Why do plants breathe carbon dioxide? Why don't they breathe oxygen, or hydrogen, or some other gas?

Question

What is it about carbon dioxide that gives plants sustenance and energy?

I am aware of the fact that humans and animals breathe oxygen and exhale carbon dioxide, and plants breathe carbon dioxide and exhale oxygen. This balance has served to sustain our planet.

But that isn't the question. What purpose does carbon dioxide in particular serve plants? Does it help fuel photosynthesis? And if so, how?

It's a silly notion to think that plants breathe CO2 only because animals exhale it. That it's simply the "balance" of things and that's how they are. If the reason was only this "balance," then why don't humans breathe carbon dioxide and plants breathe oxygen?

There must be some function that carbon dioxide serves for plants.

Answer 1

Plants DO breathe oxygen, the same way we do. Respiration is the most effective energy producing process there is.
Plants, however, can perform another process (photosynthesis) in which they take up CO2 and use the energy of sunlight to build up sugars and starches from this CO2. THEN they can use these starches in the process of respiration, the same way we do (we take sugars and "use" oxygen to take out the energy contained in them)
So the only difference betwen us and plants is that they make their own fuel out of CO2 , but we must eat it. But we both breathe oxygen in order to get the energy out of it.
As to why the don't breathe hydrogen... you'd have to ask god.... but normally when hydrogen combines with things it requires energy instead of giving rise to it, so it wouldn't be too advantageous
So it's not that we produce the CO2 so plants can live. Plants could live without animals, we're the parasites here hehehehe

Answer 2

That is quite a question, one which I am not sure has a real answer, you could just answer it by saying it is how they are built, it is how they live, it is always how they have been. Why do we breath oxygen, because it is just what we need to survive, maybe at the time the plant life was born on this planet the atmosphere was more carbon dioxide, who really knows.

Answer 3

The balance of nature is working here. We, and other animals exhale oxygen as a byproduct of our metabolism. Plant use that carbon dioxide and remove the carbon molecule and release oxygen for us to use.

Answer 4

plants transpire more oxygen than co2 in the day, at night they transpire more co2 than O2.

sunlight produces the chemical reaction with Co2 and water H2O to produce sugars that the plant feeds on C6 H12 O6 (sucrose formula is something like this) oxygen is emmitted after this chemical reaction takes place

= Carbon dioxide is made into sugars

Answer 5

Plants, like most living things on earth, are carbon-based. They obtain their carbon from CO2 while we obtain ours from them, or from eating other animals that eat them. Plants being the primary producers in all foodchains must take in some form of Carbon, and the most readily available and abundant source is CO2. Bicarbonates in soil are in limited supply.

Answer 6

Plants have to make their own food (glucose = C6H12O6) during photosynthesis. CO2 is their carbon source. CO2 is also one of the most abundant gases, making it easy to obtain. Since plants don't move they need a source that is everywhere.

Answer 7

It's a trade off, they give us oxygen; If they breathed oxygen we would have problems, not everyone can take and no one give.

Answer 8

I have a talking tree in my backyard. I will ask him for you!