Welcome to Part 36 of our Free ASCP MLS Exam Practice Questions series. In this section, we focus on Hematology Physiology, covering the normal function and regulation of red blood cells, white blood cells, platelets, and hemoglobin.
Understanding hematology physiology is essential for MLS exam preparation, as it builds the foundation for interpreting both normal and pathological findings in the clinical laboratory.
🔹 Topics Covered in This Part
- Hemoglobin structure, function, and oxygen transport
- Hematopoiesis and bone marrow physiology
- Erythropoiesis and red blood cell function
- White blood cell development and immune roles
- Platelet production and mechanisms in hemostasis
60 MCQs (3101- 3160):
📘 How to Use These Practice Questions
- Each question is designed to test your understanding of normal physiology before diving into disease states.
- Questions will continue sequentially from the previous set — starting at Question 3101.
- At the end of each question set, answer keys with explanations will be provided to help reinforce key concepts.
- . Where is the majority of iron in an adult body found?
a) As hemosiderin in storage
b) As a constituent of hemoglobin
c) Bound to transferrin in the plasma
d) As a component of myoglobin - For hemoglobin to combine reversibly with oxygen, the iron must be in which state?
a) Complexed with haptoglobin
b) In the ferric (Fe³⁺) state
c) In the ferrous (Fe²⁺) state
d) Freely circulating in the cytoplasm - What is the main function of the hexose monophosphate shunt in the erythrocyte?
a) To regulate the level of 2,3-DPG
b) To provide energy for membrane maintenance
c) To provide reduced glutathione to prevent hemoglobin oxidation
d) To prevent the reduction of heme iron - What is the primary role of the spleen in a normal adult?
a) Storage of red blood cells
b) Production of red blood cells
c) Synthesis of erythropoietin
d) Removal of imperfect and aging cells - Which cell is responsible for the transport of oxygen and carbon dioxide?
a) Granulocytes
b) Erythrocytes
c) Lymphocytes
d) Thrombocytes - The action of erythropoietin is to primarily:
a) Shorten the replication time of granulocytes.
b) Stimulate RNA synthesis of erythroid cells.
c) Increase colony-stimulating factors from B lymphocytes.
d) Decrease the release of marrow reticulocytes. - Which cells are capable of producing antibodies and direct cytolysis?
a) Granulocytes
b) Thrombocytes
c) Lymphocytes
d) Erythrocytes - Phagocytosis is a primary function of which cell type?
a) Lymphocytes
b) Erythrocytes
c) Thrombocytes
d) Granulocytes - Which cells are the primary mediators of immediate hypersensitivity reactions?
a) Eosinophils
b) Reactive lymphocytes
c) Plasma cells
d) Basophils - Aspirin impairs platelet function by which mechanism?
a) Impairing von Willebrand factor
b) Inactivating cyclooxygenase, which blocks thromboxane A2 production
c) Decreasing amounts of arachidonic acid
d) Inactivating ADP and phospholipase A2 - In an infant, which gland is primarily responsible for producing lymphocytes?
a) Adrenal
b) Pituitary
c) Thymus
d) Thyroid - When the iron in hemoglobin is in the +3 (ferric) state, it is termed:
a) Carboxyhemoglobin
b) Sulfhemoglobin
c) Ferrihemoglobin
d) Methemoglobin - The process of phagocytosis in neutrophils is best described as a mechanism to:
a) Defend against parasites.
b) Mediate sensitivity reactions.
c) Kill and degranulate bacteria.
d) Neutralize products from mast cells. - What is the composition of a Howell-Jolly body?
a) RNA
b) Iron
c) Denatured Hemoglobin
d) DNA - In methemoglobin, which ion is bound to the heme group?
a) Fe²⁺
b) Fe³⁺
c) Ca²⁺
d) Mg²⁺ - An increased amount of cytoplasmic basophilia in a blood cell indicates:
a) Increased cytoplasmic maturation
b) Decreased cytoplasmic maturation
c) A reduction in cell size
d) Decreased nuclear maturation - Specific (secondary) granules of the neutrophilic granulocyte first appear at which developmental stage?
a) Myeloblast
b) Promyelocyte
c) Myelocyte
d) Metamyelocyte - What are Auer rods, characteristic of some leukemic blasts, composed of?
a) DNA precipitates
b) Fused primary granules
c) Denatured hemoglobin
d) Large cytoplasmic granules - What is the typical life span of a platelet?
