Blood and Immunity Practice Questions

Q: Which of the following is also known as Factor X?

Stuart-Prower factor. **Explanation:** Coagulation factors are proteins in the blood that control bleeding through a complex cascade. **Factor X (Stuart-Prower factor)** is a critical high-yield component of this cascade because it marks the beginning of the **Common Pathway**. It is a serine protease that, once activated (Xa), complexes with Factor Va, calcium, and phospholipids to form the *prothrombinase complex*, which converts prothrombin to thrombin. **Analysis of Options:** * **Stuart-Prower factor (Factor X):** Named after the two patients (Mr. Stuart and Miss Prower) in whom the deficiency was first described. It is vitamin K-dependent and synthesized in the liver. * **Hageman factor (Factor XII):** This is the first factor of the **Intrinsic Pathway**. It is activated by contact with negatively charged surfaces like collagen or glass. * **Christmas factor (Factor IX):** A vitamin K-dependent factor in the intrinsic pathway. Its deficiency leads to **Hemophilia B** (Christmas disease). * **Tissue factor (Factor III):** Also known as thromboplastin, it is the primary initiator of the **Extrinsic Pathway** following vascular injury. **High-Yield Clinical Pearls for NEET-PG:** * **Vitamin K-dependent factors:** II, VII, IX, and X (Mnemonic: "1972"). * **Common Pathway Factors:** X, V, II (Prothrombin), and I (Fibrinogen). * **Lab Correlation:** Factor X activity is assessed by both PT (Prothrombin Time) and aPTT (activated Partial Thromboplastin Time) because it sits at the junction of both pathways. * **Direct Factor Xa Inhibitors:** Drugs like **Rivaroxaban** and **Apixaban** are increasingly tested as modern anticoagulants.

Q: The rate of iron uptake is regulated by which one of the following?

Mucosal cell iron stores. **Explanation:** The regulation of iron absorption is a tightly controlled physiological process because the human body lacks an active mechanism for iron excretion. **Why Option A is Correct:** The rate of iron uptake is primarily regulated by the **Mucosal Block Theory**. Iron absorption occurs in the duodenum and upper jejunum. When body iron stores are high, the liver produces **Hepcidin**, the master regulator of iron homeostasis. Hepcidin binds to and degrades **ferroportin** (the efflux channel on the basolateral membrane of enterocytes), trapping iron within the mucosal cells as **ferritin**. When these mucosal cells are shed (desquamated) into the gut lumen, the trapped iron is lost. Conversely, in iron deficiency, hepcidin levels are low, allowing ferroportin to transport iron into the portal circulation. Thus, the iron status of the mucosal cell directly dictates the rate of absorption. **Why Other Options are Incorrect:** * **B & C (Route and Preparation):** While the route (oral vs. IV) and the chemical form (Ferrous vs. Ferric) affect the *amount* and *speed* of iron delivered to the blood, they do not "regulate" the physiological uptake mechanism of the body. * **D (Age):** While iron requirements vary with age (e.g., infants and pregnant women need more), age itself is not the regulatory trigger for the cellular uptake mechanism. **High-Yield NEET-PG Pearls:** * **Hepcidin:** An acute-phase reactant; levels increase during inflammation, leading to "Anemia of Chronic Disease." * **Vitamin C:** Enhances iron absorption by reducing Ferric ($Fe^{3+}$) to the more soluble Ferrous ($Fe^{2+}$) state. * **DMT-1:** The transporter responsible for the uptake of non-heme iron into the enterocyte. * **Toxicity:** Acute iron poisoning is treated with **Deferoxamine** (IV) or **Deferiprone/Deferasirox** (Oral).

Q: Which antigen is lacking in an Rh-negative person?

D. **Explanation:** The Rh blood group system is the second most important system in transfusion medicine. It is based on the presence or absence of specific proteins (antigens) on the surface of red blood cells. **Why Option B is Correct:** The Rh status of an individual (Rh-positive or Rh-negative) is determined specifically by the presence or absence of the **D antigen**. The D antigen is the most immunogenic of all non-ABO antigens. Therefore, an **Rh-negative** person is defined by the complete absence of the D antigen on their erythrocyte membrane. **Analysis of Incorrect Options:** * **Options A and D (C and E):** These are other major antigens within the Rh system (C, c, E, e). While they are part of the Fisher-Race nomenclature, they do not determine whether a person is clinically classified as "Rh-positive" or "Rh-negative." * **Option C (d):** In medical genetics, "d" is a notation used to indicate the **absence** of the D antigen. There is no actual "d antigen" or "d protein." It is a hypothetical designation used to denote the D-negative phenotype. **High-Yield Clinical Pearls for NEET-PG:** * **Immunogenicity:** The D antigen is highly antigenic. If an Rh-negative individual is exposed to Rh-positive blood (via transfusion or pregnancy), they will develop anti-D antibodies (isoimmunization). * **Erythroblastosis Fetalis:** This occurs when an Rh-negative mother carries an Rh-positive fetus. The mother’s anti-D antibodies (IgG) cross the placenta and attack fetal RBCs. * **Prophylaxis:** Anti-D immunoglobulin (RhoGAM) is administered to Rh-negative mothers to prevent sensitization. * **Inheritance:** The Rh system is governed by two closely linked genes on **Chromosome 1**: *RHD* and *RHCE*.

