What structure is changed during an enzyme reaction?

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

The negative impacts of nonnative species generally outweigh the positive impacts

Which kingdom includes some organisms that have no nucleus and can live in an environment with an extremely high salt content