1.
Which of the following is not true?
Correct Answer
C. IgG is the best complement fixing immunoglobulin.
Explanation
IgG is not the best complement fixing immunoglobulin. Complement fixation is a process in which antibodies bind to antigens and activate the complement system, leading to the destruction of the target. While IgG can fix complement, IgM is considered the most efficient complement fixing immunoglobulin.
2.
Which of the following domains is considered to be the foot of IgE?
Correct Answer
D. CH4
Explanation
The correct answer is CH4. The foot of IgE is considered to be the CH4 domain.
3.
What type of immunity develops during convalescence from an infection?
Correct Answer
A. Natural active immunity
Explanation
During convalescence from an infection, the body's immune system develops natural active immunity. This means that the immune system produces its own antibodies to fight off the infection. This type of immunity is long-lasting and provides protection against future infections by the same pathogen.
4.
The coating of particulate antigen by antibody and/or complement components that allows them to be more phagocytized readily is called:
Correct Answer
C. Opsonization
Explanation
Opsonization refers to the process in which antibodies and/or complement components coat a particulate antigen, such as a bacterium or a virus, making it more easily recognized and engulfed by phagocytic cells. This coating enhances the phagocytosis of the antigen by immune cells, such as macrophages and neutrophils. Opsonization plays a crucial role in the immune response against pathogens, as it facilitates the efficient removal of these pathogens from the body.
5.
Which of the following is correct?
Correct Answer
D. The C5 convertase in the Classical Pathway of complement activation is C4b2a3b.
Explanation
The C5 convertase in the Classical Pathway of complement activation is C4b2b3b. This means that in the Classical Pathway, the C5 convertase is composed of C4b, C2b, and C3b. These components come together to form the C5 convertase enzyme, which is responsible for cleaving C5 into C5a and C5b. This is an important step in the complement cascade, as it leads to the formation of the membrane attack complex and the destruction of target cells.
6.
Which of the following plays an important role as an external defense mechanism?
Correct Answer
A. pHagocytosis
Explanation
Phagocytosis is a process by which cells engulf and destroy foreign particles, such as bacteria or viruses, as a defense mechanism. It plays an important role in the body's external defense against pathogens. CRP (C-reactive protein), lysozyme, and complement are also involved in the immune response, but they do not directly participate in phagocytosis.
7.
MHC molecules are associated with which of the following?
Correct Answer
D. All of the above
Explanation
MHC molecules are associated with all of the above options. MHC molecules play a crucial role in the immune system by presenting antigens to T cells. This presentation helps in determining whether a graft will be rejected, as MHC molecules help identify foreign tissues. MHC molecules are also involved in autoimmune diseases, as they can present self-antigens, leading to an immune response against the body's own tissues. Additionally, MHC molecules are responsible for determining which agents an individual responds to, as they present antigens to T cells, initiating an immune response. Therefore, all of the given options are correct.
8.
All of the following are characteristic of a good immunogen except
Correct Answer
D. Found on host cells
Explanation
A good immunogen should have internal complexity, a large molecular weight, and the presence of numerous epitopes. However, it should not be found on host cells as this would indicate that the immune system recognizes it as self and would not mount an immune response against it.
9.
Which of the following is characteristic of the endpoint method of RID?
Correct Answer
B. Concentration is directly proportional to the square of the diameter.
Explanation
The correct answer is "Concentration is directly proportional to the square of the diameter." This means that as the concentration of the substance being measured increases, the diameter of the endpoint also increases, and the relationship between concentration and diameter is a direct proportion. This characteristic is specific to the endpoint method of RID.
10.
Agglutination of dyed bacterial cells represents which type of reaction?
Correct Answer
A. Direct agglutination
Explanation
Agglutination of dyed bacterial cells represents direct agglutination. This type of reaction occurs when antibodies directly bind to antigens on the surface of bacterial cells, causing them to clump together or agglutinate. In this case, the bacterial cells are dyed, making it easier to visualize the agglutination reaction.
11.
A positive direct Coombs test would occur under which circumstances?
