Blood Bank ASCP EXAM questions and
answers 2026\2027 A+ Grade
What type of serological testing does the blood
bank technologist perform when determining the
blood group of a patient?
- correct answer phenotyping
If anti-K reacts 3+ with a donor cell with a
genotype KK and 2+ with a Kk cell, the antibody
is demonstrating:
- correct answer Dosage
Carla expresses the blood group antigens Fya, Fyb, and Xga. James shows expressions of none of these
antigens. What factor(s) may account for the absence of these antigens in James?
- correct answer Gender and Race. The frequency of Duffy antigens Fya and Fyb varies
with race. The Fy(a−b−) phenotype occurs in almost
70% of African Americans and is very rare in whites.
The Xga antigen is X-linked and, therefore, expressed more frequently in women (who may inherit the
antigen from either parent) than in men.
Which of the following statements is true?
A. An individual with the BO genotype is
homozygous for B antigen
B. An individual with the BB genotype is
homozygous for B antigen
C. An individual with the OO genotype is
,heterozygous for O antigen
D. An individual with the AB phenotype is
homozygous for A and B antigens
- correct answer B. An individual with the BB genotype is
homozygous for B antigen
Which genotype is heterozygous for C?
A. DCe/dce
B. DCE/DCE
C. Dce/dce
D. DCE/dCe
- correct answer A. DCe/dce
Which genotype(s) will give rise to the Bombay phenotype?
- correct answer The Bombay phenotype will be expressed only when no H substance is present. The Oh
type is expressed by the genotype hh. Bombays produce naturally occurring anti-H, and their serum
agglutinates group
O red cells in addition to red cells from groups A, B, and AB persons.
Meiosis in cell division is limited to the ova and sperm producing four gametes containing what
complement of DNA?
- correct answer 1N. Meiosis involves two nuclear divisions in succession resulting in four gametocytes
each containing half the number of chromosomes found in somatic cells or 1N.
A cell that is not actively dividing is said to be in:
- correct answer Interphase, The cell is engaged in metabolic activity. Chromosomes are not clearly
discerned; however, nucleoli may be
visible
Which of the following describes the expression of most blood group antigens?
- correct answer Codominant
,What blood type is not possible for an offspring of an AO and BO mating?
- correct answer All are possible
The alleged father of a child in a disputed case of paternity is blood group AB. The mother is group O and
the child is group O. What type of exclusion is this?
- correct answer -Indirect/secondary/second order
An indirect/secondary/second order exclusion occurs when a genetic marker is absent in the child but
should have been transmitted by the alleged father. In this case, either A or B should be present in the
child.
If the frequency of gene Y is 0.4 and the frequency of gene Z is 0.5, one would expect that they should
occur together 0.2 (20%) of the time. In actuality,
they are found together 32% of the time. This is an example of:
- correct answer Linkage disequilibrium.
Linkage disequilibrium is a phenomenon in which alleles situated in close proximity on a chromosome
associate with one another more than would be expected from individual allelic frequencies.
In this type of inheritance, the father carries the trait on his X chromosome. He has no sons with the
trait because he passed his Y chromosome to his sons; however, all his daughters will express the trait.
- correct answer Autosomal Dominant
In the Hardy-Weinberg formula, p2 represents:
- correct answer In the Hardy-Weinberg formula p2 + 2pq + q2, p2 and q2 represent homozygous
expressions and 2pq represents heterozygous expression. This formula is
used in population genetics to determine the frequency of different alleles.
What is the Hardy-Weinberg formula?
- correct answer p2 + 2pq + q2 = 1
Why do IgM antibodies, such as those formed against the ABO antigens, have the ability to directly
agglutinate red blood cells (RBCs) and cause visible agglutination?
- correct answer IgM antibodies are larger molecules and have the ability to bind more antigen
, Which of the following enhancement mediums decreases the zeta potential, allowing antibody and
antigen to come closer together?
- correct answer LISS.
LISS contains a reduced concentration of NaCl (0.2%) and results in a reduction in charged ions within
the ionic cloud, decreasing the zeta potential and facilitating antigen and antibody interaction.
This type of antibody response is analogous to an anamnestic antibody reaction.
- correct answer Secondary.
An anamnestic response is a secondary immune response in which memory lymphocytes respond
rapidly to foreign antigen in producing specific antibody. The antibodies are IgG and are produced
at lower doses of antigen than in the primary response.
Which antibodies to a component of complement are contained in the rabbit polyspecific antihuman
globulin reagent for detection of in vivo sensitization?
- correct answer In the DAT (direct antiglobulin test), rabbit
polyspecific antisera contains both an anti-human IgG component and an antibody against the C3d
component of complement.
Which of the following distinguishes A1 from A2 blood groups?
A. A2 antigen will not react with anti-A, A1 will
react strongly (4+)
B. An A2 person may form anti-A1; an A1 person
will not form anti-A1
C. An A1 person may form anti-A2, an A2 person
will not form anti-A1
D. A2 antigen will not react with anti-A from a nonimmunized donor; A1 will react with any anti-A
- correct answer B. An A2 person may form anti-A1; an A1 person will not form anti-A1
A patient's serum is incompatible with O cells. The patient RBCs give a negative reaction to anti-H lectin.
What is the most likely cause of these results?
