High levels of may be teratogenic causing birth defects

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

What is the primary function of the nervous system?

Hemoglobin is a proton that carries oxygen around the body what is hemoglobin made from