Blood MCQs for NEET, AIIMS, JIPMER, INICET

Blood MCQs Asked in NEET / JEE / AIIMS / JIPMER

NEET 2022 Phase-2

Question: The most important buffer of blood is

1. Phosphate buffer
2. Protein buffer
3. Hemoglobin buffer
4. Bicarbonate buffer

Correct Answer: D (Bicarbonate buffer)

Detailed Explanation:
In extracellular fluid (including plasma), the bicarbonate/carbonic acid system (HCO₃⁻/H₂CO₃) is the principal buffer and contributes ~60–70% of the buffering capacity of blood. The ratio [HCO₃⁻]/[H₂CO₃] = 20:1 at pH 7.4. Hemoglobin is the major intracellular buffer inside RBCs, but the question refers to blood as a whole, and standard textbooks (Guyton, Ganong, Harper) and NCERT state that the bicarbonate buffer is the most important buffer of blood.

NEET 2024

Question: A person with blood group A Rh⁻ can receive the blood transfusion from which of the following types?

1. B Rh⁻
2. AB Rh⁻
3. O Rh⁻
4. A Rh⁻
5. A Rh⁺

Correct Answer: C (O Rh⁻)

Detailed Explanation:
Blood group A can receive from A and O (universal donor). Rh⁻ can only receive from Rh⁻ to avoid anti-D antibody reaction. Hence, O Rh⁻ is safe. AB is universal recipient but Rh⁻ specific. A Rh⁺ would cause Rh incompatibility.

NEET 2021

Question: The chloride shift occurs in response to

1. Entry of Cl⁻ into RBCs during CO₂ transport in tissues
2. Exit of Cl⁻ from RBCs during CO₂ transport in lungs
3. Entry of HCO₃⁻ into RBCs in tissues
4. Exit of HCO₃⁻ from plasma in lungs

Correct Answer: A

Detailed Explanation:
In peripheral tissues, CO₂ enters RBCs → converted to HCO₃⁻ by carbonic anhydrase. To maintain electrical neutrality, HCO₃⁻ diffuses out into plasma and Cl⁻ enters RBCs. This is called the **chloride shift or Hamburger shift**. In lungs, the process reverses: Cl⁻ exits RBCs and HCO₃⁻ re-enters.

NEET 2024 (Latest pattern)

Question: In uncompensated metabolic acidosis, the correct findings are

1. pH ↓, PCO₂ normal, HCO₃⁻ ↓
2. pH ↓, PCO₂ ↑, HCO₃⁻ normal
3. pH ↓, PCO₂ ↓, HCO₃⁻ ↓
4. pH ↑, PCO₂ ↓, HCO₃⁻ normal

Correct Answer: A

Detailed Explanation:
Metabolic acidosis is primarily due to ↓ HCO₃⁻ (e.g. diabetic ketoacidosis, lactic acidosis, renal failure). In the uncompensated stage, respiratory compensation (hyperventilation → ↓ PCO₂) has not yet occurred, so pH ↓, HCO₃⁻ ↓, PCO₂ remains normal. Later, compensation causes ↓ PCO₂ (option C would be compensated metabolic acidosis).

AIIMS 2019 & JEE Advanced-level

Question: The oxygen dissociation curve of hemoglobin shifts to the right in all conditions EXCEPT

1. Increase in 2,3-bisphosphoglycerate (2,3-BPG)
2. Decrease in pH (acidosis)
3. Increase in temperature
4. Presence of fetal hemoglobin (HbF)

Correct Answer: D

Detailed Explanation:
Right shift (decreased O₂ affinity, favours O₂ unloading in tissues) is caused by ↑ 2,3-BPG, ↓ pH (Bohr effect), ↑ temperature, and ↑ CO₂. Fetal hemoglobin (HbF = α₂γ₂) has lower affinity for 2,3-BPG than adult HbA, therefore its oxygen dissociation curve is shifted to the left (higher O₂ affinity), helping the fetus extract oxygen from maternal blood.

