Blood groups MCQs With Answer

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Blood groups MCQs With Answer provide a focused, exam-ready review for B.Pharm students preparing in immunohematology and transfusion medicine. This concise introduction covers ABO and Rh systems, antigens, antibodies, serological techniques, and clinical implications such as hemolytic transfusion reactions and hemolytic disease of the newborn. These keyword-rich MCQs emphasize antigen genetics, laboratory typing, crossmatching, weak D/partial D, blood group variants (including Bombay), and drug-induced immune hemolysis to strengthen both theoretical knowledge and practical pharmacology relevance. Ideal for revision, class tests, and competitive exams, the set targets deeper conceptual understanding rather than superficial facts.
Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the biochemical nature of ABO blood group antigens on red blood cells?

  • Protein residues on membrane proteins
  • Lipids in the RBC membrane
  • Carbohydrates on RBC surface
  • Nucleic acid fragments associated with RBCs

Correct Answer: Carbohydrates on RBC surface

Q2. ABO blood group inheritance is best described as which genetic pattern?

  • Simple dominance of A over B
  • Multiple alleles with codominance
  • Polygenic inheritance
  • Sex-linked recessive

Correct Answer: Multiple alleles with codominance

Q3. What is the predominant immunoglobulin class of naturally occurring anti-A and anti-B antibodies in adults?

  • IgA
  • IgM (primarily)
  • IgG (primarily)
  • IgE

Correct Answer: IgM (primarily)

Q4. Which test describes forward grouping in blood typing?

  • Testing patient serum with known RBCs
  • Testing patient RBCs with known antisera
  • Using PCR to detect ABO gene alleles
  • Testing for secretor status in saliva

Correct Answer: Testing patient RBCs with known antisera

Q5. The Bombay (Oh) phenotype is characterized by which feature?

  • Expression of strong A and B antigens
  • Lack of H antigen on RBCs
  • Overexpression of H antigen
  • Only Rh antigens present

Correct Answer: Lack of H antigen on RBCs

Q6. Why is the Rh (D) antigen clinically significant?

  • It determines secretor status
  • It is involved in hemolytic disease of the newborn and transfusion reactions
  • It dictates platelet compatibility only
  • It is irrelevant in transfusion medicine

Correct Answer: It is involved in hemolytic disease of the newborn and transfusion reactions

Q7. Which laboratory method is used to detect weak D expression?

  • Direct agglutination with anti-D at room temperature
  • Heat elution test
  • Indirect antiglobulin (weak D) test
  • DNA sequencing of RHD only

Correct Answer: Indirect antiglobulin (weak D) test

Q8. Which antigen in the Kell system is most immunogenic in transfusion practice?

  • k (Cellano)
  • K (Kell, K1)
  • Kpb
  • Kpc

Correct Answer: K (Kell, K1)

Q9. The Duffy antigen acts as a receptor for which malaria parasite?

  • Plasmodium falciparum
  • Plasmodium malariae
  • Plasmodium vivax
  • Plasmodium ovale

Correct Answer: Plasmodium vivax

Q10. Kidd blood group antibodies (Jka/Jkb) are especially associated with which clinical problem?

  • Immediate hemolytic transfusion reactions only
  • Delayed hemolytic transfusion reactions
  • Purely laboratory artefacts with no clinical significance
  • Platelet refractoriness

Correct Answer: Delayed hemolytic transfusion reactions

Q11. Can a person with Bombay phenotype receive RBCs from a group O donor?

  • Yes, O blood is universally compatible
  • No, only Bombay phenotype blood is compatible
  • Yes, only if crossmatch is negative
  • Yes, if transfused slowly

Correct Answer: No, only Bombay phenotype blood is compatible

Q12. Anti-A,B reagents are primarily useful for which purpose?

  • Distinguishing Rh subtypes
  • Detecting both A and B antigens including weak variants
  • Confirming secretor status
  • Detecting Kell antigens

Correct Answer: Detecting both A and B antigens including weak variants

Q13. An immediate acute hemolytic transfusion reaction is most commonly due to which incompatibility?

  • Kidd antigen mismatch
  • ABO incompatibility
  • Duffy antigen mismatch
  • Kell antigen mismatch

Correct Answer: ABO incompatibility

Q14. What does the Direct Antiglobulin Test (DAT) detect?

  • Free antibodies in patient serum
  • Antibodies or complement bound to patient RBCs
  • Bacterial contamination of blood
  • RBC enzyme deficiencies

Correct Answer: Antibodies or complement bound to patient RBCs

Q15. The Indirect Antiglobulin Test (IAT) is primarily used to detect what?

  • Antibodies or complement on patient RBCs
  • Antibodies in serum/plasma against reagent RBCs
  • Direct hemolysis in vivo
  • Platelet compatibility

Correct Answer: Antibodies in serum/plasma against reagent RBCs

Q16. What is the primary purpose of crossmatching before transfusion?

