Carbon dioxide, ethanol, and energy are the products when anaerobic respiration occurs

in oxygen

in the presence of nitrogen

in yeast cells

in an animal cell

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