NEET 2023

Question: Which anticoagulant is used for coagulation studies (PT, aPTT) in the laboratory because it reversibly binds calcium?

1. EDTA
2. Heparin
3. Sodium citrate
4. Sodium oxalate

Correct Answer: C (Sodium citrate)

Detailed Explanation:
Sodium citrate (3.2% or 3.8%) reversibly chelates Ca²⁺ and is the standard anticoagulant for coagulation studies (Prothrombin Time, aPTT). EDTA irreversibly binds Ca²⁺ and damages platelets → used only for hematology (CBC). Heparin is used in vivo and for arterial blood gas samples. Oxalate is obsolete and causes platelet damage.

NEET 2023

Question: Which of the following clotting factors is NOT synthesised in the liver?

1. Factor II (Prothrombin)
2. Factor VII
3. Factor VIII
4. Factor IX

Correct Answer: C (Factor VIII)

Detailed Explanation:
Factor VIII (anti-hemophilic factor) is primarily synthesised by endothelial cells and megakaryocytes (not hepatocytes). All other vitamin-K dependent factors (II, VII, IX, X) and fibrinogen, factor V, XI, XII, XIII are synthesised in the liver. This is why liver disease causes prolonged PT & aPTT, but Hemophilia A (Factor VIII deficiency) is not corrected by vitamin K.

AIIMS Nov 2018 & NEET-PG

Question: Christmas factor is

1. Factor VII
2. Factor VIII
3. Factor IX
4. Factor X

Correct Answer: C (Factor IX)

Detailed Explanation:
Factor IX is also known as Christmas factor (named after Stephen Christmas, the first patient diagnosed with Hemophilia B). Deficiency of Factor IX causes Hemophilia B (Christmas disease), which is clinically indistinguishable from Hemophilia A (Factor VIII deficiency) but has a different genetic basis (X-linked).

NEET 2021

Question: The extrinsic pathway of coagulation is initiated by

1. Contact with negatively charged surface
2. Tissue thromboplastin (Factor III)
3. Activation of Factor XII
4. Platelet aggregation

Correct Answer: B (Tissue thromboplastin)

Detailed Explanation:
Extrinsic pathway is the faster pathway and is triggered by tissue factor (Factor III) released from damaged tissues → activates Factor VII → VIIa → activates Factor X. This is measured by Prothrombin Time (PT). Intrinsic pathway starts with contact activation of Factor XII on negatively charged surfaces (e.g., glass, collagen) and is measured by aPTT.

NEET 2024

Question: Vitamin K is required for the post-translational modification of which amino acid in clotting factors II, VII, IX and X?

1. Gamma-carboxylation of glutamic acid
2. Phosphorylation of serine
3. Hydroxylation of proline
4. Methylation of lysine

Correct Answer: A

Detailed Explanation:
Vitamin K acts as a cofactor for γ-glutamyl carboxylase enzyme that adds carboxyl groups to glutamic acid residues (Gla residues) in factors II, VII, IX, X, Protein C & S. These γ-carboxyglutamate residues enable Ca²⁺ binding, which is essential for attachment of these factors to phospholipid surfaces during coagulation. Warfarin inhibits vitamin K epoxide reductase → blocks this modification.

NEET 2022 Phase-1

Question: In disseminated intravascular coagulation (DIC), which of the following is characteristically increased?

1. Platelet count
2. Fibrinogen level
3. D-dimer
4. Prothrombin time only

Correct Answer: C (D-dimer)

Detailed Explanation:
DIC is characterised by widespread microvascular thrombosis → consumption of platelets & clotting factors + secondary fibrinolysis. Laboratory hallmarks:
• ↑ D-dimer (specific fibrin degradation product)
• ↓ Platelets, ↓ Fibrinogen, ↓ Factor V & VIII
• ↑ PT, ↑ aPTT, ↑ Thrombin time
D-dimer > 500 ng/mL is highly suggestive of DIC (or PE/DVT).