  • Determine donor blood storage time
  • Detect patient antibodies against donor RBCs to ensure compatibility
  • Measure hemoglobin concentration in donor blood
  • Assess donor platelet count

Correct Answer: Detect patient antibodies against donor RBCs to ensure compatibility

Q17. Secretor status refers to which phenomenon?

  • Presence of H antigen on RBCs
  • Presence of soluble ABH antigens in saliva and secretions
  • Expression of Rh antigens in plasma
  • Production of IgG antibodies against A/B

Correct Answer: Presence of soluble ABH antigens in saliva and secretions

Q18. Which reagent is particularly useful to detect weak A,B phenotypes?

  • Anti-D monoclonal reagent
  • Anti-A,B monoclonal reagent
  • Ulex europaeus lectin
  • Complement reagent

Correct Answer: Anti-A,B monoclonal reagent

Q19. Dolichos biflorus lectin is used to identify which ABO subgroup?

  • A2
  • A1
  • B
  • O

Correct Answer: A1

Q20. Which intervention prevents Rh(D)-mediated hemolytic disease of the newborn?

  • Maternal vaccination against Rh antigen
  • Transfusion of Rh-positive blood to the mother
  • Administering anti-D immunoglobulin to Rh-negative mothers
  • Giving IVIG to the fetus

Correct Answer: Administering anti-D immunoglobulin to Rh-negative mothers

Q21. Anti-D antibodies are primarily of which immunoglobulin class when causing hemolytic disease of the newborn?

  • IgM
  • IgA
  • IgG
  • IgE

Correct Answer: IgG

Q22. Cold agglutinins typically are which immunoglobulin and react at which temperature range?

  • IgG at 37°C
  • IgM at cold temperatures (e.g., 0–4°C)
  • IgA at body temperature
  • IgE at room temperature

Correct Answer: IgM at cold temperatures (e.g., 0–4°C)

Q23. Warm autoantibodies causing autoimmune hemolytic anemia are usually which class?

  • IgM
  • IgG active at 37°C
  • IgA only in neonates
  • Complement components only

Correct Answer: IgG active at 37°C

Q24. Which antibody class is most effective at fixing complement leading to intravascular hemolysis in ABO incompatibility?

  • IgG exclusively
  • IgM
  • IgA
  • IgD

Correct Answer: IgM

Q25. The saline replacement technique is primarily used in serology to resolve which issue?

  • Detect weak D variants
  • Remove rouleaux causing false agglutination
  • Concentrate antibodies for testing
  • Enhance enzyme-treated reactions

Correct Answer: Remove rouleaux causing false agglutination

Q26. Enzyme treatment (e.g., ficin, papain) of RBCs typically enhances reactivity of which antigen systems?

  • Duffy and MNS
  • Rh and Kidd
  • Bombay antigens only
  • Kell antigens only

Correct Answer: Rh and Kidd

Q27. An antibody produced in response to foreign RBC antigens following transfusion is called what?

  • Autoantibody
  • Isoagglutinin
  • Alloantibody
  • HLA antibody

Correct Answer: Alloantibody

Q28. Which of the following antibodies are typically described as “naturally occurring”?

  • Antibodies formed only after transfusion
  • Anti-A and Anti-B in individuals lacking corresponding antigens
  • Anti-D in Rh-negative persons without exposure
  • Drug-dependent antibodies

Correct Answer: Anti-A and Anti-B in individuals lacking corresponding antigens

Q29. Hemagglutination inhibition assays are based on which principle?

  • Enzyme conversion of antigens
  • Soluble antigen preventing visible antigen-antibody agglutination
  • Direct complement fixation on RBCs
  • Heat denaturation of antibodies

Correct Answer: Soluble antigen preventing visible antigen-antibody agglutination

Q30. Which blood group is considered the universal red cell donor for emergency transfusion?

  • AB positive
  • O negative
  • A positive
  • B negative

Correct Answer: O negative

Q31. In Rh incompatibility, why is the first pregnancy usually less affected clinically than subsequent pregnancies?

  • Fetus lacks Rh antigen in first pregnancy
  • Maternal sensitization typically occurs during or after first delivery
  • Maternal IgM crosses placenta in first pregnancy
  • Placental barrier prevents all antibody transfer in first pregnancy

Correct Answer: Maternal sensitization typically occurs during or after first delivery

Q32. Immediate spin crossmatch primarily detects which incompatibility?

  • Minor antigen mismatches like Kidd
  • ABO incompatibility
  • Antibodies requiring antiglobulin phase
  • Platelet-specific antibodies

Correct Answer: ABO incompatibility

Q33. Polyagglutination of RBCs is commonly caused by what mechanism?

  • Exposure of cryptic antigens by bacterial enzymes
  • Inherited absence of H antigen
  • High-titer cold agglutinins only
  • Excess immunoglobulin production by plasma cells

Correct Answer: Exposure of cryptic antigens by bacterial enzymes

Q34. Which commonly used drug class can lead to drug-induced immune hemolytic anemia?

