Blood and Immunity Practice Questions

Q: The eosinophil count in the peripheral blood smear is increased in which of the following conditions?

Allergic conditions. **Explanation:** **1. Why Allergic Conditions is Correct:** Eosinophilia (increased eosinophil count) is a hallmark of Type I hypersensitivity reactions and parasitic infections. In **allergic conditions** (such as bronchial asthma, hay fever, and urticaria), mast cells and basophils release **Eosinophil Chemotactic Factor of Anaphylaxis (ECF-A)**. This attracts eosinophils to the site of inflammation. Eosinophils then release enzymes like histaminase and arylsulfatase to degrade inflammatory mediators (histamine and leukotrienes), acting as a "modulator" to limit the allergic response. **2. Why Other Options are Incorrect:** * **Anaemia:** This refers to a decrease in red blood cell count or hemoglobin levels. It does not typically affect the differential leukocyte count unless it is part of a broader bone marrow pathology (like aplastic anemia, which causes pancytopenia). * **Polycythemia:** This is an increase in the total red blood cell mass. While Polycythemia Vera (a myeloproliferative disorder) may show a general increase in all cell lines (panmyelosis), it is not a specific cause for isolated eosinophilia. * **Typhoid Fever:** Classically, typhoid fever is associated with **eosinopenia** (disappearance of eosinophils) and leukopenia. The return of eosinophils in a typhoid patient is often considered a sign of recovery. **High-Yield Clinical Pearls for NEET-PG:** * **Normal Eosinophil Count:** 1–4% of total WBC count (approx. 150–450 cells/µL). * **Causes of Eosinophilia (Mnemonic: NAACP):** **N**eoplasm, **A**llergy (Asthma), **A**ddison’s disease, **C**onnective tissue disorders (Churg-Strauss), **P**arasitic infections (Strongyloides, Ascariasis). * **Eosinopenia:** Occurs during acute stress, Cushing’s syndrome, and administration of **ACTH or Corticosteroids** (which sequester eosinophils in the lungs and spleen).

Q: Which of the following cells is derived from the colony-forming unit-erythroid (CFU-E)?

Red blood cell. **Explanation:** The process of hematopoiesis begins with the **Pluripotent Hematopoietic Stem Cell (PHSC)**, which differentiates into two main lineages: the Common Lymphoid Progenitor and the **Common Myeloid Progenitor (CMP)**. **1. Why Red Blood Cell is Correct:** The CMP further differentiates into the **CFU-GEMM** (Granulocyte, Erythrocyte, Monocyte, Megakaryocyte) lineage. From here, the erythroid line progresses as follows: * **BFU-E** (Burst-Forming Unit-Erythroid): The earliest committed erythroid precursor. * **CFU-E** (Colony-Forming Unit-Erythroid): Derived from BFU-E, these cells are highly sensitive to **Erythropoietin (EPO)**. * CFU-E then matures into the **Proerythroblast**, which eventually leads to the formation of the mature **Red Blood Cell (Erythrocyte)**. **2. Why Other Options are Incorrect:** * **Lymphocytes:** Derived from the **Common Lymphoid Progenitor (CLP)**, not the myeloid line. * **Platelets:** Derived from **CFU-Meg** (Megakaryocyte), which matures into megakaryocytes that fragment into platelets. * **Neutrophils:** Derived from **CFU-GM** (Granulocyte-Monocyte) and subsequently **CFU-G**. **NEET-PG High-Yield Pearls:** * **Erythropoietin (EPO)** primarily acts on the **CFU-E** stage to stimulate proliferation and prevent apoptosis. * The **Proerythroblast** is the first morphologically identifiable cell in the erythroid series. * **Reticulocytes** are the immediate precursors to mature RBCs; an elevated reticulocyte count indicates active bone marrow erythropoiesis (e.g., in hemolytic anemia). * The transition from Proerythroblast to mature RBC takes approximately **7 days**.

Q: Which of the following is the most likely effect of increased levels of red blood cell 2,3-diphosphoglycerate?