NEET 2024

Question: Most common type of anemia worldwide is

1. Megaloblastic anemia
2. Iron deficiency anemia
3. Aplastic anemia
4. Sickle cell anemia

Correct Answer: B (Iron deficiency anemia)

Detailed Explanation:
Iron deficiency anemia is the most common anemia globally (WHO data) and in India, affecting >50% of children and pregnant women. Causes: poor dietary intake, hookworm infestation, menorrhagia, malabsorption.

NEET 2023 & AIIMS 2022

Question: Microcytic hypochromic anemia with increased RDW and low serum ferritin is seen in

1. Thalassemia trait
2. Anemia of chronic disease
3. Iron deficiency anemia
4. Sideroblastic anemia

Correct Answer: C (Iron deficiency anemia)

Detailed Explanation:
Classic triad of iron deficiency anemia:
• Microcytic hypochromic (MCV < 80 fL, MCH < 27 pg)
• ↑ RDW (>15%) – anisocytosis
• Serum ferritin < 15 ng/mL (most specific)
In thalassemia trait: RDW normal, ferritin normal/high.

NEET 2022 Phase-2

Question: Peripheral smear showing macro-ovalocytes, hypersegmented neutrophils (>5 lobes) and megaloblastic bone marrow is diagnostic of

1. Iron deficiency anemia
2. Megaloblastic anemia
3. Hemolytic anemia
4. Aplastic anemia

Correct Answer: B (Megaloblastic anemia)

Detailed Explanation:
Hallmark features of megaloblastic anemia (Vit B12/folate deficiency):
• Macro-ovalocytes
• Hypersegmented neutrophils (even one neutrophil with ≥6 lobes is diagnostic)
• Pancytopenia common
• Megaloblastic changes in marrow (nuclear-cytoplasmic asynchrony)

NEET 2022 Phase 1

Question: Which one of the following statements is correct?

1. The tricuspid and the bicuspid valves open due to the pressure exerted by the simultaneous contraction of the atria
2. Blood moves freely from atrium to the ventricle during joint diastole
3. Increased ventricular pressure causes closing of the semilunar valves
4. The atrio-ventricular node (AVN) generates an action potential to stimulate atrial contraction

Correct Answer: B

Detailed Explanation:
During joint diastole (relaxation of atria and ventricles), AV valves (tricuspid, bicuspid) are open, allowing free blood flow from atria to ventricles. AVN transmits impulse from SA node to ventricles, not generates it. Semilunar valves close during ventricular diastole due to low pressure.

NEET-II 2016

Question: Name the blood cells whose reduction in number can cause clotting disorder, leading to excessive loss of blood from the body.

1. Erythrocytes
2. Monocytes
3. Leucocytes
4. Thrombocytes

Correct Answer: D (Thrombocytes)

Detailed Explanation:
Thrombocytes (platelets) initiate primary hemostasis by forming plug and releasing factors for coagulation. Reduction (thrombocytopenia) causes bleeding disorders like purpura or hemophilia-like symptoms.

NEET 2017

Question: Which one of the following plasma proteins is involved in the coagulation of blood?

1. Fibrinogen
2. Serum amylase
3. Globulin
4. Albumin

Correct Answer: A (Fibrinogen)

Detailed Explanation:
Fibrinogen (Factor I) is converted to fibrin by thrombin in the final step of coagulation cascade, forming the clot mesh. Other proteins like globulins are for transport/immunity, albumin for osmosis, amylase for digestion.

NEET 2021 & Repeated in 2024

Question: A 25-year-old African patient presents with painful crises, hemolysis and target cells on peripheral smear. The hemoglobin electrophoresis shows HbS > 80%. The condition is

1. Thalassemia major
2. Sickle cell anemia (HbSS)
3. HbSC disease
4. Sickle cell trait (HbAS)

Correct Answer: B (Sickle cell anemia – HbSS)

Detailed Explanation:
Sickle cell anemia = homozygous HbSS (point mutation Glu6Val in β-globin).
Clinical: vaso-occlusive crises, hemolysis, dactylitis, autosplenectomy.
Smear: sickle cells, target cells, Howell-Jolly bodies.
Hb electrophoresis: HbS 80–95%, HbF 5–15%, HbA2 normal, HbA absent.

