DNA and RNA differ in the following way(s): 1. DNA has a phosphate and RNA does not
2. DNA and RNA have different 5 carbon sugars
3. DNA and RNA have the same nucleotides
4. Both A and C

Which of the following is a reason why early living organisms on earth could not have survived on the surface? 1. the lack of an ozone layer 2. the lack of oxygen in the atmosphere 3. the fact that these organisms were single-celled