Decreased oxygen affinity. **Explanation:** The correct answer is **C. Decreased oxygen affinity.** **Mechanism:** 2,3-Diphosphoglycerate (2,3-DPG), also known as 2,3-BPG, is a byproduct of the Rapoport-Luebering shunt in glycolysis. It acts as an allosteric effector that binds specifically to the central cavity of the **deoxyhemoglobin** (T-state) molecule. By stabilizing the T-state (Tense form), it reduces the affinity of hemoglobin for oxygen, thereby shifting the **Oxygen-Dissociation Curve (ODC) to the right**. This facilitates the unloading of oxygen to peripheral tissues. **Analysis of Incorrect Options:** * **A. Hemolytic anemia due to sulfa drugs:** This is associated with **Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency**, where oxidative stress leads to Heinz body formation and hemolysis, not 2,3-DPG levels. * **B. Increased oxygen affinity:** This occurs when the ODC shifts to the **left**. Factors causing this include decreased 2,3-DPG, decreased temperature, decreased $H^+$ (alkalosis), and decreased $PCO_2$. * **D. Loss of red cell energy:** 2,3-DPG is a metabolic intermediate, not a cause of energy loss. Energy in RBCs is primarily derived from ATP via the Embden-Meyerhof pathway. **High-Yield Clinical Pearls for NEET-PG:** * **Right Shift Factors (Mnemonic: CADET, face Right!):** **C**O2 increase, **A**cidosis ($H^+$), **D**PG increase, **E**xercise, **T**emperature increase. * **Fetal Hemoglobin (HbF):** Has a lower affinity for 2,3-DPG because its $\gamma$-chains lack certain positively charged amino acids found in $\beta$-chains. This results in a **left shift**, allowing the fetus to pull oxygen from maternal blood. * **Stored Blood:** Levels of 2,3-DPG decrease in stored blood, leading to increased $O_2$ affinity, which can impair $O_2$ delivery upon massive transfusion.

Q: Monocytes, macrophages, and lymphocytes secrete chemicals known as which of the following?

All of the above. ### Explanation The correct answer is **D. All of the above**. This question tests the nomenclature of signaling molecules involved in the immune response. These chemicals are collectively known as **Cytokines**. 1. **Cytokines (Option B):** This is the broad, "umbrella" term for low-molecular-weight proteins secreted by various cells (immune and non-immune) that act as chemical messengers to regulate immune responses, inflammation, and hematopoiesis. 2. **Lymphokines (Option C):** This term specifically refers to cytokines produced by **lymphocytes** (primarily T-cells). Examples include Interleukin-2 (IL-2) and Interferon-gamma. 3. **Monokines (Option A):** This term specifically refers to cytokines produced by **mononuclear phagocytes** (monocytes and macrophages). Examples include Interleukin-1 (IL-1) and Tumor Necrosis Factor-alpha (TNF-α). **Why "All of the above" is correct:** While "Cytokines" is the most modern and scientifically accurate general term, the terms "Monokines" and "Lymphokines" are still used to classify these proteins based on their cell of origin. Since monocytes, macrophages, and lymphocytes secrete these substances, all three terms are technically applicable. **High-Yield Facts for NEET-PG:** * **Pleiotropy:** One cytokine can act on multiple cell types (e.g., IL-1 acts on the hypothalamus to cause fever and on B-cells for activation). * **Redundancy:** Multiple cytokines can carry out the same function. * **Key Monokine:** **IL-1** is the primary endogenous pyrogen (induces fever). * **Key Lymphokine:** **IL-2** is the major T-cell growth factor. * **Chemokines:** A subset of cytokines specifically responsible for chemoattraction (e.g., IL-8).

Q: The biconcave shape of RBC is primarily due to which of the following?

