Why are interactions between biotic factors necessary

Which of the following was not a major animal on land during the carboniferous period? amphibians insects both a and b none of the above

Which type of transport is responsible for oxygen entering into blood cells? a. vesicle b.passive c. facilitated d.active b.passive

What are some of the immune functions of the lymphatic system? a. cleaning red blood cells from the blood and creating lymph fluids b.transporting lymph to the tissues and creating lymph fluids c.removing infectious agents and making white blood cells d.making red blood cells and removing infectious agents