46 votes

Does any organism use both photosynthesis and respiration?

tl;dr: Yes, all plants breathe.— I'm not sure whether I understand the question correctly; because all plants use respiration! Some of the organic high-energy substances produced by ...
45 votes
Accepted

Why "Having chlorophyll without photosynthesis is actually very dangerous" and "like living with a bomb"?

Chlorophyll absorbs photons (light). The energy in the photon extracts an electron from a molecule of water. Electron transfer creates intermediate superoxide and hydroxyl radicals from the oxygen and ...
41 votes
Accepted

Do photosynthesis and respiration violate the law of conservation of energy?

With slight adjustments to the scientific wording, what the poster states is in effect: “…to produce one molecule of glucose in photosynthesis, 18 ATP molecules are used up hydrolysed” and “…...
  • 22.6k
40 votes
Accepted

Are trees the only source of large amounts of oxygen?

71% of the earth's surface is taken up by water. Not surprisingly therefore, the seas are an important source of oxygen. National Geographic claims that photosynthesis by phytoplankton (mostly single-...
  • 51.5k
29 votes
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Can plants suffer from CO2 poisoning?

Short answer It has been shown that plants may already suffer from doubling the atmospheric CO2 concentration from 340 to 610 ppm, something that might happen during the next hundred years or so based ...
  • 51.5k
20 votes

Do electromagnetic waves outside the visible spectrum have any role in photosynthesis?

Photosynthesis is nearly all visible light. There's usually not enough UV and thermodynamics more or less rules out infrared. Chris covered that pretty spectacularly, but that nearly is significant. ...
  • 3,988
20 votes
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Is agriculture really a net contributor of greenhouse gases?

The issue is that it is not always a cycle, when you drain wetlands or burn forests to make more farmland that's not a cycle that is permanent change. A change that can continue having effects for ...
  • 13.3k
18 votes

Why do plants have green leaves and not red?

I know this question was asked and answered a number of years ago (with many great answers), but I couldn't help but notice that no one had approached this from an evolutionary perspective (like the ...
17 votes

Can plants suffer from CO2 poisoning?

It depends upon the plant species. As explained in Algae thrive under Pure CO2 Nature 227, pages 744–745 (15 August 1970): Cyanidium caldarium (an algae found in Yellowstone National Park) ...
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16 votes
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Do electromagnetic waves outside the visible spectrum have any role in photosynthesis?

Photosynthesis only occurs in the visible light.have a look at the absorption spectra of the different pigments involved in photosynthesis, you see that all these pigments absorb light between 400 and ...
  • 49.4k
16 votes

Chorophyll and photosynthesis in plants with coloured leaves

Most of ornamental (often variegated ) plants do performs photosynthesis. They do have chlorophyll even if their color is not green. They have non-green color due to various different pigments. These ...
  • 2,396
15 votes

Why does the oxygen produced in the photosynthesis come from water and not carbon dioxide?

Photosynthesis uses chlorophyll (or other pigments) for harnessing photons and water (or other compounds) as electron donor $H_2O = 1/2O_2 + 2H^+ + 2e^-$. After splitting the water it sends the ...
  • 4,450
15 votes
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Does any organism use both photosynthesis and respiration?

Besides the unicellular organisms cited by other answers (and the fact that plants actually do respiration), there are some animals who are able to get, although indirectly, energy from photosynthesis ...
15 votes

Why does photosynthesis specifically produce glucose?

Glucose is such a ubiquitous energy storage molecule, that we show the simple photosynthetic chemical equation to include the capture of six CO2 molecules to create one glucose molecule. However, the ...
  • 1,731
14 votes
Accepted

Why is ATP produced in photosynthesis used to synthesize glucose?

As far as I can understand your question, you wish to know why a plant cell consumes ATP to produce glucose when it can directly use the ATP as an energy molecule. ATP is an energy currency and is ...
  • 35.1k
14 votes
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Can plants produce oxygen at night (without light)?

Short Answer: Any plant can produce oxygen at night, but plants cannot produce oxygen without light. Longer Answer: It all comes down to spontaneity of a reaction i.e. whether a reaction can occur ...
13 votes

Are two colors (red + blue) necessary for LED grow lights, or would either color be sufficient?

tl;dr: Sort of? Logically, either red or blue light should be sufficient. Chlorophyll a and chlorophyll b preferentially activate different photosystems, and both photosystems are required in green ...
  • 3,988
12 votes
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Can plants grow under extreme (>1%) carbon dioxide concentrations?

Yes they can, but their normal growth is somewhat impaired. A study by Bugbee and collaborators showed that while the yield of rice and wheat increases with CO2 up to about 0.1% CO2, yield decreases ...
  • 3,751
12 votes
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Is it considered feasible to genetically improve plants for better Carbon dioxide breakdown?

I'm not sure from your question if you're clear on the relationship between carbon fixation and 'energy', so just to be clear: carbon fixation in photosynthesis is the process of capturing CO2 and ...
  • 3,348
12 votes
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Why aren't leaves black?

Evolutionary answer: I like to go one step before green plants and consider the humble alga. Algae were historically classified as green, red, and brown, based on the wavelengths that their ...
11 votes

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

The reason that chlorophyll is green is because it absorbs other colors of light such as red and blue, so in a way the green light is reflected out since the pigment does not absorb it. Because life ...
  • 2,573
10 votes

Why does the oxygen produced in the photosynthesis come from water and not carbon dioxide?

It’s not about the oxygen! This question indicates two misplaced concerns. One is with oxygen. I imagine that this is because of its importance to us as animals; however as far as photosynthesis is ...
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10 votes
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What is the relationship between the light and dark reactions of photosynthesis?

ATP is a bad medium for storing energy as detailed here. ATP has a molecular weight of 507 Da Glucose has a molecular weight of 180 Da, and contains the same amount of energy as 31 ATP ...
  • 2,504
9 votes
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Do plants with non-green leaves have chlorophyll and photosynthesis?

Yes, it is possible, but not necessarily the case. Non-green leaves with chlorophyl: There are leaves that don't appear green, but do have chlorophyl and therefore can conduct photosynthesis. (See, ...
  • 5,809
9 votes

Are trees the only source of large amounts of oxygen?

I am not sure which class of organisms have the highest contribution in oxygen production but diatoms do have a significant contribution. The introduction in this paper says that diatoms account for ...
  • 35.1k
9 votes
Accepted

The colour of aquatic plants found deep under oceans

You're right that certain wavelengths of light are more capable of penetrating deeper depths of water. However, it turns out, blue light typically travels to deeper depths than all other visible ...
8 votes

Why are there no known photosynthetic archaea?

There are photosynthetic archaea (such as Halobacterium) but the mechanism is different. They use rhodopsin-like ion pumps (bacteriorhodopsin and halorhodopsin) to move ions against the gradient and ...
  • 35.1k
8 votes

Why are C4 plants mainly tropical plants?

This is not my field, so the following is based solely on a brief reading of Internet sources. The Wikipedia entry on C4 carbon fixation states: When grown in the same environment, at 30°C, C3 ...
  • 22.6k
8 votes

Do fish depend on plants for survival?

Yes, photosynthesis provides nearly all of the ocean's biomass and energy. The best is to study oceanic food chains and webs. It looks like there aren't enough plants in the ocean because they don't ...

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