a) 5 days
b) 10 days
c) 20 days
d) 30 days - After red blood cells are removed from circulation, hemoglobin is broken down into:
a) Iron, porphyrin, and amino acids
b) Heme, protoporphyrin, and amino acids
c) Iron, heme, and globin
d) Heme, hemosiderin, and globin - Which cytokine is most responsible for eosinophil differentiation and release from the bone marrow?
a) IL-1
b) IL-2
c) IL-4
d) IL-5 - Pluripotent hematopoietic stem cells are capable of producing which of the following?
a) Daughter cells of only one cell line
b) Only T lymphocytes and B lymphocytes
c) Erythropoietin, thrombopoietin, and leukopoietin
d) Lymphoid and myeloid stem cells - Which of the following is a characteristic of cellular changes as megakaryoblasts mature into megakaryocytes?
a) Progressive decrease in overall cell size
b) Increasing basophilia of cytoplasm
c) Nuclear division without cytoplasmic maturation
d) Fusion of the nuclear lobes - What is the most common granulocyte found in normal adult bone marrow?
a) Basophil
b) Myeloblast
c) Eosinophil
d) Metamyelocyte - Which of the following is the largest cell typically found in the bone marrow?
a) Histiocyte
b) Megakaryocyte
c) Osteoblast
d) Mast cell - Von Willebrand factor antigen is synthesized in which of the following cells?
a) Myeloblasts
b) Monoblasts
c) Lymphoblasts
d) Megakaryocytes - The Donath-Landsteiner antibody is characterized as a(n):
a) IgM cold agglutinin
b) Biphasic IgM hemolysin
c) IgG biphasic hemolysin
d) IgG warm agglutinin - In a normal bone marrow aspirate, how many megakaryocytes should be found on average per low-power field (10x)?
a) 1-2
b) 5-10
c) 15-20
d) 25-30 - The abnormal erythrocyte known as a spherocyte may result from a deficiency in:
a) Plasma lipoproteins
b) Cellular membrane proteins
c) Cellular enzymes
d) The cellular lipid bilayer - Which hemoglobin chain’s production is represented by a curve that increases significantly after the 30th week of gestation?
a) Alpha
b) Beta
c) Gamma
d) Delta - Q240. Which organ is the primary site of hematopoiesis in adults?
a) Liver
b) Spleen
c) Bone marrow
d) Thymus - Which growth factor primarily stimulates red blood cell production?
a) Thrombopoietin
b) Erythropoietin
c) Interleukin-6
d) Granulocyte colony-stimulating factor - What is the average lifespan of a normal red blood cell?
a) 60 days
b) 90 days
c) 120 days
d) 150 days - Which white blood cell type is most abundant in normal peripheral blood?
a) Neutrophils
b) Lymphocytes
c) Monocytes
d) Eosinophils - Hemoglobin is primarily responsible for transporting which molecule?
a) Carbon dioxide
b) Oxygen
c) Nitrogen
d) Glucose - What is the normal reference range of platelets in adults?
a) 50–100 × 10⁹/L
b) 100–150 × 10⁹/L
c) 150–450 × 10⁹/L
d) 450–600 × 10⁹/L - Which white blood cell functions as the first line of defense against bacterial infections?
a) Lymphocyte
b) Neutrophil
c) Monocyte
d) Basophil - Which hemoglobin chain is absent in normal adult hemoglobin (HbA)?
a) Alpha
b) Beta
c) Gamma
d) Delta - What is the main function of platelets?
a) Oxygen transport
b) Phagocytosis
c) Hemostasis
d) Antibody production - Which organ is primarily responsible for removing senescent red blood cells?
a) Kidney
b) Liver
c) Spleen
d) Bone marrow - What percentage of circulating leukocytes are typically neutrophils in healthy adults?
a) 10–20%
b) 20–40%
c) 40–60%
d) 70–90% - Which enzyme protects red blood cells from oxidative damage?
a) Amylase
b) Catalase
c) Glucose-6-phosphate dehydrogenase (G6PD)
d) Lipase - Which organ produces erythropoietin in response to hypoxia?
a) Liver
b) Kidney
c) Spleen
d) Pancreas - Which type of white blood cell is increased in allergic reactions and parasitic infections?
a) Eosinophils
b) Basophils
c) Neutrophils
d) Monocytes - Which hemoglobin type is predominant in normal adults?
