Biology please help me?

The ______ is a vital organ, and its functioning is essential to life. (Points : 1) spleen appendix heart none of the above Question 2. 2. Simple animals use their ______ as an exchange point for materials. (Points : 1) skin heart liver ... show more The ______ is a vital organ, and its functioning is essential to life. (Points : 1)
spleen
appendix
heart
none of the above





Question 2. 2. Simple animals use their ______ as an exchange point for materials. (Points : 1)
skin
heart
liver
none of the above





Question 3. 3. What are the lower chambers of the vertebrate heart called? (Points : 1)
ventricles
atria
valves
none of the above





Question 4. 4. ______ carry blood away from the heart. (Points : 1)
Veins
Arteries
Capillaries
none of the above





Question 5. 5. Amphibians have a ______-chambered heart. (Points : 1)
four
three
two
one





Question 6. 6. The gradual buildup of ______ usually results in a blockage of coronary arteries. (Points : 1)
fat
cholesterol
both a and b
none of the above





Question 7. 7. Damaged heart tissue permanently loses its _____. (Points : 1)
blood flow
flexibility
both a and b
none of the above





Question 8. 8. ______ are responsible for an immune response. (Points : 1)
white blood cells
red blood cells
platelets
none of the above





Question 9. 9. ______ aid in the clotting of blood. (Points : 1)
white blood cells
red blood cells
platelets
none of the above





. 10. People suffering from the genetic disease ______ have blood that cannot clot. (Points : 1)
hemophilia
anemia
leukemia
none of the above
2 answers 2