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INF 309 > Micro department mcqs > Flashcards

Micro department mcqs Flashcards

1
Q

1- Which of the following micro organisms has a nuclear membrane?

a- Viruses
b- Fungi
c- Prions
d- Bacteria
e- Viroids

A

b- Fungi

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2
Q

2- Viruses have all the following characteristics EXCEPT:

a- They are one of the smallest infectious agents.
b- They have no cell structure.
c- They are obligate intracellular parasites.
d- They require the host biological machinery for their replication,
e- They are prokaryotic.

A

e- They are prokaryotic.

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3
Q

3- Prions:

a- Are single stranded circular RNA
b- Are devoid of proteins
c- Are infectious proteins devoid of nucleic acids
d- Are prokaryotic cells
e- Cause diseases in plants

A

c- Are infectious proteins devoid of nucleic acids

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4
Q

The following are functions of the cytoplasmic membrane EXCEPT:

a- Respiration
b- Cell wall biosynthesis
c- Reproduction
d- Staining affinity
e- Selective transport

A

d- Staining affinity

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5
Q

Lipid A is a cell wall component of:

a- Gram positive bacteria
b- Gram negative bacteria
c- Fungi
d- Algae
e- Viruses

A

b- Gram negative bacteria

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6
Q

3- One of the following is a function of the cell wall:

a- Maintaining the characteristic shape of the bacterial cell
b- Selective transport
c- Respiration, since respiratory enzymes are located in it
d- Protein synthesis
e- Excretion of extracellular enzymes

A

a- Maintaining the characteristic shape of the bacterial cell

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7
Q

4- All the following are characters of L-forms of bacteria EXCEPT:

a- They are naturally occurring bacteria without cell wall.
b- They are resistant to antibiotics which inhibit cell wall synthesis.
c- They develop only in isotonic media.
d- They can produce relapses of overt infections.
e- They may resynthesize the cell wall.

A

a- They are naturally occurring bacteria without cell wall.

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8
Q

5- Bacteria are protected from phagocytosis by:

a- The capsule
b- Lipoprotein
c- The mesosome
d- The outer membrane
e- Peptidoglycan

A

a- The capsule

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9
Q

6- All of the following are true concerning pili EXCEPT:

a- They mediate bacterial adherence.
b- They may be involved in bacterial conjugation.
c- Their antigen is called H antigen.
d- They are important virulence factors.
e- They are protein in nature.

A

c- Their antigen is called H antigen.

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10
Q

7- The marked resistance of the spores can be attributed to all the following factors EXCEPT:

a- The impermeability of their cortex and outer coat
b- Their ability to resist phagocytosis
c- Their low content of water
d- Their very low metabolic and enzymatic activity
e- Their high content of Ca and dipicolinic acid

A

b- Their ability to resist phagocytosis

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11
Q

1- What types of bacteria synthesize organic compounds from Inorganic compounds?

a- Heterotrophs
b- Obligate anaerobes
c- Aerobes
d- Facultative anaerobes
e- Autotrophs

A

e- Autotrophs

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12
Q

2- Which of the following terms best describes bacteria that lack catalase but not superoxide dismutase?

a- Obligate aerobe
b- Obligate anaerobe
c- Facultative anaerobe
d- Aerotolerant anaerobe
e- Microaerophilic

A

d- Aerotolerant anaerobe

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13
Q

3- Capnophillc bacteria require:

a- Low concentration of O2
b- High concentration of O2
c- High concentration of CO2
d- Alkaline pH
e- High temperature

A

c- High concentration of CO2

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14
Q

4- What type of bacterium is most likely to cause spoilage of refrigerated foods?

a- Mesophilic
b- Thermopjillc
c- Psychrophilic
d- Capnophillc
e- Microaerophilic

A

c- Psychrophilic

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15
Q

1- In lytic cycle of bacteriophages all the following occur EXCEPT:

a- Lysis of the bacterial host cell & release of newly formed phages,
b- The tail sheath contracts & nucleic acid is injected into the cell.
c- The phage attaches by its tail to a specific receptor.
d- The prophage is carried inside the bacterial cell indefinitely passing to daughter cells.
e- The phage components aggregate to form complete phage particles.

A

d- The prophage is carried inside the bacterial cell indefinitely passing to daughter cells.

