Where are red blood cells produced?

• liver

• heart

• bone marrow

• lungs

What valve is found between the right atrium and right ventricle?

• tricuspid valves

• aortic valves

• pulmonic valves

• mitral valves

They play part in the clotting of blood.

• platelets

• plasma

• red blood cells

• white blood cells

Which component of the blood has a nucleus?

• plasma

• platelets

• red blood cells

• white blood cells

What mineral is present in the chemical pigment of a red blood cell?

• calcium

• fluorine

• iron

• magnesium

Veins have openings or lumens which are wider than the arteries.

• True

• False

Which of the following is not a formed element?

• plasma

• platelets

• red blood cells

• white blood cells

Which of the following is responsible for sealing the wound?

• plasma

• white blood cells

• platelets

• red blood cells

Which of the following is not true about human circulatory system?

• The atria pump blood out of the heart.

• Our veins have thinner walls than our arteries.

• Leukocytes fight microbes that may cause diseases.

• Our heart rate changes in response to our physical activity.

Blood platelets or thrombocytes are not true cells but are fragments of __________________.

• erythrocytes

• leukocytes

• cytoplasm

• nucleus