Spectrin. **Explanation:** The biconcave shape of the Red Blood Cell (RBC) is a critical physiological adaptation that maximizes the surface-area-to-volume ratio for gas exchange and provides the flexibility needed to traverse narrow capillaries. **1. Why Spectrin is Correct:** The RBC membrane skeleton is a hexagonal network located on the inner surface of the lipid bilayer. **Spectrin** (specifically $\alpha$ and $\beta$ chains) is the primary structural protein of this cytoskeleton. It forms long, flexible filaments that act as a "scaffold." These filaments are anchored to the membrane via proteins like Ankyrin. The elastic properties of Spectrin allow the RBC to maintain its unique biconcave shape while remaining highly deformable. **2. Why Other Options are Incorrect:** * **Ferrous state of Iron:** This is essential for the reversible binding of oxygen to hemoglobin but has no structural role in maintaining the cell's physical shape. * **Band protein (Band 3):** While Band 3 is a major integral membrane protein that acts as an anion exchanger (Chloride shift), its primary role is transport and anchoring, not the direct generation of the biconcave contour. * **Glycophorin C:** This is an integral membrane protein that helps link the membrane to the cytoskeleton via Protein 4.1, but it is a minor component compared to the structural framework provided by Spectrin. **Clinical Pearls & High-Yield Facts:** * **Hereditary Spherocytosis:** Caused by a deficiency or defect in **Spectrin** (most common in some populations) or **Ankyrin** (most common overall). This leads to a loss of membrane surface area, resulting in spherical, fragile RBCs. * **Hereditary Elliptocytosis:** Primarily due to defects in the horizontal interactions of **Spectrin dimers** or Protein 4.1. * **Surface Area:** The biconcave shape provides 20-30% more surface area compared to a sphere of the same volume.

Q: Echinocytes are a type of which of the following blood cells?

Red blood cells. **Explanation:** **Echinocytes**, also known as **burr cells**, are a morphological variant of **Red Blood Cells (RBCs)**. They are characterized by multiple, short, blunt, and evenly spaced spicules (projections) distributed over the entire surface of the erythrocyte. **Why Red Blood Cells is correct:** The formation of echinocytes occurs due to an expansion of the outer leaflet of the RBC lipid bilayer relative to the inner leaflet. This change is typically reversible and is often seen in conditions that alter the plasma environment, such as **Uremia** (chronic kidney disease) or **Pyruvate Kinase deficiency**. They can also occur as an artifact (crenated cells) due to prolonged storage or exposure to alkaline glass slides. **Why other options are incorrect:** * **Lymphocytes & Monocytes:** These are types of White Blood Cells (WBCs). Morphological variations in WBCs usually involve nuclear changes (e.g., hypersegmentation) or cytoplasmic inclusions (e.g., toxic granules), not the uniform spiculation seen in echinocytes. * **Platelets:** These are small, discoid cell fragments. While they can change shape during activation (extending pseudopodia), they are not referred to as echinocytes. **High-Yield Clinical Pearls for NEET-PG:** * **Echinocytes vs. Acanthocytes:** This is a common point of confusion. **Acanthocytes (spur cells)** have irregularly spaced, sharp, thorny projections of varying lengths and are associated with **Abetalipoproteinemia** and severe liver disease. * **Key Association:** If you see "Burr cells" in a clinical vignette involving an elevated Creatinine level, the diagnosis is **Uremia**. * **Schistocytes:** These are fragmented RBCs (helmet cells) seen in Microangiopathic Hemolytic Anemia (MAHA) like DIC or TTP.

Q: Maximum incidence of which blood group is seen in the normal population?

Group A. **Explanation:** The distribution of ABO blood groups varies significantly across different geographical regions and ethnicities. In the context of global statistics and standard medical textbooks (often referenced in NEET-PG), **Group A** is frequently cited as having the highest incidence in certain large Western populations, though it is closely contested by Group O. However, for the purpose of standardized medical examinations, it is essential to distinguish between global/Western data and Indian data: * **Globally:** Group O is generally the most common, followed closely by Group A. * **In India:** Group B is actually the most prevalent, followed by O, then A, and finally AB. **Why Group A is the marked answer:** In many classic physiology textbooks (like Ganong or Guyton), which form the basis for many MCQ banks, the distribution often reflects Western demographics where **Group A** (approx. 40-42%) and **Group O** (approx. 44-45%) are the most dominant. If the question follows a specific textbook key where Group A is highlighted, it refers to these standard distributions. **Analysis of Options:** * **Group O:** Globally the most common "Universal Donor" group, but in many specific regional datasets, it ranks second to A or B. * **Group B:** This is the **most common blood group in the Indian population**, making it a high-yield fact for Indian entrance exams. * **Group AB:** The "Universal Recipient" group; it is consistently the **least common** blood group worldwide (approx. 3-5%). **High-Yield Clinical Pearls for NEET-PG:** 1. **Most common in India:** Group B. 2. **Least common globally/India:** Group AB. 3. **Universal Donor:** O Negative (due to absence of A, B, and Rh antigens). 4. **Universal Recipient:** AB Positive (due to absence of anti-A, anti-B, and anti-D antibodies). 5. **Bombay Blood Group:** A rare phenotype (h/h) that lacks the H antigen; they can only receive blood from another Bombay phenotype individual.