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16
Q

2- The lysogenic bacterial cell Is the cell containing:

a- Lysosomes
b- Lysozymes
c- Bacteriocins
d- Prophage
e- Endospores

A

d- Prophage

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17
Q

1- Bacterial genetic information is carried on the following EXCEPT:

a- Ribosomes
b- Chromosome
c- Transposons
d- Plasmids
e- Bacteriophage

A

a- Ribosomes

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18
Q

2- Plasmids:

a- Are single-stranded DNA molecules
b- Carry optional genes (are dispensable)
c- Carry genes essential for growth
d- Are always found in linear form
e- Are always present as one copy/cell

A

b- Carry optional genes (are dispensable)

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19
Q

3- Plasmids differ from transposable genetic elements, as plasmids:

a- Become inserted into chromosomes
b- Are self-replicating outside the chromosome
c- Move from chromosome to chromosome
d- Carry genes for virulence (e.g. exotoxin production)
e- Carry genes for antibiotic resistance

A

b- Are self-replicating outside the chromosome

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20
Q

4- Plasmids may code for any of the following EXCEPT:

a- Sex pilus formation
b- Bacteriocin production
c- Growth
d- Antibiotic resistance
e- Virulence

A

c- Growth

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21
Q

5- Conjugative plasmids:

a- Are usually small in size
b- Carry fertility (F) factor
c- Are relaxed plasmids
d- Have a large copy number
e- Are common in Gram positive cocci

A

b- Carry fertility (F) factor

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22
Q

1- Transformation in bacteria depends on:

a- F factors
b- R factors
c- Bacteriophages
d- Cosmids
e- Competence of bacteria

A

e- Competence of bacteria

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23
Q

2- One of the following requires cell to cell contact.

a- Transformation
b- Conjugation
c- Transduction
d- Transcription
e- Transposition

A

b- Conjugation

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24
Q

3- Which of the following is mediated by a bacteriophage that carries host cell DNA:

a- Transformation
b- Conjugation
c- Transduction
d- Translation
e- Transcription

A

c- Transduction

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25
Q

4- Regarding generalized transduction:

a- It occurs during lytic cycle of bacteriophage.
b- It occurs during lysogenic cycle of prophage.
c- A specific piece of bacterial DNA is transferred from one cell to another.
d- Sex pilus is necessary.
e- It results in phenotypic variation of bacterial character.

A

a- It occurs during lytic cycle of bacteriophage.

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26
Q

1- Selective toxicity of an antibiotic:

a- Depends on presence of a receptor for the drug in hosts not in organisms
b- Is the ability of the drug to inhibit growth of a wide range of bacteria
c- Depends on inhibition of a biochemical event essential for the host
d- Is the ability of the drug to harm the organism without harming the host
e- Is one of the complications of antibiotic therapy

A

d- Is the ability of the drug to harm the organism without harming the host

27
Q

2- Which of the following antimicrobial agents is most toxic to humans?

a- Bacitracin
b- Cephalosporin
c- Amphotericin B
d- Penicillin
e- Vancomycin

A

c- Amphotericin B

28
Q

3- One of the following antimicrobial drugs is not among the group acting through inhibition of the bacterial cell wall:

a- Penicillin
b- Vancomycin
c- Cephalosporins
d- Bacitracin
e- Novobiocin

A

e- Novobiocin

29
Q

4- Which of the following antibiotics inhibits bacterial protein synthesis by acting on the 30S ribosomal subunit?

a- Vancomycin
b- Macrolides
c- Polymyxin
d- Aminoglycosides
e- Chloramphenicol

A

d- Aminoglycosides

30
Q

5- The following are mechanisms of acquired resistance to antimicrobial
agents EXCEPT:

a- Decreasing the influx of the antibiotic
b- Modification of the receptor (target) site
c- Target elimination by developing new metabolic pathways
d- Target overproduction
e- Absence of cell wall

A

e- Absence of cell wall

31
Q

6- The MIC is the:

a- Highest concentration of a drug required to inhibit bacterial growth
b- Standard dose of a drug required to inhibit bacterial growth
c- Lowest concentration of a drug required to inhibit bacterial growth
d- Lowest dilution of the a drug required to inhibit bacterial growth
e- Maximum dose of a drug required to inhibit bacterial growth

A

c- Lowest concentration of a drug required to inhibit bacterial growth

32
Q

7- Combined antibiotic therapy is indicated in the following conditions EXCEPT:

a- Mixed infections
b- T.B.
c- Viral meningitis
d- Endocarditis
e- Febrile neutropenia

A

c- Viral meningitis

33
Q

8- Regarding the effect of combined therapy with antimicrobial drugs, the expression, ”1 + 1 = >2” means:

a- Antagonistic effect
b- Synergistic effect
c- Indifference
d- Addition
e- Ineffectiveness

A

b- Synergistic effect

34
Q

1- One of the following statements is CORRECT:

a- Sterilization is complete removal or inactivation of all forms of microbial life,
b- Disinfection is elimination of all pathogenic organisms including spores,
c- Low level disinfection is effective against Mycobacterium tuberculosis.
d- Antiseptics are chemical disinfectants applied to surfaces and floors,
e- High level disinfection is enough for surgical instruments and needles.

