Quiz Answers
- DNA vaccine contain………….. DNA that stimulates cells to make………….antigens.
- a. Human/ RNA
- b. Microbial/ Carbohydrate
- c. Human/Lipid
- d. Microbial/Protein ✅
- e. Human/ Protein
- Regarding the primary and secondary antibody responses, which one of the following statements is MOST accurate?
- a. The amount of IgG made in the secondary response is greater than the amount made in the primary response. ✅
- b. The lag phase is shorter in the primary response than in the secondary response.
- c. Antigen must be processed and presented in the primary response but not in the secondary response.
- d. In the primary response, memory B cells are produced, but memory T cells are not.
- e. The IgM made in the primary response is made primarily by memory B cells.
- “Isotype switching” of immunoglobulin classes by B cells involves:
- a. Simultaneous insertion of VH genes adjacent to each CH gene
- b. Activation of homologous genes on chromosome 6
- c. Successive insertion of a VH gene adjacent to different CH genes ✅
- d. Switching of light chain types (kappa and lambda)
- Of the following choices, the MOST important function of antibody in host defenses against bacteria is:
- a. Inhibition of bacterial protein synthesis
- b. Activation of lysozyme that degrades the cell wall
- c. Acceleration of proteolysis of exotoxins
- d. Facilitation of phagocytosis ✅
- In agglutination reactions, the antigen is a ……………… in precipitation reactions, the antigen is a ……………..
- a. Protein/ Carbohydrate
- b. Soluble molecule/ Whole cell
- c. Bacterium/ Virus
- d. Whole cell/ Soluble molecule ✅
- e. Protein/ Antibody
- Each of the following statements concerning haptens is correct EXCEPT:
- a. A hapten can combine with (bind to) an antibody.
- b. Haptens must be processed by CD8+ cells to become immunogenic. ✅
- c. A hapten cannot induce an antibody by itself; rather, it must be bound to a carrier protein to be able to induce antibody.
- d. In both penicillin-induced anaphylaxis and poison ivy, the allergens are haptens.
- An antibody directed against the idiotypic determinants of a human IgG antibody would react with:
- a. The Fc part of the IgG
- b. All human kappa chains
- c. All human gamma chains
- d. An IgM antibody produced by the same plasma cell that produced the IgG ✅
- An Rh-negative woman married to a heterozygous Rh-positive man has three children. The probability that all three of their children are Rh-positive is:
- a. 1:2
- b. 1:8 ✅
- c. 1:4
- d. Zero
- An immunoglobulin is a
- a. Glycoprotein ✅
- b. Fatty acid
- c. Protein
- d. Carbohydrate
- An antigen that overstimulates the immune system by binding nonspecifically to MHC on antigen-presenting cells is termed
- a. Non-specific antigen
- b. Toxic shock syndrome
- c. Super necrotic
- d. Super antigen ✅
- e. Epitope
- Individuals of blood group type AB:
- a. Are Rh(D)-negative
- b. Have circulating anti-A and anti-B antibodies
- c. Are “universal recipients” of transfusions ✅
- d. Have the same haplotype
- The membrane IgM and IgD on the surface of an individual B cell:
- a. Are identical except for their CH regions ✅
- b. Have identical heavy chains but different light chains
- c. Are identical except for their VH regions
- d. Have different VH and VL regions
- Which of the following antibodies would most likely be found in body secretions such as tears, milk, saliva, and mucus?
- a. IgG
- b. IgE
- c. IgM
- d. IgA ✅
- e. IgD
- Which one of the following is NOT true of the gene segments that combine to make up a heavy chain gene?
- a. A V segment and a J segment are preselected by an antigen to make up the variable-region portion of the gene. ✅
- b. Many V region segments are available.
- c. Several J segments and several D segments are available.
- d. V, D, and J segments combine to encode the antigen-binding site.
- Mitochondria are missing in
- a. Filamentous fungi
- b. Cestodes
- c. Protozoan parasites
- d. Yeasts
- e. Bacteria ✅
- Which one of the following statements is the MOST accurate comparison of human, bacterial, and fungal cells?
