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All questions of Hematologic System for MCAT Exam

Which of the following is a protein involved in the transport of oxygen in the blood?
  • a)
    Fibrinogen
  • b)
    Albumin
  • c)
    Immunoglobulin
  • d)
    Hemoglobin
Correct answer is option 'D'. Can you explain this answer?

Orion Classes answered
Hemoglobin is the protein responsible for transporting oxygen in the blood. It binds to oxygen in the lungs and releases it to tissues throughout the body. Hemoglobin is primarily found in red blood cells.
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An individual with blood type O- could potentially have which blood antibodies present in their plasma?
  • a)
    Both A and B antibodies
  • b)
    Neither A or B antibodies
  • c)
    B antibodies only
  • d)
    A antibodies only
Correct answer is option 'A'. Can you explain this answer?

Orion Classes answered
An individual with blood type O- could potentially have which blood antibodies present in their plasma?
A.Both A and B antibodies
B.Neither A or B antibodies
C.B antibodies only
D.A antibodies only

Which of the following does not play an active role in the production of red blood cells?
  • a)
    Thymus
  • b)
    Kidney
  • c)
    Bone marrow
  • d)
    Spleen
Correct answer is option 'A'. Can you explain this answer?

Orion Classes answered
  • The bone marrow is the major site of hematopoiesis in adults, and is the home of all precursor cells relating to both white and red blood cells.
  • The spleen is most important as a filter for blood, though it also plays a key role in red cell production during infancy and in situations of disease.
  • The kidney secretes erythropoietin in response to low oxygen levels. This hormone stimulates red blood cell production.
  • The thymus is important for immune cell (white cell) production and maturation, but does not play an active role in the production of red blood cells.

When whole blood is run through a centrifuge, why does plasma separate to the top of the tube, while red blood cells separate to the bottom?
  • a)
    The red cell fraction occupies a greater volume than the plasma fraction
  • b)
    The red cell fraction has a greater mass than the plasma fraction
  • c)
    The components of the red cell fraction are larger than the components of the plasma fraction
  • d)
    The red cell fraction has a greater density than the plasma fraction
Correct answer is option 'D'. Can you explain this answer?

Orion Classes answered
Blood is composed of nearly 50% water by volume. The plasma fraction typically occupies a much larger volume than the red cell fraction.
In whole blood, the components are suspended equally within the fluid. Centrifugation displaces the components by applying a rotational force to the suspension.
Centrifugation separates particles in a suspension on the basis of their density. Red blood cells (iron) is much more dense than other blood components.
The red cell fraction has a greater density than the plasma fraction.

What coagulation factor is common to both the intrinsic and extrinsic pathway?
  • a)
    VII (Proconvertin/ stable factor)
  • b)
    IX (Antihemophilic factor B/ Christmas factor)
  • c)
    X (Stuart-Prower factor)
  • d)
    VIII (Antihemophilic factor
Correct answer is option 'C'. Can you explain this answer?

Orion Classes answered
The coagulation cascade involves a series of enzymatic reactions that lead to the formation of a fibrin clot, which helps in the process of blood coagulation. There are two primary pathways involved: the intrinsic pathway and the extrinsic pathway.
The intrinsic pathway is initiated by factors present within the blood, while the extrinsic pathway is triggered by factors outside the blood. These pathways eventually converge to a common pathway, which leads to the final formation of a fibrin clot.
Factor X, also known as Stuart-Prower factor, is a coagulation factor that plays a crucial role in both the intrinsic and extrinsic pathways. It is activated in each pathway and acts as a common link between them. Once activated, Factor X converts prothrombin to thrombin, which in turn converts fibrinogen to fibrin, resulting in clot formation.

What is the principal component which activates and drives the extrinsic pathway of the coagulation cascade?
  • a)
    Intrinsic pathway activation
  • b)
    Plasmin
  • c)
    Upstream coagulation factors such as factors XII and X
  • d)
    Endothelial cell insult
Correct answer is option 'D'. Can you explain this answer?

