MOCK MC EXAM BACTERIA & ANTIBIOTIC RESIST.

Question 1

Recite Koch’s 4 Postulates

Answer 1

1. Pathogen must be in all cases of disease and absent from healthy animals.
2. Suspected pathogen must grow in pure culture.
3. Cells from pure culture of suspected pathogen myst cause disease in healthy animal.
4. Suspected pathogen must be re-isolated and shown to be same as original.

Question 2

Which of the following mechanisms is NOT a common method by which bacteria develop resistance to antibiotics?

A) Horizontal gene transfer
B) Mutation in target genes
C) Antibiotic degradation
D) Increased antibiotic uptake

Answer 2

D) Increased antibiotic uptake

Question 3

Bacteria often employ efflux pumps to expel antibiotics from their cells, contributing to resistance. Which of the following is a primary role of efflux pumps in antibiotic resistance?

A) Facilitate antibiotic uptake
B) Increase antibiotic concentration in the cell
C) Pump antibiotics out of the cell
D) Modify the structure of antibiotics

Answer 3

C) Pump antibiotics out of the cell

Question 4

Cross-resistance occurs when resistance to one antibiotic results in reduced susceptibility to another. Which of the following is an example of cross-resistance?

A) Resistance to penicillin leading to increased susceptibility to tetracycline
B) Resistance to streptomycin leading to increased susceptibility to erythromycin
C) Resistance to ciprofloxacin leading to increased susceptibility to ampicillin
D) Resistance to vancomycin leading to increased susceptibility to gentamicin

Answer 4

B) Resistance to streptomycin leading to increased susceptibility to erythromycin

Question 5

Bacterial biofilms play a role in antibiotic resistance. What characteristic of biofilms contributes to their resistance to antibiotics?

A) Increased antibiotic penetration
B) Rapid bacterial growth
C) Presence of a protective extracellular matrix
D) Enhanced bacterial sensitivity

Answer 5

C) Presence of a protective extracellular matrix

Question 6

Why might combination therapy be used to combat bacterial resistance?

A) Increase the risk of side effects
B) Reduce the effectiveness of individual antibiotics
C) Target multiple pathways to decrease the likelihood of resistance
D) Simplify treatment regimens

Answer 6

C) Target multiple pathways to decrease the likelihood of resistance

Question 7

Which of the following antibiotics primarily targets bacterial cell wall synthesis?

A) Ciprofloxacin
B) Tetracycline
C) Penicillin
D) Erythromycin

Answer 7

C) Penicillin

Question 8

What is the primary role of plasmids in bacterial resistance?

A) Energy production
B) Protein synthesis
C) Storage of genetic information
D) Transfer of resistance genes

Answer 8

D) Transfer of resistance genes

Question 9

What does cross-resistance refer to in the context of bacterial resistance?

A) Resistance to multiple antibiotics within the same class
B) Resistance to antibiotics from different classes due to a common mechanism
C) Resistance to antibiotics in a specific bacterial species only
D) Resistance to antibiotics developed in cross-species experiments

Answer 9

B) Resistance to antibiotics from different classes due to a common mechanism

Question 10

Which of the following is an example of vertical gene transfer in the context of antibiotic resistance?

A) Transformation
B) Conjugation
C) Transduction
D) Mutation

Answer 10

A) Transformation

Question 11

The transfer of genetic material between bacteria through the uptake of naked DNA from the environment is known as:

a) Conjugation
b) Transformation
c) Transduction
d) Mutation

Answer 11

b) Transformation

Question 12

Which bacterial adaptation allows certain species to survive harsh environmental conditions by forming a thick-walled structure?

a) Endospore formation
b) Biofilm production
c) Capsule formation
d) Plasmid transfer

Answer 12

a) Endospore formation

Question 13

If a bacterial cell retains the crystal violet stain after the Gram staining process, what is its Gram classification?

a) Gram-positive
b) Gram-negative
c) Gram-variable
d) Gram-uncertain

Answer 13

a) Gram-positive

Question 14

Bacterial reproduction through binary fission results in:

a) Genetic recombination
b) Increased genetic diversity
c) Two identical daughter cells
d) Production of spores

Answer 14

c) Two identical daughter cells

Question 15

What is the primary mechanism of antibiotic resistance in bacteria that involves the transfer of genetic material through direct cell-to-cell contact?

a) Conjugation
b) Transformation
c) Transduction
d) Mutation

Answer 15

a) Conjugation

Question 16

Which of the following bacterial groups is characterized by a thick peptidoglycan layer in its cell wall?

a) Gram-positive bacteria
b) Gram-negative bacteria
c) Both Gram-positive and Gram-negative bacteria
d) Neither Gram-positive nor Gram-negative bacteria

Answer 16

a) Gram-positive bacteria

Question 17

Which of the following bacterial types is typically more resistant to antibiotics that target the cell wall?

a) Gram-positive bacteria
b) Gram-negative bacteria
c) Both Gram-positive and Gram-negative bacteria
d) Neither Gram-positive nor Gram-negative bacteria

Answer 17

b) Gram-negative bacteria

Question 18

Lipopolysaccharide (LPS) is a major component of the outer membrane in:

a) Gram-positive bacteria
b) Gram-negative bacteria
c) Both Gram-positive and Gram-negative bacteria
d) Neither Gram-positive nor Gram-negative bacteria

Answer 18

b) Gram-negative bacteria

Question 19

Which of the following bacterial groups is more susceptible to the effects of lysozyme?

a) Gram-positive bacteria
b) Gram-negative bacteria
c) Both Gram-positive and Gram-negative bacteria
d) Neither Gram-positive nor Gram-negative bacteria

Answer 19

a) Gram-positive bacteria

Question 20

The crystal violet-iodine complex is retained by which type of bacteria during the Gram staining process?

a) Gram-positive bacteria
b) Gram-negative bacteria
c) Both Gram-positive and Gram-negative bacteria
d) Neither Gram-positive nor Gram-negative bacteria

Answer 20

a) Gram-positive bacteria

Question 21

Which bacterial group is known for its high resistance to desiccation and harsh environmental conditions?

a) Gram-positive bacteria
b) Gram-negative bacteria
c) Both Gram-positive and Gram-negative bacteria
d) Neither Gram-positive nor Gram-negative bacteria

Answer 21

a) Gram-positive bacteria

Question 22

The presence of an outer membrane in the cell wall is a characteristic feature of:

a) Gram-positive bacteria
b) Gram-negative bacteria
c) Both Gram-positive and Gram-negative bacteria
d) Neither Gram-positive nor Gram-negative bacteria

Answer 22

b) Gram-negative bacteria

Question 23

How does Cholera toxin exert its effects on host cells?

a) Inhibiting protein synthesis
b) Increasing cAMP levels
c) Disrupting cell membranes
d) Inducing apoptosis

Answer 23

b) Increasing cAMP levels

Question 24

Which of the following bacterial structures is critical for Vibrio cholerae to colonize the small intestine?

a) Pili
b) Flagella
c) Capsule
d) Fimbriae

Answer 24

a) Pili