- a. Human and bacterial cells have plasmids, whereas fungal cells do not
- b. Human and fungal cells have a similar cell wall, in contrast to bacteria, whose cell wall contains peptidoglycan
- c. Human and fungal cells have similar ribosomes, whereas bacterial ribosomes are different ✅
- d. Human cells undergo mitosis, whereas neither bacteria nor fungi do
- Each of the following statements concerning bacterial spores is correct EXCEPT:
- a. They are formed by gram-positive rods
- b. They can be killed by being heated to 121°C for 15 minutes
- c. Their survival ability is based on their enhanced metabolic activity ✅
- d. They contain much less water than bacterial cells
- Which of the following BEST describes the mode of action of endotoxin?
- a. Degrades lecithin in cell membranes
- b. Blocks release of acetylcholine
- c. Causes the release of tumor necrosis factor ✅
- d. Inactivates elongation factor 2
- A cancer chemotherapy patient has to have her intravenous port revised after it becomes blocked and the catheter is found to contain bacterial contaminants. Which of the following attributes is most likely to be a factor in this pathogenesis?
- a. Possession of IgA protease
- b. Possession of pili
- c. Peptidoglycan layer
- d. Ergosterol-containing membrane
- e. Biofilm production ✅
- Each of the following statements concerning bacterial spores is correct EXCEPT:
- a. Spores are resistant to boiling
- b. Spores are formed primarily by organisms of the genus Neisseria ✅
- c. Spores are metabolically inactive and contain dipicolinic acid, a calcium chelator
- d. Spores are formed under adverse environmental conditions such as the absence of a carbon source
- Usually, bacteria form more endospores in response to:
- a. Nutrient surplus
- b. Adverse environmental stress ✅
- c. Colony formation
- d. Need for reproduction
- Each of the following statements concerning endotoxin is correct EXCEPT:
- a. They are part of the bacterial cell wall, whereas exotoxins are not
- b. They are less potent (i.e., less active on a weight basis) than exotoxins
- c. They are more stable on heating than exotoxins
- d. They bind to specific cell receptors whereas exotoxins do not ✅
- Each of the following statements regarding the selective action of antibiotics on bacteria is correct EXCEPT:
- a. Penicillins affect bacteria rather than human cells because bacteria have a cell wall, whereas human cells do not.
- b. Sulfonamides affect folic acid synthesis in bacteria, a pathway that does not occur in human cells. ✅
- c. Isoniazid affects the DNA polymerase of bacteria but not that of human cells.
- d. Chloramphenicol affects the large subunit of the bacterial ribosome, which is different from the large subunit of the human ribosome.
- A 12-year-old boy presents to his pediatrician with fever, malaise, and a sore throat. Physical examination reveals a fever of 103°F, cervical lymphadenopathy, and pharyngeal erythema. A swab is taken from some of the tonsillar exudate and cultured on blood agar. Culture reveals beta-hemolytic, gram-positive cocci, and a rapid antigen test is positive. What is the major component that protects the causal agent from osmotic damage?
- a. Lipopolysaccharide
- b. Polysaccharide
- c. Phospholipids
- d. Teichoic acid
- e. Peptidoglycan ✅
- The effect of endotoxin includes each of the following EXCEPT:
- a. Activation of the coagulation cascade
- b. Fever
- c. Hypotension
- d. Opsonization
- Bacterial surface structures that show antigenic diversity include each of the following EXCEPT:
- a. Peptidoglycan ✅
- b. Flagella
- c. Pili
- d. Capsules
- Which of the following microscopic techniques provide three-dimensional images of a bacterial cell?
- a. Transmission electron microscopy
- b. Scanning electron microscopy ✅
- c. Dark-field microscopy
- d. Fluorescent microscopy
- Each of the following statements concerning the surface structures of bacteria is correct EXCEPT:
- a. Pili mediate the interaction of bacteria with mucosal epithelium
- b. Polysaccharide capsules retard phagocytosis
- c. Both gram-negative rods and cocci have lipopolysaccharide “endotoxin” in their cell wall
- d. Bacterial flagella are nonantigenic in humans because they closely resemble human flagella in chemical composition ✅
- Each of the following statements concerning exotoxins are correct EXCEPT:
- a. When treated chemically, some exotoxins lose their toxicity and can be used as immunogens in vaccines
- b. Some exotoxins are capable of causing disease in purified form, free of any bacteria
- c. Some exotoxins act in the gastrointestinal tract to cause diarrhea
- d. Some exotoxins contain lipopolysaccharides as the toxic components ✅
- Each of the following statements concerning the structure and chemical composition of bacteria is correct EXCEPT:
- a. Some gram-positive cocci contain a layer of teichoic acid external to the peptidoglycan
- b. Some gram-negative rods contain lipid A in their cell wall
- c. Some mycoplasmas contain pentaglycine in their peptidoglycan ✅
- d. Some gram-positive rods contain dipicolinic acid in their spores
- The presence of a capsule around bacterial cells usually indicates their increased disease-causing potential and resistance to disinfection. Capsules are generally viewed by:
- a. Scanning electron microscopy
- b. Ziehl-Neelsen staining
- c. Gram staining
- d. Negative staining ✅
- What structure is most responsible for triggering Gram-negative shock?