Orion Classes answered
The extrinsic pathway of the coagulation cascade is primarily triggered by an endothelial cell insult or tissue factor (TF) exposure. Endothelial cells are the cells that line the blood vessels, and when they are damaged or injured, they release tissue factor (TF), also known as factor III. Tissue factor is a protein that plays a crucial role in initiating the extrinsic pathway.
When endothelial cells are insulted, tissue factor comes into contact with circulating factor VII, which then binds to tissue factor and becomes activated. The activated factor VII, together with tissue factor, forms a complex known as the extrinsic tenase complex. This complex subsequently activates factor X, which is a key step in the coagulation cascade.

What physiological condition would produce a relative increase in hematocrit?
  • a)
    High serum protein concentration
  • b)
    Dehydration
  • c)
    Hemolysis
  • d)
    Iron deficiency
Correct answer is option 'B'. Can you explain this answer?

Orion Classes answered
Hematocrit refers to the percentage of the total blood volume occupied by red blood cells. It is a measure of the concentration of red blood cells in the blood. A relative increase in hematocrit means there is a higher proportion of red blood cells compared to the total blood volume.
Dehydration is a condition characterized by inadequate fluid intake or excessive fluid loss, leading to a decrease in the overall blood volume. In this state, the concentration of red blood cells in the blood remains relatively constant, but the plasma volume decreases. As a result, the proportion of red blood cells in the blood increases, leading to a higher hematocrit value.

How would an increase in bicarbonate (HCO3−) relative to all other molecules in the blood affect the oxygen affinity of hemoglobin and why?
  • a)
    Increase oxygen affinity by directly binding with hemoglobin
  • b)
    Decrease oxygen affinity by binding with free protons
  • c)
    Decrease oxygen affinity by directly binding with hemoglobin
  • d)
    Increase oxygen affinity by binding with free protons
Correct answer is option 'D'. Can you explain this answer?

Orion Classes answered
An increase in bicarbonate (HCO3-) in the blood is typically associated with a decrease in blood pH (acidosis). In an acidic environment, the affinity of hemoglobin for oxygen decreases, causing a rightward shift of the oxygen-hemoglobin dissociation curve. This shift promotes the release of oxygen from hemoglobin, allowing it to be delivered to the tissues.
The increase in bicarbonate indirectly affects the oxygen affinity of hemoglobin by binding with free protons (H+). When bicarbonate combines with protons, it forms carbonic acid (H2CO3), which can then dissociate into carbon dioxide (CO2) and water (H2O). This reaction helps regulate blood pH and maintain acid-base balance.
The binding of free protons by bicarbonate leads to a decrease in the concentration of protons in the blood. This reduction in proton concentration helps to stabilize the deoxygenated form of hemoglobin (T-state), which has a higher affinity for oxygen. As a result, the oxygen affinity of hemoglobin increases, allowing it to bind more readily with oxygen in the lungs and release it to the tissues.
Therefore, the correct answer is D. An increase in bicarbonate relative to all other molecules in the blood would increase the oxygen affinity of hemoglobin by binding with free protons.

In terms of cell lineage, how are red blood cells, macrophages, and B cells each classified?
  • a)
    Red blood cells and macrophages are of myeloid lineage, B cells are of lymphoid lineage
  • b)
    Red blood cells are of myeloid lineage, macrophages and B cells are of lymphoid lineage
  • c)
    Macrophages and B cells are of myeloid lineage, red blood cells are of lymphoid lineage
  • d)
    B cells are of myeloid lineage, red blood cells and macrophages are of lymphoid lineage
Correct answer is option 'A'. Can you explain this answer?

Orion Classes answered
Cell lineage refers to the developmental pathway that cells undergo to reach their mature functional state. In terms of cell lineage, red blood cells and macrophages belong to the myeloid lineage, while B cells belong to the lymphoid lineage.
The myeloid lineage gives rise to various types of blood cells involved in innate immunity, including red blood cells (erythrocytes) and macrophages. Red blood cells are responsible for oxygen transport, while macrophages play a role in phagocytosis and immune defense.
The lymphoid lineage gives rise to cells involved in adaptive immunity, including B cells. B cells are responsible for producing antibodies and are crucial in humoral immune responses.

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