Correct Answer
D. Any of the above
Explanation
A positive direct Coombs test can occur under any of the given circumstances: hemolytic disease of the newborn, autoimmune hemolytic anemia, or antibodies to drugs that bind to red cells. This test is used to detect antibodies or complement proteins that are bound to the surface of red blood cells, which can lead to their destruction. Therefore, if any of these conditions are present, the test would be positive.
12.
How much diluent needs to be added to 0.2mL of serum to make a 1:20 dilution?
Correct Answer
C. 3.8 mL
Explanation
To make a 1:20 dilution, the total volume (serum + diluent) must be 20 times the volume of serum. Since you have 0.2 mL of serum, the total volume should be 0.2 mL × 20 = 4.0 mL. To determine how much diluent to add, subtract the serum volume from the total volume: 4.0 mL - 0.2 mL = 3.8 mL. Therefore, the answer is 3.8 mL.
13.
All of the following are true of IgM except that it
Correct Answer
A. Can cross the placenta
Explanation
IgM is the first antibody produced during an immune response and is considered a primary response antibody. It is a pentamer structure and contains a J chain, which helps stabilize its structure. IgM is also known to fix complement, which is an important part of the immune response. However, IgM cannot cross the placenta, unlike other antibodies such as IgG.
14.
If cells of an individual are not agglutinated by serum from anyone else, this represents which Lansteiner blood type?
Correct Answer
C. Type O
Explanation
If cells of an individual are not agglutinated by serum from anyone else, this indicates that the individual does not have any antigens on their red blood cells. This is characteristic of Type O blood, which is known as the universal donor because it can be safely transfused to individuals with any other blood type.
15.
Metchnikoff first described which of the following?
Correct Answer
A. pHagocytosis
Explanation
Metchnikoff first described phagocytosis.
16.
The inflammatory process is characterized by all of the following except
Correct Answer
C. Decreased capillary permeability
Explanation
The inflammatory process is characterized by increased blood supply to the area, migration of white blood cells, and the appearance of acute phase reactants. However, decreased capillary permeability is not a characteristic of the inflammatory process.
17.
In an agglutination reaction, if cells are not centrifuged long enough, which of the following might occur?
Correct Answer
A. False-negative result
Explanation
If cells are not centrifuged long enough in an agglutination reaction, the false-negative result might occur. This means that the test would incorrectly indicate that the reaction did not occur or that the substance being tested for is not present, even though it actually is.
18.
The density gradient solution used for the separation of lymphocytes
Correct Answer
B. Ficolle medium
Explanation
Ficolle medium is a density gradient solution commonly used for the separation of lymphocytes. It is a mixture of colloidal silica particles and a polysaccharide called ficoll. When a sample containing lymphocytes is layered on top of the Ficolle medium and centrifuged, the lymphocytes will migrate to a specific region in the density gradient based on their density. This allows for the isolation and purification of lymphocytes from other cell types in the sample.
19.
The purpose of serum inactivation is/are
Correct Answer
D. All of the above
Explanation
Serum inactivation serves multiple purposes. It destroys the native complement, removes heat-labile anti-complementary substances, and stabilizes the serologic properties of the serum. Therefore, the correct answer is "all of the above."
20.
Inactivation of serum is done by heating at ____ for ____.
Correct Answer
A. 56 degrees Celsius, 30 minutes
21.
Which of the following reagents is used to cleave a polymeric antibody at the J chain resulting in monomers?
Correct Answer
D. Dithiothreitol
Explanation
Dithiothreitol is used to cleave a polymeric antibody at the J chain resulting in monomers. Dithiothreitol is a reducing agent that breaks disulfide bonds, which are important for maintaining the structure of the antibody. By cleaving the J chain, the polymeric antibody is broken down into individual monomers.
22.
Diabetes mellitus can be detected by typing HLA of class
Correct Answer
B. II
Explanation
HLA typing refers to the process of determining the specific human leukocyte antigen (HLA) alleles present in an individual. HLA class II typing is particularly useful for detecting certain autoimmune diseases, including type 1 diabetes mellitus. This is because certain HLA class II alleles, such as HLA-DR3 and HLA-DR4, are strongly associated with an increased risk of developing type 1 diabetes. Therefore, by typing the HLA class II alleles, it is possible to identify individuals who may be at a higher risk for developing diabetes mellitus.
