If plants and animals have lived on earth for million of years, how has the composition of air allowed?

Question

.....and still does?

thankyou for the time!

Answer 1

Carbon monoxide is wrong... Carbon dioxide.

plants produce oxygen and animals produce carbon dioxide.

Answer 2

Plants absorb carbon monoxide and give off oxygen.

humans and animals draw in oxygen and give off carbon monoxide.  So we need each other to survive.  When there becomes more people than plants to give off oxygen then we die.  Plants can live without us, but we cannot live without plants.  Especially trees.

Answer 3

How has the composition of air allowed what?

Answer 4

I think you want to know how the iar composition has changed over the millenia.  In times of High oxygen the animals get bigger, dinos and the mega fauna of the last ice age.  When animals get big, alot of Carbon dioxide is given off.  This allows for the plants populations to get bigger and then the plants use up the carbon dioxide and give off oxygen.  The plants cycle with the animals in this way over thousands of years.