Q: Which type of haemoglobin is alkali resistant?

HbF. **Explanation:** The correct answer is **HbF (Fetal Haemoglobin)**. **Why HbF is Alkali Resistant:** The resistance of haemoglobin to denaturation by strong alkaline solutions (like Potassium Hydroxide) is known as the **Singer’s Alkali Denaturation Test**. HbF is uniquely resistant to alkali because of its structural composition, specifically the presence of **gamma ($\gamma$) chains**. In an alkaline medium, adult haemoglobin (HbA) denatures and precipitates rapidly, whereas HbF remains stable. This property is clinically utilized to detect the presence of fetal blood in maternal circulation or to diagnose conditions like Thalassemia where HbF levels are elevated. **Analysis of Incorrect Options:** * **HbA ($\alpha_2\beta_2$):** This is the major adult haemoglobin. It is highly sensitive to alkali and denatures within 1–2 minutes when exposed to a high pH. * **HbA2 ($\alpha_2\delta_2$):** A minor adult haemoglobin (normal <3.5%). Like HbA, it lacks gamma chains and is not alkali-resistant. * **HbS:** This is the variant found in Sickle Cell Anemia (glutamate replaced by valine at the 6th position of the $\beta$ chain). It is also sensitive to alkali denaturation. **High-Yield NEET-PG Pearls:** * **Structure:** HbF consists of two alpha ($\alpha$) and two gamma ($\gamma$) chains ($\alpha_2\gamma_2$). * **Oxygen Affinity:** HbF has a **higher affinity for oxygen** than HbA because it binds poorly to 2,3-BPG. This allows the fetus to extract oxygen from maternal blood. * **Apt Test:** A clinical test used to differentiate fetal blood from maternal blood in neonatal gastric aspirate or vaginal bleeding, based on HbF’s alkali resistance. * **Switch:** The transition from HbF to HbA begins at 30 weeks of gestation and is usually complete by 6 months of age.

Q: Which of the following is NOT a Vitamin K dependent clotting factor?

Protein C. **Explanation:** The synthesis of certain coagulation factors in the liver requires **Vitamin K** as a cofactor for the enzyme **gamma-glutamyl carboxylase**. This enzyme adds a carboxyl group to glutamate residues on these proteins, allowing them to bind calcium ions and adhere to phospholipid surfaces—a critical step in the clotting cascade. **Why the answer is Protein C (Note on Question Context):** There appears to be a technical nuance in this question. Traditionally, the **Vitamin K-dependent proteins** include: * **Pro-coagulants:** Factors II (Prothrombin), VII, IX, and X. * **Anti-coagulants:** Protein C, Protein S, and Protein Z. In many standard NEET-PG patterns, if the question asks for "clotting factors" (pro-coagulants) specifically, **Protein C** is the odd one out because it is an **anticoagulant** (it inactivates Factors Va and VIIIa), even though it is Vitamin K-dependent. **Analysis of Options:** * **Factor II (Prothrombin):** A Vitamin K-dependent pro-coagulant. It is the precursor to thrombin. * **Factor IX (Christmas Factor):** A Vitamin K-dependent pro-coagulant involved in the intrinsic pathway. * **Factor X (Stuart-Prower Factor):** A Vitamin K-dependent pro-coagulant that marks the beginning of the common pathway. **High-Yield Clinical Pearls for NEET-PG:** 1. **Mnemonic:** Remember "**2, 7, 9, 10, C, and S**" to recall all Vitamin K-dependent proteins. 2. **Warfarin (Coumadin):** Acts by inhibiting Vitamin K Epoxide Reductase (VKOR). 3. **Warfarin-Induced Skin Necrosis:** Occurs because Protein C has a shorter half-life than the pro-coagulant factors. When starting Warfarin, Protein C levels drop first, creating a transient hypercoagulable state. 4. **PT/INR:** This is the most sensitive lab test to monitor Vitamin K deficiency or Warfarin therapy because **Factor VII** has the shortest half-life among the clotting factors.