- a. Capsule
- b. Periplasmic space
- c. Peptidoglycan-teichoic acid fragments
- d. Outer Membrane ✅
- e. Heat Shock Proteins
- What is an organism called that respires on the presence of oxygen and ferments in the absence of oxygen?
- a. Facultative anaerobe ✅
- b. Aerobe
- c. Anaerobe
- d. Facultative aerobe
- e. Microaerophile
- The MAIN host defense against bacterial exotoxins is
- a. Modulation of host cell receptors in response to the toxin
- b. IgG and IgM antibodies ✅
- c. Activated macrophages secreting proteases
- d. Helper T cells
- Identify correct statement regarding Robert Koch
- a. He is known as the father of bacteriology
- b. The causative organism of cholera, Vibrio cholera, was identified by him
- c. He discovered hypersensitivity phenomenon
- d. All the above ✅
- Father of antiseptic surgery is
- a. Louis Pasteur
- b. Robert Koch
- c. Antonie Van Leeuwenhoek
- d. Lister ✅
- Which among the following is a contribution by Louis Pasteur in the field of microbiology?
- a. Techniques of Pasteurization
- b. Process of Fermentation
- c. Rabies, cholera, and anthrax vaccine
- d. All the above ✅
- Mycobacterium leprae is also known as ……………
- a. Golden bacilli
- b. Koch’s bacillus
- c. Magical bacilli
- d. Hansen’s bacilli ✅
- Drug of choice to treat leprosy is ………
- a. Rifampicin
- b. Acyclovir
- c. Zidovudine
- d. Dapsone ✅
- Mycobacterium tuberculosis is also known as
- a. Golden bacilli
- b. Koch’s bacillus ✅
- c. Magical bacilli
- d. Hansen’s bacilli
- Correct statement regarding microscope is…….
- a. Electrons are used as a source of illumination in Electron microscope
- b. Antonie Van Leeuwenhoek developed the microscope first time
- c. Knoll & Ruska developed the electron microscope
- d. All the above ✅
- All of the following are acid-fast organisms EXCEPT
- a. Mycobacterium tuberculosis
- b. Nocardia
- c. Isospora belli
- d. Staphylococcus ✅
- Bacterial structure involved in respiration is
- a. Ribosome
- b. Pili
- c. Mesosome ✅
- d. Flagella
- Identify correct statement regarding bacteria
- a. Respiration, cell division, and sporulation are the functions of mesosome in bacteria
- b. Capsule in bacteria enables adherence to surface and protection against phagocytosis
- c. Heterotrophs are the bacteria that are unable to synthesize their own food materials
- d. All the above ✅
- Correct regarding cocci are ………….
- a. Cocci are spherical-shaped bacteria
- b. Cocci present in a chain is known as streptococci
- c. Cocci present in the shape of grapes is known as staphylococci
- d. All the above ✅
- Comma-shaped bacteria are known as
- a. Staphylococci
- b. Streptococci
- c. Vibrio ✅
- d. Bacillus
- Which of the following is most resistant to sterilization?
- a. Tubercle bacilli
- b. Viruses
- c. Spores
- d. Prions ✅
- Endoscope is sterilized by:
- a. Glutaraldehyde ✅
- b. Formaldehyde
- c. Autoclaving
- d. Hot air oven
- Recommended transport medium for stool specimen suspected to contain Vibrio cholerae is:
- a. Buffered glycerol saline medium ✅
- b. Venkatraman-Ramakrishanan medium
- c. Nutrient broth
- d. Blood agar
- Which is an enriched medium?
- a. Selenite F broth
- b. Peptone water ✅
- c. MacConkey agar
- d. Chocolate agar