a) HbA (α₂β₂)
b) HbA₂ (α₂δ₂)
c) HbF (α₂γ₂)
d) HbS - Which structure in hemoglobin binds oxygen?
a) Globin chain
b) Iron in the heme group
c) Heme porphyrin ring
d) 2,3-BPG - What is the role of basophils in immune responses?
a) Phagocytosis
b) Antibody production
c) Release of histamine
d) Killing of parasites - Which stage of red blood cell development is the last nucleated form?
a) Reticulocyte
b) Normoblast
c) Pronormoblast
d) Erythrocyte - Platelets are fragments of which precursor cell?
a) Myeloblast
b) Megakaryocyte
c) Proerythroblast
d) Monoblast - Which immunoglobulin is most associated with allergic reactions mediated by basophils and mast cells?
a) IgA
b) IgE
c) IgG
d) IgM - Which factor increases the oxygen affinity of hemoglobin?
a) Increased 2,3-BPG
b) Increased pH (alkalosis)
c) Increased CO₂
d) Increased temperature - Which WBC matures into a macrophage when it enters tissues?
a) Neutrophil
b) Monocyte
c) Basophil
d) Lymphocyte - The majority of iron in the body is found in:
a) Ferritin
b) Transferrin
c) Hemoglobin
d) Hemosiderin - Which of the following is a primary lymphoid organ?
a) Spleen
b) Lymph nodes
c) Bone marrow
d) Tonsils - Which RBC index measures the average size of red blood cells?
a) MCV
b) MCH
c) MCHC
d) RDW - Which white blood cell is the primary mediator of the adaptive immune response?
a) Neutrophils
b) Lymphocytes
c) Monocytes
d) Basophils - Which platelet granules contain clotting factors and fibrinogen?
a) Alpha granules
b) Dense granules
c) Lysosomal granules
d) Primary granules - Which hemoglobin type is the predominant fetal hemoglobin?
a) HbA
b) HbA₂
c) HbF
d) HbC - Which of the following conditions triggers increased erythropoietin production?
a) Polycythemia vera
b) Hypoxia
c) Iron overload
d) Leukocytosis - Which is the largest type of leukocyte found in normal peripheral blood?
a) Neutrophil
b) Monocyte
c) Eosinophil
d) Lymphocyte
📌 How to Use This Practice Set
- Answer each question before checking the key.
- Focus on why the correct answer is right and the others are wrong.
- Use this set as timed practice to simulate the real exam environment.
Answer Key
Answer Key:
- b) As a constituent of hemoglobin
- c) In the ferrous (Fe²⁺) state
- c) To provide reduced glutathione to prevent hemoglobin oxidation
- d) Removal of imperfect and aging cells
- b) Erythrocytes
- b) Stimulate RNA synthesis of erythroid cells.
- c) Lymphocytes
- d) Granulocytes
- d) Basophils
- b) Inactivating cyclooxygenase, which blocks thromboxane A2 production
- c) Thymus
- d) Methemoglobin
- c) Kill and degranulate bacteria.
- d) DNA
- b) Fe³⁺
- b) Decreased cytoplasmic maturation
- c) Myelocyte
- b) Fused primary granules
- b) 10 days
- c) Iron, heme, and globin
- d) IL-5
- d) Lymphoid and myeloid stem cells
- c) Nuclear division without cytoplasmic maturation
- d) Metamyelocyte
- b) Megakaryocyte
- d) Megakaryocytes
- c) IgG biphasic hemolysin
- a) 1-2
- b) Cellular membrane proteins
- b) Beta
- c) Bone marrow
- b) Erythropoietin
- c) 120 days
- a) Neutrophils
- b) Oxygen
- c) 150–450 × 10⁹/L
- b) Neutrophil
- c) Gamma
- c) Hemostasis
- c) Spleen
- c) 40–60%
- c) Glucose-6-phosphate dehydrogenase (G6PD)
- b) Kidney
- a) Eosinophils
- a) HbA (α₂β₂)
- b) Iron in the heme group
- c) Release of histamine
- b) Normoblast
- b) Megakaryocyte
- b) IgE
- b) Increased pH (alkalosis)
- b) Monocyte
- c) Hemoglobin
- c) Bone marrow
- a) MCV
- b) Lymphocytes
- a) Alpha granules
- c) HbF
- b) Hypoxia
- b) Monocyte
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