Q: Coagulation time of blood is prolonged in which of the following conditions?

Hemophilia. **Explanation:** **1. Why Hemophilia is Correct:** Coagulation Time (CT) measures the time required for blood to clot via the **intrinsic and common pathways**. Hemophilia (specifically Hemophilia A and B) is caused by a deficiency of clotting factors VIII and IX, respectively. These factors are critical components of the intrinsic pathway. In their absence, the formation of fibrin is significantly delayed, leading to a **prolonged Coagulation Time**. Notably, the Bleeding Time (BT) in Hemophilia remains normal because platelet function and primary hemostasis are unaffected. **2. Why the Other Options are Incorrect:** * **Leukemia:** This is a malignancy of white blood cells. While advanced leukemia can cause thrombocytopenia (low platelets) leading to a prolonged *Bleeding Time*, it does not typically affect the clotting factor cascade directly; therefore, CT remains normal. * **Pernicious Anemia:** This is caused by Vitamin B12 deficiency due to a lack of intrinsic factor. It primarily affects erythropoiesis (causing megaloblastic anemia) and does not involve the coagulation cascade. * **Malignant Neutropenia (Agranulocytosis):** This is a severe reduction in neutrophil count, making the patient highly susceptible to infections. It has no physiological impact on the blood's ability to clot. **Clinical Pearls for NEET-PG:** * **Bleeding Time (BT):** Reflects platelet function and vascular integrity. Prolonged in Thrombocytopenia and von Willebrand Disease. * **Coagulation Time (CT):** Reflects the intrinsic pathway. Prolonged in Hemophilia and during Heparin therapy. * **Prothrombin Time (PT):** Reflects the extrinsic pathway (Factor VII). Prolonged in Vitamin K deficiency and Warfarin therapy. * **Vitamin K Deficiency:** Prolongs both PT and CT because it affects factors II, VII, IX, and X.

Q: Which of the following is NOT a function of blood plasma?

Transport of oxygen. ### Explanation **1. Why "Transport of Oxygen" is the Correct Answer:** While a very small amount of oxygen (about 1.5% or 0.3 ml/dL) is dissolved physically in the plasma, the **primary and functional transport of oxygen** is the responsibility of **Hemoglobin** located within **Red Blood Cells (RBCs)**. In the context of physiological functions, oxygen transport is categorized as a cellular function rather than a plasma function. Plasma's role in gas transport is primarily focused on Carbon Dioxide (as bicarbonate ions). **2. Analysis of Incorrect Options:** * **A. Transport of Hormones:** Plasma serves as the primary vehicle for hormones. Water-soluble hormones (e.g., Catecholamines) travel freely, while lipid-soluble hormones (e.g., Steroids, Thyroid hormones) travel bound to specific plasma proteins like Albumin or Globulins. * **C. Transport of Antibodies:** Antibodies (Immunoglobulins) are specialized proteins synthesized by plasma cells and are found exclusively in the **gamma-globulin fraction** of the blood plasma. * **D. Transport of Chylomicrons:** After digestion, dietary lipids are packaged into chylomicrons by enterocytes. These enter the bloodstream via the thoracic duct and are transported through the plasma to reach the liver and adipose tissue. **3. NEET-PG High-Yield Pearls:** * **Plasma vs. Serum:** Plasma contains clotting factors (like Fibrinogen); Serum is Plasma minus the clotting factors. * **Oncotic Pressure:** Plasma proteins (mainly **Albumin**) maintain the Colloid Osmotic Pressure (~25-28 mmHg), which prevents edema. * **Buffering:** Plasma proteins act as an important blood buffer system due to their amphoteric nature (Zwitterions). * **Specific Gravity:** The specific gravity of plasma is approximately **1.022 to 1.026**, primarily determined by the concentration of plasma proteins.

Q: Which of the following cells increases in case of parasitic infection?

