Which protein is the most abundant in blood plasma?
Albumin
✓
Fibrinogen
Gamma globulin
Transferrin
Correct Answer
Albumin
Albumin, made by the liver, is the most abundant plasma protein and the main contributor to the osmotic pressure that holds water in the blood. Fibrinogen is a clotting protein present in much smaller amounts. Gamma globulin refers to antibodies, which make up only part of the globulin fraction. Transferrin is a minor transport protein that carries iron.
Category: Blood Composition
Question 2
After a blood sample is centrifuged, which formed elements make up the thin buffy coat?
Erythrocytes only
Leukocytes and platelets
✓
Plasma proteins and water
Electrolytes and gases
Correct Answer
Leukocytes and platelets
The buffy coat is the thin, pale layer between the plasma and the packed red cells, and it holds the white blood cells and platelets. Erythrocytes only describes the dense bottom layer. Plasma proteins and water make up the top plasma layer. Electrolytes and gases are dissolved in the plasma and do not form a visible layer.
Category: Blood Composition
Question 3
Serum differs from plasma in that serum lacks which components?
Albumin
Water
Clotting factors
✓
Electrolytes
Correct Answer
Clotting factors
Serum is the fluid left after blood clots, so the clotting factors such as fibrinogen have been used up and removed. Albumin remains in serum and is its most abundant protein. Water is still the main component of serum. Electrolytes remain dissolved in serum as they are in plasma.
Category: Blood Composition
Question 4
Which range describes the normal pH of arterial blood?
6.85 to 6.95
7.05 to 7.15
7.55 to 7.65
7.35 to 7.45
✓
Correct Answer
7.35 to 7.45
Normal blood is slightly alkaline, with a pH between 7.35 and 7.45 maintained by buffer systems. The range 6.85 to 6.95 is acidic and incompatible with normal function. The range 7.05 to 7.15 indicates severe acidosis. The range 7.55 to 7.65 indicates alkalosis.
Category: Blood Composition
Question 5
In a healthy adult, where are most formed elements of blood produced?
Red bone marrow
✓
Yellow bone marrow
Liver
Thymus
Correct Answer
Red bone marrow
In adults, blood cells are produced mainly in red bone marrow, found in places such as the vertebrae, sternum, pelvis and the proximal ends of the femur and humerus. Yellow bone marrow is mostly fat and does not normally produce blood cells. The liver produces blood cells in the fetus but not normally in the adult. The thymus is where T cells mature, not where formed elements are generated.
Category: Formed Element Production
Question 6
Erythropoietin, the hormone that stimulates red blood cell production, is secreted mainly by which organ in response to low blood oxygen?
Liver
Kidneys
✓
Spleen
Thymus
Correct Answer
Kidneys
Cells in the kidneys release erythropoietin when they sense low oxygen, and the hormone stimulates red bone marrow to increase erythrocyte production. The liver is the main source of thrombopoietin and plasma proteins rather than the main source of this hormone. The spleen stores platelets and removes old red cells. The thymus is a site of T cell maturation.
Category: Formed Element Production
Question 7
Which formed elements arise from lymphoid stem cells?
Neutrophils
Megakaryocytes
Lymphocytes
✓
Erythrocytes
Correct Answer
Lymphocytes
Lymphoid stem cells give rise to lymphocytes, including B cells, T cells and natural killer cells. Neutrophils come from the myeloid line. Megakaryocytes, the platelet-forming cells, also come from myeloid stem cells. Erythrocytes are produced from myeloid stem cells as well.
Category: Formed Element Production
Question 8
Platelets are cytoplasmic fragments of which large bone marrow cells?
Monocytes
Myeloblasts
Reticulocytes
Megakaryocytes
✓
Correct Answer
Megakaryocytes
Megakaryocytes are very large cells in the red bone marrow that shed pieces of their cytoplasm into the blood, and these membrane-bound fragments are platelets. Monocytes are agranular leukocytes that become macrophages. Myeloblasts are precursors of the granular leukocytes. Reticulocytes are immature red blood cells.
Category: Formed Element Production
Question 9
What does the biconcave disc shape of a red blood cell provide?
Increased surface area for gas exchange
✓
Room for a large nucleus
Faster cell division
Storage of glycogen
Correct Answer
Increased surface area for gas exchange
The biconcave shape gives a red blood cell a large surface area relative to its volume, which speeds diffusion of oxygen and carbon dioxide, and it also lets the cell bend through narrow capillaries. Room for a large nucleus is wrong because mature red cells have no nucleus. Faster cell division is wrong because mature red cells cannot divide. Storage of glycogen is not a role of the cell's shape.
Category: Erythrocytes
Question 10
How many oxygen molecules can one hemoglobin molecule carry when fully loaded?
One
Four
✓
Two
Eight
Correct Answer
Four
Hemoglobin has four globin chains, each holding one heme group with an iron ion, and each iron binds one oxygen molecule, so one hemoglobin carries four. One would be true of a single heme group only. Two undercounts the chains. Eight would require twice as many heme groups as hemoglobin has.
Category: Erythrocytes
Question 11
When worn-out red blood cells are broken down, the non-iron part of heme is converted to which yellow pigment that the liver secretes into bile?