A

a- Sterilization is complete removal or inactivation of all forms of microbial life,

35
Q

2- Pasteurization:

a- Is generally performed at 87°C for 30 minutes
b- Can destroy important pathogenic organisms
c- Is a method of sterilization
d- Is done by hot water at temperatures higher than 100°C
e- Cannot destroy Mycobacterium tuberculosis

A

b- Can destroy important pathogenic organisms

36
Q

3- Regarding hot air oven:

a- It is used to sterilize powders and petroleum products.
b- The sterilizing agent is moist heat.
c- It has a corroding effect.
d- It doesn’t necessitate prolonged exposure.
e- It is characterized by rapid and even penetration of heat into the materials to
be sterilized.

A

a- It is used to sterilize powders and petroleum products.

37
Q

4- Regarding biological indicators for monitoring autoclaves:

a- They are placed at the hottest part of the chamber.
b- They change their colour at 121°C
c- They are paper strips containing the spores of G. stearothermophilus.
d- Presence of bacterial growth indicates an efficient sterilization cycle,
e- They are checked for colour change at the end of each sterilization cycle.

A

c- They are paper strips containing the spores of G. stearothermophilus.

38
Q

1- Opportunistic pathogens:

a- Are never the cause of a clinical infection
b- Are usually highly pathogenic
c- Are rarely part of the normal flora
d- Cause disease mainly in immunocompromised individuals
e- Are resistant to killing by steam sterilization

A

d- Cause disease mainly in immunocompromised individuals

39
Q

2- Exotoxins have the following characters, EXCEPT:

a- They may be encoded by genes on the chromosome,
b- They can be converted to toxoids.
c- They have specific action.
d- They are polypeptides.
e- They are heat stable.

A

e- They are heat stable.

40
Q

3- Endotoxins:

a- Are secreted mainly by Gram-positive bacteria
b- Are highly antigenic
c- Are stable at temperatures above 60°C
d- Can be converted into toxoid
e- Have specific action

A

c- Are stable at temperatures above 60°C

41
Q

1- Viruses differ from bacteria in the following EXCEPT:,

a- They are very small in size.
b- They contain two types of nucleic acid.
c- They are obligatory intracellular parasites,
d- They need ultra-centrifugation for their sedimentation,
e- They can be seen only by the electron microscope

A

b- They contain two types of nucleic acid.

42
Q

2- All of the following is true concerning viral capsid EXCEPT:

a- It is formed of capsomers.
b- It is protein in nature.
c- It is responsible for viral symmetry.
d- It is the infectious part of the virus.
e- It protects the nucleic acid.

A

d- It is the infectious part of the virus.

43
Q

3- Local viral infections are characterized by:

a- Long incubation period
b- Short duration of immunity
c- Insignificant role of slgA
d- Important role of IgM and IgG
e- A stage of viraemia

A

b- Short duration of immunity

44
Q

1- Regarding innate immunity, all of the following is true EXCEPT:

a- It is present in all individuals since birth and at all times.
b- It is important at the beginning of infection.
c- It cannot tell the difference between pathogens.
d- It always eliminates infectious organisms successfully,
e- It involves mainly granulocytes.

A

d- It always eliminates infectious organisms successfully,

45
Q

5- Which statement about clonal selection theory is Correct:

a- Every naive lymphocyte has many types of receptors.
b- A clone of cells can recognize different antigens.
c- Only lymphocytes which meet antigens they recognize are activated,
d- The T cell receptor has 2 antigen recognition sites.
e- The B cell receptor cannot recognize an antigen directly.

A

c- Only lymphocytes which meet antigens they recognize are activated,

46
Q

Comparing BCR and TCR, which statement is TRUE?

a- The B and T cell receptors become released into the surroundings,
b- In contrast to BCR, TCR has 2 antigen binding sites,
c- Both are cell surface molecules.
d- Both molecules cooperate in innate immune mechanisms,
e- They bind to antigens non-specifically.

A

c- Both are cell surface molecules.

47
Q

1- All of the following is true regarding neutrophils EXCEPT:

a- They are phagocytic cells.
b- They constitute the majority of peripheral blood leucocytes,
c- They act mainly as part of the innate immune mechanism.
d- They are capable of killing abnormal cells by induction of apoptosis,
e- They are attracted to the site of infection by the action of chemotactic factors.

A

d- They are capable of killing abnormal cells by induction of apoptosis,

48
Q

3- Which statement is TRUE concerning acute phase proteins?

a. They disappear from the circulation after onset of infection.
b. Endotoxins may stimulate their production.
c. They deprive pathogens from their essential nutrients.
d. They are produced by the primary lymphoid organs.
e. Type IIFN is an example of acute phase proteins.

