Answer:
Oxygen
Explanation:
The circulatory system gets oxygen from the respriatory system and circulates it throughout the body.
Answer:
A concentration gradient occurs when the concentration of particles is higher in one area than another. In passive transport, particles will diffuse down a concentration gradient, from areas of higher concentration to areas of lower concentration, until they are evenly spaced.
Explanation:
Hope this helps c:
<span>A dichotomous key is very easy to use because it provides only two choices. </span>
3) there are more consumers than producers
Hopefully this helped and good luck.