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 ...
Peter - Reinstate Monica's user avatar
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 “…...
David's user avatar
  • 25.7k
18 votes
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Is death by cyanide the same as suffocation?

In suffocation or asphyxiation you are actually deprived of breathing oxygen. As a result, the arterial blood oxygen concentration decreases (hypoxemia) which is detected by the chemoreceptors of the ...
deechitpoudel's user avatar
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 ...
Brian Hellekin's user avatar
11 votes

How does the body switch between aerobic and anaerobic respiration?

The simple answer to your question is that in the absence of oxygen the electron transport chain stops. (It can't go backwards, that would generate oxygen.) However your assumption that it stops at ...
David's user avatar
  • 25.7k
11 votes

Why is ATP synthase sometimes referred to as ATPase?

The way we were To understand why you may encounter ATP synthase referred to as ATPase, you need to be aware of the historical context — the experimental work that preceded the knowledge of the ...
David's user avatar
  • 25.7k
9 votes
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What are the sources of molecular hydrogen in human breath?

Hydrogen in breath arises from normal intestinal bacteria, mainly in the colon, which break down (ferment) the undigested nutrients that have passed through the small intestine. Hydrogen is absorbed ...
Jan's user avatar
  • 8,079
9 votes

Are there land animals that use gill-like organs instead of lungs?

Terrestrial crustaceans are land animals that use gills (or gill-like structures) for gas exchange, though these gills must be kept moist for efficient respiration. Specifically, animals like hermit ...
acvill's user avatar
  • 8,296
8 votes

Cough at 1000 km/h?

This reference from CHEST lists 21 clinically measured peak flow rates during various modes of coughing. Of these patients, and for unassisted cough, the highest peak flow is about 4 liters/sec. The ...
docscience's user avatar
8 votes

Is death by cyanide the same as suffocation?

I'm not a doctor, so I'm not 100% sure about the physiological differences, but on a molecular level there is one: Cyanide blocks the complex IV of the oxidative phosphorlytaion, which will directly ...
Nicolai's user avatar
  • 4,391
8 votes

Are there land animals that use gill-like organs instead of lungs?

Some terrestrial hermit crabs (genus Coenobita) have gills, but these are only partially responsible for their respiration1. These animals carry around water with them in the snail shell they 'wear'. ...
tyersome's user avatar
  • 5,598
8 votes

Why does exhaled air still contain oxygen?

You seem to be confused about diffusion versus bulk flow of fluid (air/gas). In the lungs, there is diffusion between blood and the gas in the lungs. There is sufficient surface area that these ...
Bryan Krause's user avatar
  • 45.6k
8 votes

Besides carbon dioxide and water vapor, what waste gases are removed through the human respiratory system?

These sources are understandably couched in their language, but wikipedia is more certain: All the metabolic wastes are excreted in a form of water solutes through the excretory organs (nephridia, ...
Maximilian Press's user avatar
7 votes
Accepted

What is a lethal dose of THC?

According to the abstract from this paper, the intragastric LD50 of $\Delta^9THC$ (tetrahydrocannabinol) in sesame oil using Fischer rats was 1270 mg/kg. Assuming rats and humans are identical (they'...
MattDMo's user avatar
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7 votes
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Why can one swim longer underwater by blowing out air?

This is purely a psychological response, and it does not help in decreasing the speed of CO2 level rise. As CO2 level in your blood rises, you instinctively want to breath out the 'bad' air and breath ...
kubanczyk's user avatar
  • 236
7 votes
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How could cyanobacteria survive the anaerobic conditions of ancient earth?

The first cyanobacteria were probably anaerobic, and this matter seems to be a hot topic of contemporary research. A recently published studya that performed a phylogenetic analysis of various ...
adjan's user avatar
  • 2,106
7 votes
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Why do zoologists classify sponges as animals rather than plants?

Organisms are classified, not by their behavior, but by their phylogeny (evolutionary relationships). Sponges have unique and complex molecules in their intracellular matrix that developed in a common ...
Karl Kjer's user avatar
  • 7,663
7 votes
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In lichen, do the fungi consume the oxygen produced by algae?

Exchange of gases between lichen symbionts has been demonstrated for Flavoparmelia caperata. Note that this is a foliose lichen species, though the findings may be generalizable to marine lichen. We ...
acvill's user avatar
  • 8,296
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/...
aesthete's user avatar
  • 351
6 votes
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Where do all the NAD+s come from?

There is of course a pathway that synthesizes NAD+ de novo, usually from tryptophan, aspartic acid or vitamin B3, or salvaged from compounds like nicotinic acid, nicotinamide. You can read more about ...
Krzysztof Czarnecki's user avatar
6 votes

Could humans breathe if the average methane content of the atmosphere increased to 1%?

Methane is biologically inert and can only act as an asphyxiant at high concentrations by displacing oxygen. An environmental exposure limit has been set at 5,000 ppm, though 10,000 ppm (1%) had no ...
canadianer's user avatar
  • 17.7k
6 votes

Is there any organism that is born with all the nutrients and resources needed for their entire lifetime?

You may need to clarify your question: As written, this would be the biological equivalent of a perpetual motion machine. No such organism could reproduce without either violating the first and second ...
Alex Reynolds's user avatar
6 votes
Accepted

Do humans emit more carbon through respiration or defecation?

The short answer In a comparison between exhaled and faecal carbon, exhaled carbon wins. The long answer Warning: Assumptions, approximations and averages ahead. Calculating faecal carbon excretion ...
Adhish's user avatar
  • 1,307
6 votes
Accepted

Will obligate aerobic bacteria die if placed in a buffer solution even in the presence of oxygen?

Answer No. There is ample evidence that: Most non-extremophilic bacteria grow over a broad range of external pH values, from 5.5 – 9.0, and maintain a cytoplasmic pH that lies within the narrow range ...
David's user avatar
  • 25.7k
6 votes

Why is the partial pressure of oxygen in blood same as that in alveoli

There are three unfounded assumptions in your equation that I can see. You're treating partial pressure as a concentration. Partial pressures are not concentrations, though they're convenient ...
Bryan Krause's user avatar
  • 45.6k
5 votes

How does the body switch between aerobic and anaerobic respiration?

Nice question. Now a perfect answer should include all the regulatory steps involved in this transition (a lot) and all the places where a change of metabolic fluxes occur. But, the question can be ...
stochastic13's user avatar
  • 4,679
5 votes
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How did mitochondria make energy long ago?

You are asking a very interesting question. As you correctly mention, the substrates of mitochondrial metabolism (TCA or Krebs Cycle) are pyruvate and NADH, and, through oxidative reactions, ATP is ...
rlluc's user avatar
  • 134
5 votes
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Why do bacteria eat enamel?

While I can't find any specific sources regarding bacteria eating enamel, I highly doubt this is what's happening in our mouths. I doubt this because your point is likely true - minerals in enamel ...
PreMedHopeful's user avatar

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