23.
The exact binding site of an antigen is called its
Correct Answer
A. Epitope.
Explanation
The correct answer is epitope. An epitope is the specific part of an antigen that binds to an antibody or a receptor on a T cell. It is also known as an antigenic determinant. The paratope, on the other hand, is the specific part of an antibody or a T cell receptor that binds to the epitope. Valence refers to the number of antigen-binding sites on an antibody molecule. Therefore, the correct answer is epitope, as it specifically refers to the binding site of an antigen.
24.
Which of the following is true about RPR and VDRL?
Correct Answer
D. These are non-specific for sypHilis.
Explanation
RPR (Rapid Plasma Reagin) and VDRL (Venereal Disease Research Laboratory) tests are both used to detect antibodies in the blood that are associated with syphilis. However, these tests are not specific for syphilis and can also be positive in other conditions such as autoimmune diseases, certain infections, and pregnancy. Therefore, the statement "These are non-specific for syphilis" is true.
25.
Skin, lactic acid secretions, stomach acidity, and the motion of cilia represent which type of immunity?
Correct Answer
A. Natural
Explanation
Skin, lactic acid secretions, stomach acidity, and the motion of cilia are all natural defense mechanisms of the body. These mechanisms provide a non-specific, innate form of immunity that helps protect the body from pathogens and foreign substances. This type of immunity is known as natural immunity. It is present from birth and does not require prior exposure to specific pathogens.
26.
Which of the following is a primary lymphoid organ?
Correct Answer
C. Thymus
Explanation
The thymus is a primary lymphoid organ because it is responsible for the development and maturation of T cells, a type of white blood cell involved in the immune response. The thymus is where T cells undergo selection and differentiation, acquiring the ability to recognize and respond to specific antigens. This process is crucial for the proper functioning of the immune system. Lymph nodes, spleen, and mucosal associated lymphoid tissue are secondary lymphoid organs, where immune responses are initiated and carried out.
27.
Which of the following antigens are found on the T cell subset known as "inducers"?
Correct Answer
B. CD4
Explanation
CD4 antigens are found on the T cell subset known as "inducers". CD4 is a glycoprotein that is expressed on the surface of helper T cells, which play a crucial role in activating and coordinating immune responses. CD4 helper T cells recognize and bind to antigens presented by antigen-presenting cells, initiating the immune response. CD3, CD8, and CD11 are antigens found on other T cell subsets, but not specifically on inducers.
28.
Which of the following are found on a mature B cell?
Correct Answer
B. IgM and IgD
Explanation
IgM and IgD are both types of immunoglobulins (antibodies) that are found on mature B cells. These antibodies play a crucial role in the immune response by recognizing and binding to specific antigens. The presence of IgM and IgD on B cells allows them to respond to a wide range of pathogens and initiate an immune response. The other options listed (IgG and IGD, alpha and beta chains, CD3 and CD4) are not typically found on mature B cells.
29.
Bence Jones proteins are identical
Correct Answer
C. L chains
Explanation
Bence Jones proteins are monoclonal immunoglobulin light chains, specifically either kappa or lambda chains. They are produced by abnormal plasma cells and are often found in the urine of patients with multiple myeloma. Therefore, the correct answer is L chains.
30.
a 4% solution of RBC is needed for diagnostic testing in the laboratory. What dilution of packed red blood cells does this represent?
Correct Answer
A. 1:25
Explanation
A 4% solution of RBC means that there is 4 grams of RBC in 100 mL of solution. To find the dilution, we need to compare this concentration to the concentration of the packed red blood cells. Since the answer is 1:25, it means that 1 part of packed red blood cells is diluted with 25 parts of solution. This dilution ratio allows for the desired 4% concentration of RBC in the final solution.
31.
The most specific cells containing antigens that agglutinate with heterophile antibodies are
Correct Answer
C. Sheep erythrocytes
Explanation
Sheep erythrocytes are the most specific cells that agglutinate with heterophile antibodies. This means that when heterophile antibodies are present, they will specifically bind to antigens on sheep erythrocytes, causing them to clump together or agglutinate. Human and horse erythrocytes may also agglutinate with heterophile antibodies, but sheep erythrocytes are the most specific and reliable indicator of their presence. Therefore, the correct answer is sheep erythrocytes.
