Could single celled organisms produce enough O2

[kitkat]

Could single celled organisms produce enough oxygen without multi-cellular organisms existing for our atmosphere? The planet's only residents were single celled organisms for over half the earth's history. The majority of successful single celled organisms is determined by population status and its vital role in supporting other organisms ability to survive.

 

I do not see how we could emerge especially with so many complicated processes that require so much energy to produce and maintain during a lifespan. isn't the law of physics state that energy works to reduce itself?

 

It seems to me that single celled organisms could do just fine without larger life forms.

[CharonY]

I have no idea what your point is. Obviously single-celled organisms can do (and did) just fine by themselves. Also in the absence of oxygen.

[Mr Skeptic]

Yes, probably not, yes.