Plasma makes up more than half of the volume of a normal blood sample.
Correct Answer
True
True. In a centrifuged sample of normal blood, plasma is the largest component by volume, with red blood cells making up most of the rest and the buffy coat only a tiny fraction.
Category: Blood Composition
Question 2
Whole blood is less viscous than water.
Correct Answer
False
False. Whole blood is more viscous than water because of its formed elements and plasma proteins, and this thickness affects blood pressure and flow.
Category: Blood Composition
Question 3
Anti-Rh antibodies form naturally in Rh-negative people early in life, without exposure to the Rh antigen.
Correct Answer
False
False. An Rh-negative person makes anti-Rh antibodies only after being sensitized by exposure to Rh-positive red cells, such as through a transfusion or the birth of an Rh-positive baby. In contrast, anti-A and anti-B antibodies do arise naturally early in life.
Category: Blood Typing
Question 4
In the fetus, blood cell formation begins in the thymus.
Correct Answer
False
False. Fetal blood cell formation begins in the yolk sac and then shifts to the fetal liver, spleen and lymphatic tissue before red bone marrow takes over.
Category: Formed Element Production
Question 5
All formed elements of blood arise from one type of stem cell called the hemocytoblast.
Correct Answer
True
True. The hemocytoblast, or hematopoietic stem cell, gives rise to myeloid and lymphoid stem cells, which in turn produce every type of formed element.
Category: Formed Element Production
Question 6
A person with type A blood has naturally occurring anti-B antibodies in the plasma.
Correct Answer
True
True. Type A red cells carry the A antigen, and the plasma contains anti-B antibodies that develop early in life. These antibodies would attack type B red cells in a mismatched transfusion.
Category: Blood Typing
Question 7
Mature red blood cells contain a nucleus and mitochondria.
Correct Answer
False
False. Mature red blood cells lack a nucleus and mitochondria. Without mitochondria they make ATP anaerobically and do not use up the oxygen they carry.
Category: Erythrocytes
Question 8
Each heme group of hemoglobin contains an iron ion that binds oxygen.
Correct Answer
True
True. Each heme group holds one iron ion, and that iron reversibly binds one oxygen molecule, which is why iron is essential for red blood cell function.
Category: Erythrocytes
Question 9
Reticulocytes are immature red blood cells, and their count reflects the rate of red blood cell production.
Correct Answer
True
True. Reticulocytes still contain remnants of ribosomes and mature into erythrocytes within a day or two of entering the blood, so a rising count signals increased production.
Category: Erythrocytes
Question 10
A normal red blood cell circulates for about 10 days before it is removed.
Correct Answer
False
False. A normal red blood cell circulates for about 120 days before macrophages in the spleen, liver and bone marrow remove it.
Category: Erythrocytes
Question 11
Sickle cell anemia is caused by an abnormal form of hemoglobin.
Correct Answer
True
True. Sickle cell anemia is an inherited disorder in which abnormal hemoglobin causes red cells to become rigid and sickle shaped, so they break down early and can block small vessels.
Category: Erythrocytes
Question 12
Polycythemia is an abnormally low number of red blood cells.
Correct Answer
False
False. Polycythemia is an abnormally high number of red blood cells, which raises the hematocrit and makes the blood more viscous.
Category: Erythrocytes
Question 13
Leukocytes leave the bloodstream by squeezing between the cells of the capillary wall.
Correct Answer
True
True. This movement, called emigration or diapedesis, lets white blood cells reach tissues where they fight infection and clear debris.
Category: Leukocytes and Platelets
Question 14
Basophils are the most abundant type of leukocyte.
Correct Answer
False
False. Basophils are the least abundant leukocytes. They release histamine, which promotes inflammation, and heparin, which opposes clotting.
Category: Leukocytes and Platelets
Question 15
T lymphocytes complete their maturation in the thymus.
Correct Answer
True
True. T cells arise from lymphoid stem cells in the bone marrow and then migrate to the thymus to mature, while B cells mature in the bone marrow.
Category: Leukocytes and Platelets
Question 16
Leukopenia is an abnormally high white blood cell count.
Correct Answer
False
False. Leukopenia is an abnormally low white blood cell count, which leaves a person less able to fight infection. An abnormally high count is leukocytosis.
Category: Leukocytes and Platelets
Question 17
The extrinsic pathway of coagulation is triggered by tissue factor released from damaged tissue.
Correct Answer
True
True. Tissue factor, released by damaged cells outside the blood, combines with factor VII and calcium to activate factor X, starting the fast extrinsic pathway.
Category: Hemostasis
Question 18
Plasmin is the enzyme that converts fibrinogen into fibrin.
Correct Answer
False
False. Thrombin converts fibrinogen into fibrin. Plasmin does the opposite job, breaking down fibrin to dissolve a clot during fibrinolysis.
Category: Hemostasis
Question 19
The liver requires vitamin K to synthesize several clotting factors.
Correct Answer
True
True. Vitamin K is needed for the liver to make several clotting factors, including prothrombin, so a vitamin K deficiency can cause excessive bleeding.
Category: Hemostasis
Question 20
Hemophilia A is caused by a deficiency of clotting factor IX.
Correct Answer
False
False. Hemophilia A is caused by a deficiency of clotting factor VIII. A deficiency of factor IX causes hemophilia B.
Category: Hemostasis