Rich and Strange Aeons

I remember learning long ago that plants effectively undergo a kind of rest cycle based on when it's dark out. I don't remember the term for the cycle or process, but I remember the experiment to test it: if you take two identical plants (control and test) and interrupt the test subject's dark time with bursts of light every hour or two throughout the night, the plant ends up dying off. I'm pretty sure the result extends to having no dark time at all.

So, my answer's a cop-out -- I don't know how quickly we'd fry, but I don't think we'd last too long without plant life recycling CO2 for us.