Grade 6 Science Exam Questions: Circulatory & Respiratory System Worksheet for 12-Year-Olds

Instructions

Read each question carefully and answer to the best of your ability. The questions cover key concepts of the circulatory and respiratory systems and how they work together.

1. What is the primary function of the red blood cells in the circulatory system?

   a) To fight infections and diseases.
   b) To help the blood clot after an injury.
   c) To carry oxygen from the lungs to the body's cells.
   d) To transport nutrients and hormones.



2. Fill in the blanks to describe the path of air into the lungs:

   Air enters the body through the nose or mouth, travels down the (a)______________, splits into two tubes called (b)______________, and finally reaches millions of tiny air sacs in the lungs called (c)______________.



3. In your own words, explain the main difference between an artery and a vein.

   __________________________________________________________________________________________________

   __________________________________________________________________________________________________



4. Which large, dome-shaped muscle located below the lungs is the main muscle used for breathing?

   a) Bicep
   b) Trachea
   c) Diaphragm
   d) Atrium



5. Describe the process of gas exchange that occurs in the alveoli. What two gases are exchanged, and where do they go?

   __________________________________________________________________________________________________

   __________________________________________________________________________________________________



6. The heart has four chambers. The top two receiving chambers are called the _______________, and the bottom two pumping chambers are called the _______________.


7. Is the following statement True or False? Explain your answer.

   "The right side of the heart pumps oxygen-rich blood to the entire body."

   True / False (Circle one)

   Explanation: _____________________________________________________________________________

   __________________________________________________________________________________________________



8. Match the part of the circulatory system with its correct function.

   1. Heart	A. Tiny blood vessels where gas and nutrient exchange happens.
   2. Capillaries	B. Cell fragments that help stop bleeding by forming clots.
   3. White Blood Cells	C. The muscular organ that pumps blood throughout the body.
   4. Platelets	D. Part of the immune system; they fight off germs and infections.

   1. _____ 2. _____ 3. _____ 4. _____



9. Why is the circulatory system often called the body's "transportation system"?

   __________________________________________________________________________________________________

   __________________________________________________________________________________________________



10. Complete the journey of waste gas from a muscle cell back to the air. Fill in the blanks.

    A muscle cell produces (a)___________________ as a waste product. This gas moves from the cell into the blood inside tiny (b)___________________. This blood, which is poor in oxygen, travels through veins back to the (c)_______________, which then pumps it to the (d)_______________ to be exhaled.

Answer Key

1. c) To carry oxygen from the lungs to the body's cells. Red blood cells contain hemoglobin, which binds to oxygen.
2. (a) trachea (or windpipe), (b) bronchi, (c) alveoli
3. Arteries carry oxygenated blood away from the heart to the rest of the body (they are thick and muscular). Veins carry deoxygenated blood back towards the heart from the body (they have valves to prevent backflow). (Note: The exception is the pulmonary artery/vein).
4. c) Diaphragm
5. In the alveoli, oxygen from the inhaled air passes through the thin walls into the capillaries (bloodstream). At the same time, carbon dioxide, a waste gas, passes from the blood into the alveoli to be exhaled.
6. The top two receiving chambers are called the atria (or atriums), and the bottom two pumping chambers are called the ventricles.
7. False. The right side of the heart receives deoxygenated (oxygen-poor) blood from the body and pumps it only to the lungs. The left side of the heart receives oxygen-rich blood from the lungs and pumps it to the entire body.
8. 1. C   2. A   3. D   4. B
9. It is called the "transportation system" because it uses blood to transport essential materials like oxygen, nutrients, and water to all the cells in the body, and it carries away waste products like carbon dioxide.
10. (a) carbon dioxide, (b) capillaries, (c) heart, (d) lungs