1. Why is respiratory system very important to the body? a. It enables carbon dioxide to get into the body. b. It consists of body parts that help the body receive oxygen. c. It helps distribute carbon dioxide to the blood. d. It enables the blood to circulate in your body. 2. How does oxygen in the air get into the blood? a though the nose b. though the throat C. though the mouth d. though the tiny capillaries 3.What will happen to the cells of the body when there is absence of oxygen? a. The cells will continue to grow and multiply. b. The cells will be inactive. c. The cells will survive. d. The cells will die 4. How can you keep your heart strong? a eating heart-shaped candy b. doing activities like playing outside, riding your bike, and swimming C. Smoking d. sleeping 18 hours a day 5. What are tubes that carry blood back to the heart? a. arteries b. veins C. pipes d. tubes 6. Which of the following describes the correct passage of blood originating from the left leg? a. Vena cava left atrium right atrium - lungs- left ventricle -->right ventricle aorta b. Vena cava right atrium - left atrium - lungs → right ventricle -left ventricle + aorta c. Vena cava left atrium left ventricle-lungs → right atrium ->right ventricle aorta d. Vena cava - right atrium - right ventricle --- lungs left atrium ---left ventricle - aorta 7. What is the functional unit of the nervous system? a brain b. neurons C. muscles d. bones​