What eats only producers? (plants & plant like organisms)

How do diseases caused by bacteria and diseases caused by viruses react to antibiotics?

Which blood cell spend most of their time in the lymphatic system?

What did not occur in the proterozoic eon a)the oxygen levels increase greatly in the atmosphere, b)the emergence of the eukarya , c)muti cella’s eukaryotic organisms began to diversify, d)anaerobic bacteria kept thriving with more oxygen