Eosinophils. ### Explanation **Correct Answer: C. Eosinophils** **Mechanism and Concept:** Eosinophils are specialized granulocytes primarily responsible for combating multicellular parasites, such as helminths (worms). When a parasitic infection occurs, eosinophils undergo **degranulation**, releasing highly potent cytotoxic proteins stored in their large acidophilic granules. The most significant of these is **Major Basic Protein (MBP)**, which is directly toxic to the parasite's tegument (outer coating). They also release Eosinophil Cationic Protein (ECP) and peroxidase to destroy the pathogen. **Analysis of Incorrect Options:** * **A. Neutrophils:** These are the "first responders" and the primary cell type in **acute bacterial infections** and pyogenic inflammation. They utilize phagocytosis and respiratory burst to kill bacteria. * **B. Basophils:** These cells are primarily involved in **allergic reactions** and type I hypersensitivity. They contain histamine and heparin; while they share a common lineage with eosinophils, they are not the primary responders to parasites. * **D. Monocytes:** These are mononuclear cells that migrate into tissues to become **macrophages**. They are typically elevated in **chronic infections** (e.g., Tuberculosis) and are responsible for long-term phagocytosis and antigen presentation. **NEET-PG High-Yield Pearls:** * **Eosinophilia Definition:** Absolute Eosinophil Count (AEC) > 500 cells/µL. * **Common Causes (Mnemonic: NAAACP):** **N**eoplasia, **A**llergy (Asthma/Hay fever), **A**ddison’s disease, **A**theroembolism, **C**onnective tissue disorders, **P**arasites. * **Charcot-Leyden Crystals:** These are microscopic crystals found in the sputum of asthmatics or stool of parasite patients, formed from the breakdown of eosinophil membranes (specifically Galectin-10). * **IL-5:** This is the primary cytokine responsible for the production, activation, and chemotaxis of eosinophils.

Q: All of the following clotting factors are synthesized in the liver except?

Factor III. **Explanation:** The liver is the primary site for the synthesis of almost all coagulation factors. However, **Factor III (Tissue Thromboplastin/Tissue Factor)** is the notable exception. **1. Why Factor III is the correct answer:** Factor III is a high-molecular-weight lipoprotein found in the membranes of various body tissues (such as the brain, lungs, and placenta) and vascular adventitia. It is released into the blood following **vascular injury** or endothelial damage to initiate the extrinsic pathway of coagulation. Since it is a structural component of tissues rather than a circulating plasma protein produced by hepatocytes, it is not synthesized in the liver. **2. Analysis of Incorrect Options:** * **Factor V (Proaccelerin):** Synthesized primarily in the liver. It acts as a cofactor in the prothrombinase complex. * **Factor VII (Stable Factor):** Synthesized in the liver. It is a Vitamin K-dependent factor and the first to decrease in liver disease due to its short half-life. * **Factor IX (Christmas Factor):** Synthesized in the liver. It is a Vitamin K-dependent serine protease involved in the intrinsic pathway. **3. High-Yield Clinical Pearls for NEET-PG:** * **Vitamin K-dependent factors:** II, VII, IX, and X (mnemonic: "1972"), along with Protein C and S. * **Factor VIII Exception:** While most factors are purely hepatic, Factor VIII is synthesized in sinusoidal endothelial cells (not hepatocytes) and extrahepatic sites like the lungs and kidneys. * **Shortest Half-life:** Factor VII (~4–6 hours). This makes the **Prothrombin Time (PT)** the best indicator of acute liver synthetic function. * **Factor IV:** This is simply **Calcium ions**, which are not "synthesized" but are essential for almost all steps of the coagulation cascade.

Question 1

Which of the following is also known as Factor X?

Accepted Answer

Stuart-Prower factor

Answer

Hageman factor

Answer

Christmas factor

Answer

Tissue factor

Question 2

The rate of iron uptake is regulated by which one of the following?

Accepted Answer

Mucosal cell iron stores

Answer

Route of administration

Answer

Preparation administered

Answer

Age of the patient

Question 3

Which antigen is lacking in an Rh-negative person?

Accepted Answer

D

Answer

C

Answer

d

Answer

E

Question 4

Which type of haemoglobin is alkali resistant?

Accepted Answer

HbF

Answer

HbA

Answer

HbA2

Answer

HbS

Question 5

Erythropoietin levels are increased by:

Accepted Answer

Decreased PO2

Answer

Decreased PCO2

Answer

Decreased Hb

Answer

Decreased pH

Question 6

Which of the following is NOT a Vitamin K dependent clotting factor?

Accepted Answer

Protein C

Answer

Factor II

Answer

Factor X

Answer

Factor IX

Question 7

Coagulation time of blood is prolonged in which of the following conditions?

Accepted Answer

Hemophilia

Answer

Leukemia

Answer

Pernicious anaemia

Answer

Malignant neutropenia

Question 8

Which of the following is NOT a function of blood plasma?

Accepted Answer

Transport of oxygen

Answer

Transport of hormones

Answer

Transport of antibodies

Answer

Transport of chylomicrons

Question 9

Which of the following cells increases in case of parasitic infection?

Accepted Answer

Eosinophils

Answer

Neutrophils

Answer

Basophils

Answer

Monocytes

Question 10

All of the following clotting factors are synthesized in the liver except?

Accepted Answer

Factor III

Answer

Factor V

Answer

Factor VII

Answer

Factor IX

Blood and Immunity — MCQs

Blood and Immunity — MCQs

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