- correct answer Bombay is the only ABO phenotype incompatible with O cells. The red cells of a
Bombay show a negative reaction to anti-H because the cells contain no H substance
answers 2026\2027 A+ Grade
What type of serological testing does the blood
bank technologist perform when determining the
blood group of a patient?
- correct answer phenotyping
If anti-K reacts 3+ with a donor cell with a
genotype KK and 2+ with a Kk cell, the antibody
is demonstrating:
- correct answer Dosage
Carla expresses the blood group antigens Fya, Fyb, and Xga. James shows expressions of none of these
antigens. What factor(s) may account for the absence of these antigens in James?
- correct answer Gender and Race. The frequency of Duffy antigens Fya and Fyb varies
with race. The Fy(a−b−) phenotype occurs in almost
70% of African Americans and is very rare in whites.
The Xga antigen is X-linked and, therefore, expressed more frequently in women (who may inherit the
antigen from either parent) than in men.
Which of the following statements is true?
A. An individual with the BO genotype is
homozygous for B antigen
B. An individual with the BB genotype is
homozygous for B antigen
C. An individual with the OO genotype is
,heterozygous for O antigen
D. An individual with the AB phenotype is
homozygous for A and B antigens
- correct answer B. An individual with the BB genotype is
homozygous for B antigen
Which genotype is heterozygous for C?
A. DCe/dce
B. DCE/DCE
C. Dce/dce
D. DCE/dCe
- correct answer A. DCe/dce
Which genotype(s) will give rise to the Bombay phenotype?
- correct answer The Bombay phenotype will be expressed only when no H substance is present. The Oh
type is expressed by the genotype hh. Bombays produce naturally occurring anti-H, and their serum
agglutinates group
O red cells in addition to red cells from groups A, B, and AB persons.
Meiosis in cell division is limited to the ova and sperm producing four gametes containing what
complement of DNA?
- correct answer 1N. Meiosis involves two nuclear divisions in succession resulting in four gametocytes
each containing half the number of chromosomes found in somatic cells or 1N.
A cell that is not actively dividing is said to be in:
- correct answer Interphase, The cell is engaged in metabolic activity. Chromosomes are not clearly
discerned; however, nucleoli may be
visible
Which of the following describes the expression of most blood group antigens?
- correct answer Codominant
,What blood type is not possible for an offspring of an AO and BO mating?
- correct answer All are possible
The alleged father of a child in a disputed case of paternity is blood group AB. The mother is group O and
the child is group O. What type of exclusion is this?
- correct answer -Indirect/secondary/second order
An indirect/secondary/second order exclusion occurs when a genetic marker is absent in the child but
should have been transmitted by the alleged father. In this case, either A or B should be present in the
child.
If the frequency of gene Y is 0.4 and the frequency of gene Z is 0.5, one would expect that they should
occur together 0.2 (20%) of the time. In actuality,
they are found together 32% of the time. This is an example of:
- correct answer Linkage disequilibrium.
Linkage disequilibrium is a phenomenon in which alleles situated in close proximity on a chromosome
associate with one another more than would be expected from individual allelic frequencies.
In this type of inheritance, the father carries the trait on his X chromosome. He has no sons with the
trait because he passed his Y chromosome to his sons; however, all his daughters will express the trait.
- correct answer Autosomal Dominant
In the Hardy-Weinberg formula, p2 represents:
- correct answer In the Hardy-Weinberg formula p2 + 2pq + q2, p2 and q2 represent homozygous
expressions and 2pq represents heterozygous expression. This formula is
used in population genetics to determine the frequency of different alleles.
What is the Hardy-Weinberg formula?
- correct answer p2 + 2pq + q2 = 1
Why do IgM antibodies, such as those formed against the ABO antigens, have the ability to directly
agglutinate red blood cells (RBCs) and cause visible agglutination?
- correct answer IgM antibodies are larger molecules and have the ability to bind more antigen
, Which of the following enhancement mediums decreases the zeta potential, allowing antibody and
antigen to come closer together?
- correct answer LISS.
LISS contains a reduced concentration of NaCl (0.2%) and results in a reduction in charged ions within
the ionic cloud, decreasing the zeta potential and facilitating antigen and antibody interaction.
This type of antibody response is analogous to an anamnestic antibody reaction.
- correct answer Secondary.
An anamnestic response is a secondary immune response in which memory lymphocytes respond
rapidly to foreign antigen in producing specific antibody. The antibodies are IgG and are produced
at lower doses of antigen than in the primary response.
Which antibodies to a component of complement are contained in the rabbit polyspecific antihuman
globulin reagent for detection of in vivo sensitization?
- correct answer In the DAT (direct antiglobulin test), rabbit
polyspecific antisera contains both an anti-human IgG component and an antibody against the C3d
component of complement.
Which of the following distinguishes A1 from A2 blood groups?
A. A2 antigen will not react with anti-A, A1 will
react strongly (4+)
B. An A2 person may form anti-A1; an A1 person
will not form anti-A1
C. An A1 person may form anti-A2, an A2 person
will not form anti-A1
D. A2 antigen will not react with anti-A from a nonimmunized donor; A1 will react with any anti-A
- correct answer B. An A2 person may form anti-A1; an A1 person will not form anti-A1
A patient's serum is incompatible with O cells. The patient RBCs give a negative reaction to anti-H lectin.
What is the most likely cause of these results?
- correct answer Bombay is the only ABO phenotype incompatible with O cells. The red cells of a
Bombay show a negative reaction to anti-H because the cells contain no H substance