A

b. Endotoxins may stimulate their production.

49
Q

4- All the following statements regarding phagocytosis are true EXCEPT:

a- Bacteria are engulfed in phagosomes.
b- Natural killer cells are the most important phagocytic cells.
c- Respiratory burst is lethal to microorganisms.
d- Antibodies may aid in recognition.
e- Complement components (C3b) enhance phagocytosis.

A

b- Natural killer cells are the most important phagocytic cells.

50
Q

5- Enhanced phagocytosis is known as:

a- Agglutination
b- Opsonization
c- Neutralization
d- Antibody-dependent cellular cytotoxicity
e- Complement activation

A

b- Opsonization

51
Q

2- Antigenicity is increased by all of the following EXCEPT:

a- Chemical complexity of antigen
b- Foreignness
c- Being protein in nature
d- Very high dose of antigen
e- Large size of antigen

A

d- Very high dose of antigen

52
Q

1- One of the following is a co-stimulatory molecule:

a- CD40
b- CD40L
c- CD28
d- CD3
e- TCR

A

c- CD28

53
Q

3- Dendritic cells are involved in:

a- Transporting the epitope to the surface of a B cell
b- Suppressing the immune system
c- Destroying target cells
d- Presenting peptides to naive T cells
e- Producing antibody

A

d- Presenting peptides to naive T cells

54
Q

4- Extracellular bacteria are presented:

a- With MHC I to CD4 Th cells
b- With MHC I to CD8 Tc cells
c- With MHC II to B cells
d- With MHC II to CD4 Th cells
e- With MHC II to CD8 cells

A

d- With MHC II to CD4 Th cells

55
Q

5- The second signal needed for the activation of naive T cells is delivered
when:

a- CD40 ligand binds to CD40 molecule
b- CD4 binds to MHCII molecule
c- CD8 binds to MHCI molecule
d- CD3 binds to TCR
e- CD28 binds to B7 molecule

A

e- CD28 binds to B7 molecule

56
Q

6- Which statement about superantigens is INCORRECT?

a- They bind directly to MHC II molecule outside the peptide binding cleft,
b- They result in the release of huge amount of cytokines,
c- They result in stimulation of the normal acquired immune response,
d- They bind to the variable portion of the p chain of the TCR.
e- Unlike ordinary antigens, they are not processed in APCs.

A

c- They result in stimulation of the normal acquired immune response,

57
Q

7- Cytotoxic T cells exert their killing by:

a. Antibodies with specific recognition capabilities
b. Inserting the complement components into target cell membrane
c. T cell antigen receptors and MHC protein
d. Inserting a pore-forming protein called perforin into target cell membrane
e. Activation of macrophages

A

d. Inserting a pore-forming protein called perforin into target cell membrane

58
Q

1- Cytokines are characterized by all the following EXCEPT:

a- They may have a direct effect on the cells producing them,
b- They may have antagonistic effects.
c- Those affecting migration of lymphocytes are called chemokines.
d- Their action is antigen-specific.
e- They attach to specific cell surface receptors.

A

d- Their action is antigen-specific.

59
Q

2- One of the following is a pro-inflammatory cytokine:

a- IL-4
b- IL-5
c- TGF-p
d- IL-3
e- TNF-a

A

e- TNF-a

60
Q

3- Th1 cells are characterized by one of the following:

a- They produce IL-4.
b- They are activated by IL-4.
c- Their development is promoted by IL-4.
d- Their development is inhibited by IL-4.
e- Their functions are enhanced by IL-4.

A

d- Their development is inhibited by IL-4.

61
Q

4- All of the following statements about Th2 cells are true EXCEPT:

a. They produce IL-3, 4, 5 and 6.
b. Their development is inhibited by IFN-y.
c. They promote cell-mediated immunity.
d. Their development is promoted by IL-4.
e. They produce TGF-p

A

c. They promote cell-mediated immunity.

62
Q

5- IL-2 is produced by:

a- Activated macrophage
b- NK cells
c- Activated Th 1
d- Th2
e- B lymphocytes

A

c- Activated Th 1

63
Q

6- Interferon gamma:

a- Is considered the hallmark of Th2 cells
b- Promotes haematopoiesis
c- Is produced by activated macrophages
d- Is also called type I interferon
e- Increases expression of MHC molecules on different cells

A

e- Increases expression of MHC molecules on different cells

64
Q

7- One of the following cytokines promotes growth and differentiation of eosinophils:

a- IL-2
b- IL-10
c- TNF-a
d- IL-5
e- IL-1

A

d- IL-5

INF 309 (15 decks)

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