I don't understand your entire question (the last seven words). If this is homework, we aren't allowed to give you the answer (site rules), but will give you clues if you tell us your answer and it's wrong.

What do you think the name of the gas is?

No its not homework.. I think its oxygen?

Yes, it's oxygen.

What does this mean: "where has low leavel of this gas?"

Oh I meant where has a low level of this gas in the biosphere but that is OK I understand no I think.. ahh biology is just so hard and confusing! Thank you very much for your help

So, this was homework?

No I'm studying

Do you understand why people get upset when forests and jungles get cut down and burned?

We breathe out carbon dioxide, and plants/trees "breathe" it in. Then the plants/tress produce oxygen, and we breathe that in.

No

Mammals breathe in oxygen, then breathe out carbon dioxide.

Plants breathe in carbon dioxide, then breathe out oxygen.

Do you see a pattern, a cycle?

Ahh yes I see