47
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 ...
- 5,568
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
“…...
- 24.3k
29
votes
Accepted
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 ...
- 52.3k
20
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 ...
- 29.7k
20
votes
Accepted
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 ...
- 14.3k
18
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
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
Accepted
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 ...
- 346
15
votes
Accepted
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 ...
- 321
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 ...
- 2,298
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 ...
- 35.2k
14
votes
Accepted
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 ...
- 14.1k
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 ...
- 4,028
12
votes
Accepted
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 ...
- 3,346
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 ...
- 2,603
11
votes
What part, roughly, of the carbon in a plant comes from the soil? As opposed to the atmosphere?
Only a small fraction of plant carbon is soil-derived: e.g. from Majlesi et al 2019:
although the majority of plant C was obtained from atmosphere by photosynthesis, a significant portion (up to 3–5%)...
- 5,324
10
votes
Accepted
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 ...
- 2,606
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 ...
- 24.3k
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 ...
- 29.7k
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 ...
- 24.3k
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 ...
- 10.3k
7
votes
What determines the efficiency of electron production in photosynthetic bacteria?
You may or may not consider this an actual answer to your entire question, but it's interesting nonetheless.
A physicist friend of mine did some work recently modelling the quantum dynamics of ...
- 1,301
7
votes
Accepted
Violation of the law of energy conservation between photosynthesis and respiration?
The Fallacies in the argument
The question contains two main fallacies (some would say sleights of hand) in the energetic comparison of glucose synthesis from CO2 in the Calvin cycle and glucose ...
- 24.3k
7
votes
Is it considered feasible to genetically improve plants for better Carbon dioxide breakdown?
Many if not most plants undergo less photosynthesis than they possibly could. This is because water availability is often their major limiting factor. Plants have to keep the tissue they respire ...
- 14.3k
7
votes
Accepted
Do fish depend on plants for survival?
Short answer
All marine life needs energy to survive and reproduce. "Heterotrophic" organisms get their energy from eating other organisms and digesting the molecules of their tissues for ...
- 29.7k
6
votes
Accepted
Quinone A, Quinone B, Ubiquinone, Plastoquinone: whats the difference?
Difference between Ubiquinone (UQ) and Plastoquinone (PQ)
Structural Difference: Structurally, UQ and PQ are very similar. They only differ in a methyl group and 2 substituents on the benzoquinone ...
- 14.1k
6
votes
How much oxygen does a plant use up at night?
Roughly, half of the CO2 assimilated annually through photosynthesis
is released back to the atmosphere by plant respiration (Gifford,
1994; Amthor, 1995).
Source:
https://academic.oup.com/aob/...
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