Organisms that have ventilation systems will draw in air (or
water) that is rich in oxygen and will draw out air that has carbon dioxide. This
is essential for a multicellular organism to thrive because carbon dioxide is
harmful for an organism since carbon dioxide (CO2) is a waste product. Such is
the system that contain veins, capillaries and arteries. On the other hand, organisms
that don’t have ventilation system, can survive without it because they are
single-celled and the path for the nutrients and needed oxygen is so short that
they can efficiently exchange gases at the surface.
