Problem:
Question 1: Compare and contrast the physical and chemical conditions on Earth at the time that life first arose with conditions today.
Question 2: From a physiological standpoint, discuss two reasons why animals could not have existed on early Earth.
Question 3: Explain how microbial metabolism altered the Earth's biosphere?
Question 4: How might life on Earth be different if cyanobacteria had not evolved? Explain
I dont need long explanation. Just few sentences of expanation.