NEET 2022 Phase 2

Question: Arrange the following formed elements in the decreasing order of their abundance in blood in humans: (a) Platelets (b) Neutrophils (c) Erythrocytes (d) Eosinophils (e) Monocytes

1. (a), (c), (b), (d), (e)
2. (c), (a), (b), (e), (d)
3. (c), (b), (a), (e), (d)
4. (d), (e), (b), (a), (c)

Correct Answer: C

Detailed Explanation:
Abundance: Erythrocytes (RBCs) > Neutrophils (60-70% WBC) > Platelets (1.5-4 lakh/μL) > Monocytes (6-8%) > Eosinophils (2-4%). RBCs are most abundant formed elements.

AIIMS 2019

Question: In beta thalassemia trait, which of the following is characteristically normal?

1. MCV
2. RDW
3. Serum ferritin
4. Hemoglobin electrophoresis

Correct Answer: B (RDW)

Detailed Explanation:
Beta thalassemia trait: Microcytic (↓ MCV), normal RDW (uniform small cells), normal/high ferritin, HbA2 ↑ on electrophoresis. RDW ↑ in iron deficiency.

AIIMS Nov 2018

Question: A patient with microcytic hypochromic anemia, normal RDW, and high serum ferritin likely has:

1. Iron deficiency anemia
2. Anemia of chronic disease
3. Beta thalassemia trait
4. Sideroblastic anemia

Correct Answer: C (Beta thalassemia trait)

Detailed Explanation:
Thalassemia trait: Microcytic hypochromic, normal RDW, normal/high ferritin (no iron loss). Iron deficiency: ↑ RDW, low ferritin. Chronic disease: Normal/low RDW, high ferritin.

JIPMER 2022

Question: The extrinsic pathway of blood coagulation is activated by:

1. Factor XII
2. Tissue factor (Factor III)
3. Platelet activation
4. Thrombin

Correct Answer: B (Tissue factor)

Detailed Explanation:
Extrinsic pathway: Tissue factor (from damaged endothelium) + Factor VII → activates Factor X. Measured by PT. Intrinsic: Factor XII (contact). Common: Factor X onwards.

JIPMER 2021

Question: Which vitamin is essential for gamma-carboxylation of glutamic acid residues in clotting factors II, VII, IX, and X?

1. Vitamin C
2. Vitamin K
3. Vitamin B12
4. Vitamin D

Correct Answer: B (Vitamin K)

Detailed Explanation:
Vitamin K-dependent gamma-carboxylation allows Ca²⁺ binding for phospholipid interaction in coagulation. Deficiency prolongs PT. Warfarin inhibits vitamin K recycling.

NEET 2023

Question: In megaloblastic anemia, peripheral smear typically shows:

1. Microcytes and hypochromia
2. Macro-ovalocytes and hypersegmented neutrophils
3. Sickle cells and target cells
4. Ring sideroblasts

Correct Answer: B

Detailed Explanation:
Due to B12/folate deficiency impairing DNA synthesis: Macro-ovalocytes (↑ MCV), hypersegmented PMNs (>5 lobes). Bone marrow: Megaloblastic changes.

NEET-PG 2023 & INICET

Question: Anemia with normal or increased serum iron, normal/high ferritin, low TIBC and ring sideroblasts in bone marrow is diagnostic of

1. Iron deficiency anemia
2. Anemia of chronic disease
3. Sideroblastic anemia
4. Thalassemia

Correct Answer: C (Sideroblastic anemia)

Detailed Explanation:
Sideroblastic anemia (congenital or acquired – lead poisoning, alcohol, MDS):
• Defective heme synthesis → iron trapped in mitochondria → ring sideroblasts (Prussian blue stain)
• Serum iron ↑, Ferritin ↑, TIBC ↓ (opposite of iron deficiency)
• Pappenheimer bodies & basophilic stippling (in lead poisoning)

Must Read: Comprehensive Notes on Blood for NEET, AIIMS, JIPMER, INICET