Q.1 Which of the following is an example of a β-lactam antibiotic?
Penicillin
Vancomycin
Erythromycin
Tetracycline
Explanation - Penicillins contain a β-lactam ring structure that interferes with bacterial cell wall synthesis.
Correct answer is: Penicillin
Q.2 What is the main target of aminoglycoside antibiotics?
Cell wall
DNA gyrase
30S ribosomal subunit
Folic acid synthesis
Explanation - Aminoglycosides bind to the 30S ribosomal subunit and cause misreading of mRNA.
Correct answer is: 30S ribosomal subunit
Q.3 Which antibiotic inhibits bacterial DNA gyrase?
Ciprofloxacin
Penicillin
Erythromycin
Vancomycin
Explanation - Fluoroquinolones like ciprofloxacin inhibit DNA gyrase, preventing DNA replication.
Correct answer is: Ciprofloxacin
Q.4 Sulfonamides act by inhibiting the synthesis of which bacterial compound?
Peptidoglycan
Folic acid
DNA
RNA
Explanation - Sulfonamides are competitive inhibitors of enzymes involved in folic acid synthesis.
Correct answer is: Folic acid
Q.5 Which antibiotic is used specifically against Mycobacterium tuberculosis?
Isoniazid
Ampicillin
Ciprofloxacin
Erythromycin
Explanation - Isoniazid inhibits synthesis of mycolic acids, a key component of mycobacterial cell walls.
Correct answer is: Isoniazid
Q.6 Vancomycin is primarily used to treat infections caused by:
Gram-negative bacteria
Gram-positive bacteria
Viruses
Fungi
Explanation - Vancomycin inhibits cell wall synthesis in Gram-positive organisms.
Correct answer is: Gram-positive bacteria
Q.7 Which of the following mechanisms is NOT a bacterial resistance mechanism?
Enzyme inactivation
Efflux pumps
Target modification
Increased human immunity
Explanation - Bacterial resistance is due to bacterial mechanisms, not host immune responses.
Correct answer is: Increased human immunity
Q.8 Which antibiotic binds to the 50S ribosomal subunit to inhibit protein synthesis?
Tetracycline
Streptomycin
Erythromycin
Gentamicin
Explanation - Erythromycin, a macrolide, binds to the 50S subunit and blocks protein elongation.
Correct answer is: Erythromycin
Q.9 Which resistance mechanism is associated with methicillin-resistant Staphylococcus aureus (MRSA)?
Altered penicillin-binding proteins
Efflux pumps
Enzyme degradation of DNA
Decreased immune response
Explanation - MRSA produces PBP2a, a modified penicillin-binding protein resistant to β-lactams.
Correct answer is: Altered penicillin-binding proteins
Q.10 The antibiotic tetracycline inhibits bacterial growth by:
Blocking cell wall synthesis
Inhibiting protein synthesis at 30S ribosome
Inhibiting DNA replication
Disrupting folate metabolism
Explanation - Tetracyclines bind to the 30S ribosome and prevent tRNA attachment.
Correct answer is: Inhibiting protein synthesis at 30S ribosome
Q.11 Which of the following antibiotics is considered bactericidal?
Penicillin
Tetracycline
Chloramphenicol
Sulfonamide
Explanation - Penicillin kills bacteria by disrupting cell wall synthesis, making it bactericidal.
Correct answer is: Penicillin
Q.12 Which antibiotic class includes drugs like gentamicin and streptomycin?
Aminoglycosides
Macrolides
Tetracyclines
Fluoroquinolones
Explanation - Gentamicin and streptomycin are aminoglycosides that bind the 30S ribosome.
Correct answer is: Aminoglycosides
Q.13 Which antibiotic disrupts bacterial cell membranes by binding to lipopolysaccharides?
Colistin
Ampicillin
Ceftriaxone
Erythromycin
Explanation - Colistin disrupts the outer membrane of Gram-negative bacteria by interacting with LPS.
Correct answer is: Colistin
Q.14 Which is the main mechanism of resistance to β-lactam antibiotics?
Mutation in ribosomes
Efflux pumps
Production of β-lactamases
Altered DNA gyrase
Explanation - Many bacteria produce β-lactamases, enzymes that degrade β-lactam antibiotics.
Correct answer is: Production of β-lactamases
Q.15 Chloramphenicol inhibits bacterial protein synthesis by binding to:
30S ribosomal subunit
50S ribosomal subunit
RNA polymerase
DNA gyrase
Explanation - Chloramphenicol binds to the 50S ribosome and prevents peptide bond formation.
Correct answer is: 50S ribosomal subunit
Q.16 Linezolid is classified as which type of antibiotic?
Macrolide
Oxazolidinone
Tetracycline
Glycopeptide
Explanation - Linezolid is an oxazolidinone antibiotic effective against resistant Gram-positive bacteria.
Correct answer is: Oxazolidinone
Q.17 Which of the following is an antifungal drug that targets ergosterol synthesis?
Amphotericin B
Fluconazole
Ciprofloxacin
Isoniazid
Explanation - Azoles like fluconazole inhibit ergosterol synthesis in fungal membranes.
Correct answer is: Fluconazole
Q.18 Which antibiotic inhibits RNA polymerase activity?
Rifampicin
Gentamicin
Erythromycin
Tetracycline
Explanation - Rifampicin binds to RNA polymerase and prevents transcription.
Correct answer is: Rifampicin
Q.19 Carbapenems belong to which antibiotic class?
β-lactams
Aminoglycosides
Tetracyclines
Macrolides
Explanation - Carbapenems are β-lactam antibiotics with a broad spectrum of activity.
Correct answer is: β-lactams
Q.20 Which mechanism allows bacteria to pump antibiotics out of the cell?
Enzymatic degradation
Efflux pumps
Altered target site
Biofilm formation
Explanation - Efflux pumps expel antibiotics, lowering intracellular concentration.
Correct answer is: Efflux pumps
Q.21 Which of the following is a glycopeptide antibiotic?
Vancomycin
Tetracycline
Ciprofloxacin
Amoxicillin
Explanation - Vancomycin is a glycopeptide that inhibits cell wall synthesis.
Correct answer is: Vancomycin
Q.22 Which is a major concern of antibiotic misuse?
Increased food production
Antibiotic resistance
Better immune system
Fewer bacterial infections
Explanation - Misuse of antibiotics leads to the emergence of resistant strains.
Correct answer is: Antibiotic resistance
Q.23 What is the mechanism of action of daptomycin?
Disrupts bacterial membrane potential
Blocks DNA replication
Inhibits RNA polymerase
Blocks folate synthesis
Explanation - Daptomycin binds to membranes and causes depolarization, leading to cell death.
Correct answer is: Disrupts bacterial membrane potential
Q.24 Which antibiotic is commonly used to treat urinary tract infections?
Nitrofurantoin
Vancomycin
Chloramphenicol
Amphotericin B
Explanation - Nitrofurantoin is effective against urinary pathogens and concentrated in urine.
Correct answer is: Nitrofurantoin
Q.25 What is the function of clavulanic acid in antibiotic therapy?
Directly kills bacteria
Inhibits β-lactamases
Disrupts ribosome
Blocks DNA synthesis
Explanation - Clavulanic acid protects β-lactam antibiotics by inhibiting β-lactamases.
Correct answer is: Inhibits β-lactamases