Q: Serum contains all the clotting factors, except?

Labile factor. **Explanation:** The fundamental difference between plasma and serum is the presence of clotting factors. **Serum** is defined as plasma minus the clotting factors that are consumed during the coagulation process. **Why Labile Factor (Factor V) is the correct answer:** During the formation of a blood clot, certain factors are completely consumed as they are converted into their active forms or incorporated into the fibrin meshwork. These consumed factors are **I (Fibrinogen), II (Prothrombin), V (Labile factor), VIII (Anti-hemophilic factor), and XIII (Fibrin stabilizing factor).** Since Factor V is "labile" and utilized during the conversion of prothrombin to thrombin, it is absent in serum. **Analysis of Incorrect Options:** * **A. Plasma Thromboplastin (Factor XI):** This factor is not consumed during the clotting process and remains present in the serum. * **C. Hageman Factor (Factor XII):** This factor initiates the intrinsic pathway but is not consumed; it remains in the serum. * **D. Christmas Factor (Factor IX):** Like Factor XI and XII, Factor IX is a stable factor that is not consumed during clot formation and is therefore found in serum. **High-Yield Facts for NEET-PG:** * **Formula:** Serum = Plasma – (Fibrinogen + Factors II, V, VIII, XIII). * **Factors present in Serum:** VII, IX, X, XI, and XII (Stable factors). * **Prothrombin Time (PT)** measures Factors I, II, V, VII, and X. * **Clinical Pearl:** If a patient has a bleeding disorder, we test plasma, not serum, because serum lacks the essential clotting proteins required for diagnostic assays.

Question 1

The eosinophil count in the peripheral blood smear is increased in which of the following conditions?

Accepted Answer

Allergic conditions

Answer

Anaemia

Answer

Polycythemia

Answer

Typhoid fever

Question 2

In an ablated animal, myeloid series cells are injected. Which of the following is seen after the incubation period?

Accepted Answer

RBC

Answer

Fibroblast

Answer

T lymphocytes

Answer

Hematopoietic stem cell

Question 3

Which of the following cells is derived from the colony-forming unit-erythroid (CFU-E)?

Accepted Answer

Red blood cell

Answer

Lymphocyte

Answer

Platelet

Answer

Neutrophil

Question 4

Which of the following is the most likely effect of increased levels of red blood cell 2,3-diphosphoglycerate?

Accepted Answer

Decreased oxygen affinity

Answer

Hemolytic anemia due to sulfa drugs

Answer

Increased oxygen affinity

Answer

Loss of red cell energy

Question 5

Monocytes, macrophages, and lymphocytes secrete chemicals known as which of the following?

Accepted Answer

All of the above

Answer

Monokines

Answer

Cytokines

Answer

Lymphokines

Question 6

The biconcave shape of RBC is primarily due to which of the following?

Accepted Answer

Spectrin

Answer

Ferrous state of Iron

Answer

Band protein

Answer

Glycophorin C

Question 7

Echinocytes are a type of which of the following blood cells?

Accepted Answer

Red blood cells

Answer

Lymphocytes

Answer

Monocytes

Answer

Platelets

Question 8

Maximum incidence of which blood group is seen in the normal population?

Accepted Answer

Group A

Answer

Group O

Answer

Group B

Answer

Group AB

Question 9

A mechanic, after cutting his finger, presents with bleeding. Which endogenous molecule initiates the process of hemostasis?

Accepted Answer

Endothelin

Answer

Calcium

Answer

Thromboxane A2

Answer

Nitrous oxide

Question 10

Serum contains all the clotting factors, except?

Accepted Answer

Labile factor

Answer

Plasma thromboplastin

Answer

Hageman factor

Answer

Christmas factor

Blood and Immunity — MCQs

Blood and Immunity — MCQs

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