15) Regarding human blood types, how many possible alleles exists? OA.) 3 OB. N4 OC.) 6 Save Not Graded

Describe the response the kidneys have to dehydration and excessive water intake. what happens to the concentration of urine in each case ?

What controls activities within a eukaryotic cell?

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