  • Beta-blockers
  • High-dose penicillins and some cephalosporins
  • Proton pump inhibitors
  • Topical antifungals

Correct Answer: High-dose penicillins and some cephalosporins

Q35. The KEL gene encoding Kell antigens is located on which chromosome?

  • Chromosome 1
  • Chromosome 7
  • Chromosome 11
  • Chromosome X

Correct Answer: Chromosome 7

Q36. The genotype associated with Bombay phenotype is conventionally denoted as which of the following?

  • HH or H+
  • hh (homozygous recessive)
  • IAIB heterozygote
  • hh with dominant H

Correct Answer: hh (homozygous recessive)

Q37. Which lectin specifically reacts with the H antigen?

  • Dolichos biflorus
  • Ulex europaeus
  • Peanut agglutinin
  • Wheat germ agglutinin

Correct Answer: Ulex europaeus

Q38. What is the main difference between weak D and partial D phenotypes?

  • Weak D lacks D antigen completely; partial D overexpresses it
  • Weak D has reduced expression of full epitopes; partial D lacks some epitopes and may allo-immunize
  • Both are identical immunologically
  • Partial D is only found in neonates

Correct Answer: Weak D has reduced expression of full epitopes; partial D lacks some epitopes and may allo-immunize

Q39. An electronic crossmatch can be performed under which condition?

  • When antibody screen is negative and records confirm compatibility
  • When DAT is strongly positive
  • Only for platelet transfusions
  • When no patient history is available

Correct Answer: When antibody screen is negative and records confirm compatibility

Q40. A significant storage lesion in packed RBCs that affects oxygen delivery is a decrease in which molecule?

  • Hemoglobin concentration
  • 2,3-DPG (2,3-diphosphoglycerate)
  • Glucose content
  • Albumin in plasma

Correct Answer: 2,3-DPG (2,3-diphosphoglycerate)

Q41. Group O plasma typically contains which antibodies?

  • No antibodies to A or B
  • Anti-A and anti-B antibodies
  • Only anti-D
  • Only anti-Kell

Correct Answer: Anti-A and anti-B antibodies

Q42. Anti-M antibodies are usually of which type and what characteristic may they show?

  • IgG and clinically significant at 37°C
  • IgM, cold-reactive and show dosage
  • IgA and cause severe hemolysis
  • Complement-only reactive

Correct Answer: IgM, cold-reactive and show dosage

Q43. What is the purpose of an elution procedure in immunohematology?

  • Remove plasma antibodies before transfusion
  • Release and identify antibodies bound to RBCs
  • Destroy complement on RBCs
  • Inactivate bacterial contaminants

Correct Answer: Release and identify antibodies bound to RBCs

Q44. An ABO discrepancy due to an A2 subgroup is often caused by what?

  • Production of anti-A1 in the serum of some A2 individuals
  • Complete absence of A antigen
  • Strong expression of B antigen
  • High-titer anti-D antibodies

Correct Answer: Production of anti-A1 in the serum of some A2 individuals

Q45. A positive direct Coombs (DAT) test most likely indicates which condition?

  • Lack of antibodies in serum
  • Autoimmune or alloimmune coating of RBCs
  • Normal RBC membrane stability
  • Platelet dysfunction

Correct Answer: Autoimmune or alloimmune coating of RBCs

Q46. Which immunoglobulin class crosses the placenta and mediates fetal hemolysis?

  • IgM
  • IgG
  • IgA
  • IgD

Correct Answer: IgG

Q47. Hemagglutination tests in blood banking detect reactions based on what observable phenomenon?

  • Color change due to pH
  • Visible clumping of red cells due to antigen-antibody interaction
  • Fluorescence of antibodies
  • Electrical conductivity changes

Correct Answer: Visible clumping of red cells due to antigen-antibody interaction

Q48. Which statement about platelet transfusion and ABO compatibility is correct?

  • ABO compatibility is irrelevant for platelets
  • ABO-compatible platelet transfusion is preferred because donor plasma can cause hemolysis
  • Only Rh compatibility matters for platelets
  • Platelets carry no ABO antigens

Correct Answer: ABO-compatible platelet transfusion is preferred because donor plasma can cause hemolysis

Q49. Individuals who are Duffy negative (Fy[a-b-]) have relative resistance to infection by which organism?

  • Plasmodium falciparum
  • Plasmodium vivax
  • Babesia microti
  • Trypanosoma cruzi

Correct Answer: Plasmodium vivax

Q50. Which reagent is commonly used to differentiate A1 and A2 subgroups?

  • Anti-D
  • Dolichos biflorus lectin (anti-A1)
  • Ulex europaeus
  • Peanut agglutinin

Correct Answer: Dolichos biflorus lectin (anti-A1)

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