Urea
Creatinine
Bilirubin
✓
Ferritin
Correct Answer
Bilirubin
Macrophages convert the non-iron part of heme to green biliverdin and then to yellow bilirubin, which travels to the liver and is excreted in bile. Urea is a nitrogen waste made from amino acid breakdown. Creatinine is a waste product of muscle metabolism. Ferritin is a protein that stores iron, not a pigment made from heme.
Category: Erythrocytes
Question 12
Which type of anemia is the most common worldwide?
Sickle cell anemia
Aplastic anemia
Pernicious anemia
Iron deficiency anemia
✓
Correct Answer
Iron deficiency anemia
Iron deficiency anemia is the most common type, because without enough iron the body cannot make adequate heme for hemoglobin. Sickle cell anemia is an inherited hemoglobin disorder that affects a smaller population. Aplastic anemia results from failure of the bone marrow and is uncommon. Pernicious anemia results from poor vitamin B12 absorption and is far less common.
Category: Erythrocytes
Question 13
Hemolytic disease of the newborn can develop when an Rh-negative mother who has anti-Rh antibodies carries a fetus with which blood type?
Rh positive
✓
Rh negative
Type O
Type AB
Correct Answer
Rh positive
If an Rh-negative mother has been sensitized, her anti-Rh antibodies can cross the placenta and destroy the red blood cells of an Rh-positive fetus. Rh negative is wrong because a fetus whose cells lack the Rh antigen is not attacked. Type O and Type AB describe the ABO group, which is not the cause of this Rh-related disease.
Category: Blood Typing
Question 14
Which leukocytes are the most numerous in the blood of a healthy adult?
Lymphocytes
Neutrophils
✓
Monocytes
Eosinophils
Correct Answer
Neutrophils
Neutrophils make up the largest share of circulating white blood cells and are fast-acting phagocytes against bacteria. Lymphocytes are the second most common type. Monocytes make up a small percentage of leukocytes. Eosinophils are also a small fraction of the total.
Category: Leukocytes and Platelets
Question 15
After leaving the bloodstream and entering tissues, monocytes mature into which phagocytic cells?
Plasma cells
Mast cells
Macrophages
✓
Platelets
Correct Answer
Macrophages
Monocytes that move into tissues enlarge and become macrophages, which engulf pathogens, debris and worn-out cells. Plasma cells develop from B lymphocytes and secrete antibodies. Mast cells are tissue cells that release histamine and do not develop from monocytes. Platelets are cell fragments from megakaryocytes.
Category: Leukocytes and Platelets
Question 16
Eosinophil numbers typically rise during allergic reactions and during infection by which type of pathogen?
Bacterial infections
Viral infections
Fungal spores
Parasitic worms
✓
Correct Answer
Parasitic worms
Eosinophils help defend against parasitic worms and are elevated in allergies and parasitic infections. Bacterial infections are mainly fought by neutrophils. Viral infections typically raise lymphocyte counts. Fungal spores are not the infection characteristically linked to high eosinophil counts.
Category: Leukocytes and Platelets
Question 17
Which white blood cells differentiate into plasma cells that secrete antibodies?
B cells
✓
Cytotoxic T cells
Natural killer cells
Helper T cells
Correct Answer
B cells
When activated, B cells divide and differentiate into plasma cells, which secrete antibodies as part of humoral immunity. Cytotoxic T cells directly kill infected or abnormal cells rather than making antibodies. Natural killer cells destroy virus-infected and cancer cells without producing antibodies. Helper T cells coordinate immune responses but do not become antibody-secreting cells.
Category: Leukocytes and Platelets
Question 18
Which is the first event of hemostasis after a blood vessel is injured?
Platelet plug formation
Vascular spasm
✓
Coagulation
Fibrinolysis
Correct Answer
Vascular spasm
Hemostasis begins with vascular spasm, a sharp contraction of the smooth muscle in the vessel wall that reduces blood flow through the injury. Platelet plug formation is the second step. Coagulation, the formation of a fibrin clot, is the third step. Fibrinolysis is the later breakdown of the clot after the vessel has healed.
Category: Hemostasis
Question 19
In the common pathway of coagulation, thrombin converts fibrinogen into which insoluble protein that forms the mesh of a clot?
Albumin
Plasmin
Fibrin
✓
Collagen
Correct Answer
Fibrin
Thrombin cleaves soluble fibrinogen into insoluble fibrin strands, which form a mesh that traps blood cells and platelets. Albumin is a plasma protein that regulates osmotic pressure and plays no role in the clot mesh. Plasmin is the enzyme that breaks down a clot. Collagen is a protein in the vessel wall that platelets stick to, not a product of fibrinogen.
Category: Hemostasis
Question 20
A person with type O blood has which antibodies in the plasma?
Anti-A antibodies only
Anti-B antibodies only
Neither anti-A nor anti-B
Anti-A and anti-B antibodies
✓
Correct Answer
Anti-A and anti-B antibodies
Type O red cells carry neither the A nor the B antigen, and the plasma contains anti-A and anti-B antibodies. Anti-A antibodies only describes type B blood. Anti-B antibodies only describes type A blood. Neither anti-A nor anti-B describes type AB blood.
Category: Blood Typing