32.
IgG is sometimes referred to as an incomplete antibody because
Correct Answer
B. It may be to small to produce lattice formation.
Explanation
IgG is sometimes referred to as an incomplete antibody because it may be too small to produce lattice formation. Lattice formation refers to the clumping of antigens and antibodies together, which is important for certain immune responses such as agglutination. IgG, being a smaller antibody, may not have enough size or structure to effectively form lattices and clump antigens. This can affect its ability to carry out certain immune functions.
33.
What is the immune mechanism involved in Type III hypersensitivity reaction?
Correct Answer
A. Cellular antigens are involved.
Explanation
Type III hypersensitivity reactions involve the formation of immune complexes, which are made up of antigens and antibodies. These immune complexes can then deposit in various tissues, leading to inflammation and tissue damage. In this type of reaction, cellular antigens are involved, meaning that the immune complexes are formed with antigens that are present on the surface of cells. This immune mechanism is responsible for the pathogenesis of diseases such as systemic lupus erythematosus and rheumatoid arthritis.
34.
Which of the following would cause a false-negative result in DAT?
Correct Answer
B. Not washing red cells thoroughly.
Explanation
Not washing red cells thoroughly would cause a false-negative result in DAT because the test relies on the detection of antibodies or complement proteins attached to the surface of red blood cells. If the red cells are not properly washed, any antibodies or complement proteins present may not be adequately removed, leading to a false-negative result where the presence of these substances is not detected.
35.
Which of the following intradermal neutralization tests is used to diagnose diphtheria?
Correct Answer
D. Schick's test
Explanation
The Schick's test is used to diagnose diphtheria. This test involves injecting a small amount of diphtheria toxin into the skin and observing for a local reaction. If there is no reaction, it indicates that the person is susceptible to diphtheria and may require vaccination.
36.
The end of cell mediated immunity is
Correct Answer
C. Antigen epitope presentation by HLA
Explanation
Antigen epitope presentation by HLA refers to the process where antigens are presented to T cells by the major histocompatibility complex (MHC) molecules. This is a crucial step in cell-mediated immunity as it allows T cells to recognize and respond to specific antigens. Once the T cells recognize the antigens, they can initiate an immune response to eliminate the pathogen or infected cells. Therefore, antigen epitope presentation by HLA marks the end of cell-mediated immunity as it is the final step in activating the immune response.
37.
Which of the following is true?
Correct Answer
B. The specimen for RID C3c assay is inactivated serum.
Explanation
RID assays are used to measure the levels of certain proteins in serum, such as complement components. For the C3c assay, serum is often treated to inactivate complement to prevent activation during the assay process.
38.
Which of the following is incorrect?
Correct Answer
C. CD4 receptors are responsible for the rosette formation of sheep erythrocytes.
Explanation
The formation of rosettes with sheep erythrocytes is typically associated with T cells with CD2 surface proteins, not CD4. CD4 receptors are present primarily on helper T cells and are not responsible for the binding of sheep erythrocytes.
39.
All of the following are true of IgE except that it
Correct Answer
B. Is heat stable
Explanation
IgE is an antibody primarily involved in responses to allergens and is known for its role in the immune system's allergic responses and in immunity against parasites. IgE binds to allergens and triggers histamine release from mast cells and basophils, thereby contributing to inflammation and other allergic symptoms. Key characteristics of IgE include its ability to attach to tissue mast cells and its presence in the serum of allergic individuals. It also fails to fix complement, which is a system used for enhancing the ability of antibodies and phagocytic cells to clear microbes and damaged cells. However, IgE is sensitive to heat and is not heat stable, which is the correct response to the question as it does not maintain its function when exposed to high temperatures.
40.
Which of the following are L chains of an antibody molecule?
Correct Answer
A. Kappa
Explanation
The L chains of an antibody molecule can be either kappa or lambda. In this case, the correct answer is kappa, which is one of the possible L chains of an antibody molecule.
41.
