why would the lives of multi cellular animals be impossible if prokaryotic and protistan organisms did not exist?

Question 1: In some developing countries, antibiotics can be purchased without a prescription. why do you think this is done? what biological consequences would you predict?

Question 2: why would the lives of multi cellular animals be impossible if prokaryotic and protistan organisms did not exist?

Question 3: the discovery of penicillin revolutionized treatment of bacterial diseases, however, penicillin is now rarely prescribed. why is this?

Question 4: what ecological consequences would occur if humans, using a new and deadly fungicide destroyed all fungi on earth?