Cómo realizan el intercambio de gases los animales más primitivos

Up to what percentage of the world's flora consisted of cycads during the triassic period? 100% 75% 50% 20%

Northern switzerland has a fairly cold climate caused by sea winds from the atlantic ocean but souther switzerland tends to be much warmer and sunnier, what could cause this difference?

Amolecule that receives and sends signals is called