How does heart rate change during and after an exercise is performed for two different periods of time?

Nucleic acid certain protein cell membranes certain carbohydrates

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

Which phase of the cell cycle ensures that identical copies of the dna are made for daughter cells?