prelim

Question 1

What are the three domains of life in bacterial classification?

Answer 1

Bacteria, Archaea, Eukarya

Question 2

What is the function of the bacterial cell wall?

Answer 2

Provides shape, structural support, and protection from osmotic pressure changes.

Question 3

What is the composition of the Gram-positive cell wall?

Answer 3

Thick peptidoglycan layer with teichoic and lipoteichoic acids.

Question 4

What is the composition of the Gram-negative cell wall?

Answer 4

Thin peptidoglycan layer, outer membrane with lipopolysaccharide (LPS), and periplasmic space.

Question 5

What is the function of porins in the bacterial outer membrane?

Answer 5

Regulate the passage of molecules, including antibiotics.

Question 6

What is the significance of Lipid A in Gram-negative bacteria?

Answer 6

It acts as an endotoxin causing fever and shock.

Question 7

Which genera of bacteria lack a cell wall?

Answer 7

Mycoplasma and Ureaplasma.

Question 8

What are fimbriae and their function?

Answer 8

Hair-like appendages that help bacteria adhere to surfaces.

Question 9

What are pili and their function?

Answer 9

Hollow protein tubes used for DNA exchange (conjugation).

Question 10

What is the function of bacterial flagella?

Answer 10

Provide motility and enable chemotaxis.

Question 11

What is the difference between monotrichous and peritrichous flagella?

Answer 11

Monotrichous has a single flagellum, peritrichous has flagella covering the entire surface.

Question 12

What are the four phases of bacterial growth?

Answer 12

Lag, Log (Exponential), Stationary, Death.

Question 13

What is the function of bacterial endospores?

Answer 13

Survive harsh conditions by entering a dormant state.

Question 14

Which genera are known for endospore formation?

Answer 14

Bacillus and Clostridium.

Question 15

What are the major types of bacterial metabolism?

Answer 15

Fermentation, respiration, and photosynthesis.

Question 16

What are the two main types of bacterial respiration?

Answer 16

Aerobic and anaerobic respiration.

Question 17

What is the role of bacterial plasmids?

Answer 17

Carry extra genes, often for antibiotic resistance or virulence.

Question 18

What are transposons?

Answer 18

Jumping genes that can move between plasmids and chromosomes.

Question 19

What are the three methods of horizontal gene transfer in bacteria?

Answer 19

Transformation, transduction, and conjugation.

Question 20

What is transformation in bacteria?

Answer 20

Uptake of naked DNA from the environment.

Question 21

What is transduction in bacteria?

Answer 21

Gene transfer mediated by bacteriophages (viruses).

Question 22

What is conjugation in bacteria?

Answer 22

Transfer of genetic material via direct cell-to-cell contact using a pilus.

Question 23

What is the function of the M protein in Streptococcus pyogenes?

Answer 23

Resists phagocytosis and helps adhesion to host cells.

Question 24

Which virulence factor allows Staphylococcus aureus to evade phagocytosis?

Answer 24

Protein A.

Question 25

What enzyme allows Staphylococcus aureus to clot plasma?

Answer 25

Coagulase.

Question 26

What is the significance of the catalase test in bacterial identification?

Answer 26

Differentiates Staphylococci (catalase-positive) from Streptococci (catalase-negative).

Question 27

What is the role of hyaluronidase in bacterial infection?

Answer 27

Breaks down connective tissue, aiding bacterial spread.

Question 28

What is the function of hemolysins in bacterial pathogenesis?

Answer 28

Lyse red blood cells to release nutrients for bacterial growth.

Question 29

What is the function of leukocidins in bacterial infections?

Answer 29

Destroy white blood cells, weakening the immune response.

Question 30

Which bacterial toxin is responsible for toxic shock syndrome?

Answer 30

Toxic shock syndrome toxin-1 (TSST-1).

Question 31

What type of bacteria are coagulase-negative Staphylococci (CoNS)?

Answer 31

Staphylococci that do not produce coagulase, e.g., S. epidermidis.

Question 32

Which species of Staphylococcus is associated with urinary tract infections in young women?

Answer 32

Staphylococcus saprophyticus.

Question 33

Which antibiotic is the treatment of choice for MRSA?

Answer 33

Vancomycin.

Question 34

What are the common virulence factors of Staphylococcus aureus?

Answer 34

Coagulase, hemolysins, Protein A, enterotoxins, TSST-1.

Question 35

Which enzyme enables Staphylococcus aureus to resist penicillin?

Answer 35

Penicillinase (β-lactamase).

Question 36

What are the Lancefield groups based on?

Answer 36

Carbohydrate composition of bacterial cell walls.

Question 37

Which test is used to differentiate Streptococcus pyogenes from other beta-hemolytic streptococci?

Answer 37

Bacitracin sensitivity test (Group A is sensitive).

Question 38

What is the CAMP test used for?

Answer 38

Identifies Group B Streptococcus (S. agalactiae) by its enhanced hemolysis pattern.

Question 39

What disease is associated with Streptococcus agalactiae in neonates?

Answer 39

Neonatal meningitis and sepsis.

Question 40

What is the causative agent of pneumonia that appears as lancet-shaped Gram-positive diplococci?

Answer 40

Streptococcus pneumoniae.

Question 41

What is the Quellung reaction used for?

Answer 41

Capsular swelling test to identify Streptococcus pneumoniae.

Question 42

Which bacteria are bile-esculin positive and grow in 6.5% NaCl?

Answer 42

Enterococcus species.

Question 43

What is the primary difference between Enterococcus and Streptococcus species?

Answer 43

Enterococcus can grow in high salt concentrations and is bile-esculin positive.

Question 44

What is the mode of transmission for zoonotic infections?

Answer 44

Direct contact, vector-borne transmission, or ingestion of contaminated food/water.

Question 45

What are exotoxins?

Answer 45

Toxins secreted by bacteria that target specific cells.

Question 46

What are endotoxins?

Answer 46

Toxins (Lipid A) released when Gram-negative bacteria die.

Question 47

What is the purpose of the optochin test?

Answer 47

Differentiates Streptococcus pneumoniae (sensitive) from other alpha-hemolytic streptococci (resistant).

Question 48

What are biofilms, and why are they important in infections?

Answer 48

Communities of bacteria enclosed in a self-produced matrix, making them highly resistant to antibiotics and immune responses.