Question

In humans, oxygen is delivered to the cells of the body by ______.

A) an open circulatory system
B) diffusion and facilitated diffusion
C) a closed circulatory system
D) diffusion

Answer 1

Humans have a closed circulatory system that delivers oxygen to the cells of the body through blood vessels.

Step-by-step explanation:

Humans have a closed circulatory system that delivers oxygen to the cells of the body. In a closed circulatory system, the blood is contained within blood vessels, which allows for more efficient transport of oxygen. This is in contrast to an open circulatory system, where the blood is not contained in vessels and is more limited in its ability to deliver oxygen.