Blood Bank ASCP EXAM| 452 QUESTIONS| WITH
COMPLETE SOLUTIONS
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
What antibodies are formed by a Bombay
individual? Correct Answer: Anti-A, B, and H
Acquired B antigens have been found in: Correct Answer: Group A persons.
Blood is crossmatched on an A positive person with a negative antibody screen. The patient received a
transfusion of A positive RBCs 3 years ago. The donors chosen for crossmatch were A positive.
The crossmatch was run on the Ortho Provue and yielded 3+ incompatibility. How can these results be explained? Correct Answer: The patient is likely an A2 with anti-A1 which is causing reactivity in the crossmatch. A negative antibody screen rules out the possibility of an antibody to a high-frequency antigen, and two
donor units incompatible rules out an antibody to a low-frequency antigen. A patient's red cells forward as group O, serum agglutinates B cells (4+) only. Your next step would be: Correct Answer: Incubate washed red cells with anti-A1 and
anti-A,B for 30 minutes at room temperature.
The strong 4+ reaction in reverse grouping suggests the discrepancy is in forward grouping. Incubating washed red cells at room temperature with anti-A and anti-A,B will enhance reactions.
Which typing results are most likely to occur when a patient has an acquired B antigen?
A. Anti-A 4+, anti-B-3+, A1 cells neg, B cells neg
B. Anti-A 3+, anti-B neg, A1 cells neg, B cells neg
C. Anti-A 4+, anti-B 1+, A1 cells neg, B cells 4+
D. Anti-A 4+, anti-B 4+, A1 cells 2+, B cells neg Correct Answer: C. Anti-A 4+, anti-B 1+, A1 cells neg, B cells 4+
In forward typing, a 1+ reaction with anti-B is
suspicious because of the weak reaction and the normal reverse grouping that appears to be group A. This may be indicative of an acquired antigen. In the case of an acquired B, the reverse grouping is the
same for a group A person. Choice A is indicative of group AB; choice B is indicative of a group
A who may be immunocompromised. Choice D may be
caused by a mistyping or an antibody against antigens on reverse cells.
Which blood group has the least amount of
H antigen? Correct Answer: A1B.
The A1B blood group has the least amount of H antigen. This is due to both A and B epitopes present on red cells compromising the availability of H epitopes. A1B cells will yield weak reactions with anti-H lectin.
Blood groups in order from most to least A antigen: Correct Answer: O, A2, B, A2B, A1, A1B
What type RBCs can be transfused to an A2 person with anti-A1? Correct Answer: A person in need of an RBC transfusion who is an A2 with anti-A1 can be transfused A or O cells because the anti-A1 is typically only reactive at room temperature.
What should be done if all forward and reverse ABO results as well as the autocontrol are positive? Correct Answer: Wash the cells with warm saline, autoadsorb the serum at 4°C.
These results point to a cold autoantibody.
Washing the cells with warm saline may elute the autoantibody, allowing a valid forward type to be performed. The serum should be adsorbed using washed cells until the autocontrol is negative.
Then the adsorbed serum should be used for reverse
typing.
