Which diagram shows the human double circulatory system?

• A

• B

• C

• D

How often must a blood cell in the renal artery pass through the heart before it again reaches the renal artery?

• once

• twice

• three times

• four times

Which type of cell is found in the greatest numbers in blood?

• Red blood cell

• White blood cell

• Platelets

• Protein

What happens to breathing and heart rate during exercise?

• Breathing rate increases and heart rate decreases

• They both increase

• They both decrease

Why is the left wall of the heart have a thicker layer of muscle than the right side?

• To stop the blood flowing backwards

• To push the blood with more force at high pressure so it goes to all body cells.

• To push the blood at high pressure to the lungs.

What do platelets do?

• They stick together and make fibres that make scabs (blood clots) that stop pathogens entering the blood or stop you bleeding to death.

• They form your immune system and destroy pathogens.

• They carry oxygen around the body attached to haemoglobin.

What other names are given to red blood cells and also white blood cells?

• Lymphocytes (red blood cells) and phagocytes and erythrocytes (white blood cells).

• Erythrocytes (red blood cells) and phagocytes and lymphocytes (white blood cells).

• Phagocyctes (red blood cells) and lymphocytes and erythrocytes (white blood cells).

What do phagocytes do?

• Engulf (surround) microbes and digest them.

• Produce antibodies.

• Release a toxin that kills pathogens.

Why do arteries have a thick muscle layer?

• To provide energy for the blood vessel.

• To prevent the blood flowing backwards.

• To help withstand the high pressure blood, also to contract to control blood flow.

List the structures in the circulatory system the blood travels through from vena cava to aorta.

• Vena cava, lungs, pulmonary vein, left atrium, left ventricle, aorta, right atrium, right ventricle, pulmonary artery,

• Vena cava, left atrium, right ventricle, pulmonary vein lungs, pulmonary artery, right atrium, left ventricle, aorta

• Vena cava, right atrium, right ventricle, pulmonary artery, lungs, pulmonary vein, left atrium, left ventricle, aorta