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 ...
user avatar
42 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 “…...
user avatar
  • 22.4k
25 votes

Why don't we breathe nitrogen when it makes up most of the air?

Animals use oxygen as a chemical energy source because oxygen gas can react with many other compounds to form oxides, which releases energy and happen spontaneously. Both carbon and nitrogen can be ...
user avatar
  • 27.5k
21 votes
Accepted

What are the side-effects of long-term liquid breathing?

Overview. This is a very interesting question. The ideas behind this have been around for a while and the methods are covered in great detail elsewhere. The overall answer to the hypothetical ...
user avatar
  • 11.2k
19 votes
Accepted

Why don't we breathe nitrogen when it makes up most of the air?

I'd argue that we do "breathe" all those gases. Air that we inhale (at sea level) is about 78% N$_2$, 20.9% O$_2$, 1% argon, and smaller percentages of CO$_2$, neon, methane, etc. So all those gases ...
user avatar
  • 12.1k
18 votes
Accepted

How can we differentiate between respiration and breathing?

There are two uses of the term respiration: physiological respiration and cellular respiration Physiological respiration involves the intake of outside oxygen and its distribution to the tissues of ...
user avatar
  • 17.5k
17 votes
Accepted

Why do you die if you cannot breathe?

Short answer This is a difficult question to answer. As far as I am aware, asphyxiation results in excitotoxicity, which causes unconsciousness, brain damage and eventually, death. Background ...
user avatar
  • 51.1k
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 ...
user avatar
11 votes

How can we differentiate between respiration and breathing?

Breathing is a part of respiration but respiration is not a part of breathing. Breathing is a process through which oxygen is taken into the body for use in respiration. This involves physical ...
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 ...
user avatar
  • 22.4k
10 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 ...
user avatar
  • 22.4k
9 votes
Accepted

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 ...
user avatar
  • 7,969
8 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 ...
user avatar
  • 7,564
7 votes

Why don't we breathe nitrogen when it makes up most of the air?

Nitrogen is much less reactive than oxygen. Indeed, if I haven't totally forgotten my long-ago chemistry courses, most chemical reactions involving N2 are energy-consuming. Thus you get nitrogen ...
user avatar
  • 3,613
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'...
user avatar
  • 14.7k
7 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 ...
user avatar
7 votes
Accepted

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 ...
user avatar
  • 2,048
7 votes
Accepted

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 ...
user avatar
  • 7,569
7 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'. ...
user avatar
  • 5,196
7 votes
Accepted

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 ...
user avatar
  • 7,564
6 votes
Accepted

How long can a bee surive in a jar?

Assuming the jar is airtight-- I think your oxygen consumption rate may be too high and that 40$\mu l$ per hour$^1$ might be closer but since it's a high figure anyway we can use it. 40 $\mu l$ per ...
user avatar
  • 2,759
6 votes

How can we differentiate between respiration and breathing?

An addition to previous answers plus some clarification The term respiration originally meant breathing i.e inhaling and exhaling (See here). It was believed that it is the oxygen and in turn the act ...
user avatar
  • 35.1k
6 votes

How is AMP "recharged" to become ATP in a cell?

AMP is first converted to ADP in the reaction AMP + ATP $\leftrightarrow$ 2 ADP catalyzed by adenylate kinase. So one phophate group is transfered from ATP to AMP, resulting in two ADP molecules. ...
user avatar
  • 5,595
6 votes
Accepted

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 ...
user avatar
  • 216
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/...
user avatar
  • 351
6 votes
Accepted

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 ...
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 ...
user avatar
  • 17.5k
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 ...
user avatar
  • 22.4k
6 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 ...
user avatar
  • 36k

Only top scored, non community-wiki answers of a minimum length are eligible