The structure formed by the fusion of engulfed materials and enzymatic granules within a phagocytic cell is called a
Correct Answer
D. pHagolysosome.
Explanation
A phagolysosome is the structure formed by the fusion of engulfed materials and enzymatic granules within a phagocytic cell. This structure combines the functions of a phagosome, which is responsible for engulfing and containing the materials, and a lysosome, which contains enzymes to break down the engulfed materials. Therefore, the correct answer is phagolysosome.
42.
What is the advantage of VDRL over RPR?
Correct Answer
B. CSF can be used as a specimen for VDRL.
Explanation
The advantage of VDRL over RPR is that CSF (Cerebrospinal Fluid) can be used as a specimen for VDRL. This means that VDRL can be used to diagnose syphilis in cases where CSF is the only available specimen, which is not possible with RPR.
43.
Which of the following can be attributed to antigen-stimulated T cells?
Correct Answer
C. Cytokines
Explanation
Antigen-stimulated T cells play a crucial role in the immune response by releasing cytokines. Cytokines are small proteins that act as chemical messengers, allowing T cells to communicate with other immune cells. They regulate various immune responses, including inflammation, cell proliferation, and differentiation. Therefore, the presence of cytokines can be attributed to antigen-stimulated T cells. The other options, such as humoral response, plasma cells, and antibodies, are more closely associated with B cells and the production of antibodies.
44.
Which represents the main function of IgD?
Correct Answer
C. Enhancing the proliferation of B cells
Explanation
IgD plays a role in enhancing the proliferation of B cells. It is a type of antibody that is found on the surface of B cells and helps to activate and stimulate the growth of B cells. This is important for the immune response, as B cells are responsible for producing antibodies to fight off infections. Therefore, the main function of IgD is to support the proliferation and activation of B cells.
45.
All of the following are true of the recognition unit except that
Correct Answer
C. It is a part of the Properdin Pathway.
Explanation
The recognition unit consists of C1q, C1r, and C1s, and the subunits require calcium for binding together. C1q activates C4. However, it is not a part of the Properdin Pathway.
46.
Which of the following is the most commonly used method to detect antibodies in a patient's serum?
Correct Answer
B. Enzyme-Linked Immunosorbent Assay (ELISA)
Explanation
ELISA is the most commonly used method to detect antibodies in a patient’s serum. It involves the binding of antibodies to specific antigens and uses enzyme-labeled detection systems to produce a measurable signal. ELISA is widely used for its sensitivity, specificity, and ability to test multiple samples quickly. While PCR and Western Blot are useful in molecular and protein detection, ELISA remains the primary tool for antibody testing.
47.
Flagellar antigens are designated
Correct Answer
C. "H" antigens
Explanation
The "H" antigens are a crucial component in the classification and identification of certain bacteria, particularly in the genus Salmonella. These antigens are protein structures that constitute the flagella, which are whip-like appendages protruding from the cell body of bacteria. The flagella play a pivotal role in bacterial motility, allowing the bacteria to navigate through their environment.
48.
In an Ouchterlony immunodiffusion reaction with antigens 1 and 2, if crossed lines result, what does this indicate?
Correct Answer
D. The two antigens are unrelated.
Explanation
In an Ouchterlony immunodiffusion reaction, crossed lines indicate that the two antigens are unrelated. This means that there is no reaction or interaction between the antigens, suggesting that they do not share any common epitopes or similarities. Therefore, the crossed lines indicate that there is no antigen-antibody binding occurring between antigens 1 and 2, indicating that they are unrelated.
49.
The most abundant circulating antibody in human plasma is
Correct Answer
A. IgG
Explanation
IgG is the most abundant circulating antibody in human plasma. It is the main antibody involved in secondary immune responses and provides long-term immunity against pathogens. IgG can cross the placenta, providing passive immunity to the fetus, and it also plays a role in opsonization, neutralization, and activation of complement. IgM is the first antibody produced during an initial immune response, but it is not as abundant as IgG in the circulation. IgD, IgE, and IgA have more specialized roles in the immune system and are not as abundant as IgG in the plasma.
50.
Who developed the Side Chain Theory of antibody formation?
Correct Answer
A. Ehrlich
Explanation
Ehrlich developed the Side Chain Theory of antibody formation.