wonder if that light can be transformed into useful light? The idea is to transfect photosynthesis organisms with the gene for ...
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4 votes
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What part, roughly, of the carbon in a plant comes from the soil? As opposed to the atmosphere?

C4 plants contain a slightly higher percentage of carbon-13 than C3 plants. Is this because of carbon obtained from the soil or the atmosphere? I have read that plants using different chemical ...
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Can we produce sugar using chlorophyll dissolved in ethanol?

I can't find anything about this on the net. I read in my (high-school) textbook that if plants get sunlight, water and carbon dioxide, and the catalyst called chlorophyll, they can make sugar. I'm ...
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Is this question about limiting factors answerable?

This is from a Singapore-Cambridge GCE O-level Biology exam (a national exam for 16-year-olds). The exam board maintains that the question is "correct and accurate"—but isn't there a typo in ...
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How does the light-independent stage of photosynthesis get H+ ions?

From what I understand from my grade 11 biology: During the light-dependent stage of photosynthesis, water molecules split, producing hydrogen and oxygen atoms. The oxygen atoms are basically “waste ...
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3 votes
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How is Elysia chlorotica classified as an animal capable of photosynthesis?

Elysia chlorotica is a kind of sea slug. Technically, it's an animal. However, it undergoes a process called kleptoplasty, which is the absorption of chloroplasts from algal prey cells which are then ...
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2 votes
1 answer
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How quickly are plants able to sense changes in light intensity?

Evidently due to the process of photosynthesis, plants are able to "sense" light (as demonstrated by the phototropic response). My question is, how quickly are plants able to perceive ...
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Is there such a thing as an autotroph that doesn't use photosynthesis?

I've heard of photoautotrophs, which are just autotrophs that use photosynthesis. What I'm wondering is if there's any other way for an organism to make its own food that doesn't involve it using ...
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Phytomass and photosynthesis

I have been introduced to the term "phytomass" and I was wondering if phytomass can be both photosynthetic and non-photosynthetic?
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1 vote
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Is there any study to find the plant with the absolute minimum light need?

Is there any study to find plants with absolute minimum light need? Consider a bathroom without windows that you have occasional artificial light (e.g. white LED light). Another question is there ...
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Do plants take in the same amount of CO2 as they release?

There are many claims in the media that trees remove more carbon dioxide form the atmosphere than they release back into the atmosphere. By what chemical pathway can this occur? The law that matter is ...
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Do plant cells recycle carbon dioxide from their respiration during photosynthesis? [duplicate]

It seems one of my colleague's biology textbook claims that plant cells, with presence of light, feed back 100% of carbon dioxide molecules from their respiration into photosynthesis. Can you say that ...
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Why do quaking aspens quake?

I've just finished reading The Hidden Lives of Trees by Peter Wohlleben, which I thoroughly enjoyed. According to the author, the advantage of shaking the leaves is that both sides of the leaf are ...
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Does photosynthesis begin instantly when a plant is exposed to light?

I'm curious to know if the process of photosynthesis has a "ramp-up" time to become useful to a plant, or if it begins instantaneously when the plant is exposed to light after a period of darkness. ...
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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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1 vote
1 answer
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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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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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