Biology

Antibiotics and Immunity

974 Questions

Prepare for your science sections with these questions on antibiotics and immunity. The hub covers various classes of antibiotics, their sources, and mechanisms of microbial resistance. It also addresses the human antiviral response.

Antibiotic classes and sourcesMicrobial resistance mechanismsAntiviral proteinsDisease treatments

Antibiotics and Immunity Questions

Multiple choice

Chloromycetin is

  1. antibacterial

  2. antidepressant

  3. an antiseptic

  4. analgesic
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Chloromycetin eye drops (Redidrops) and Chloromycetin eye ointment both contain the active ingredient chloramphenicol, which is a type of medicine called an antibiotic. Antibiotics are used to treat infections caused by bacteria.

Multiple choice

Which of the following bacteria are examples of Gram-positive bacilli?

P. Escherichia coli Q. Corynebacterium diphtheriae R. Neisseria gonorrhoeae S. Listeria monocytogenes

Select the correct answer using the codes given below:

  1. P and Q

  2. P and S

  3. Q and R

  4. Q and S

  5. R and S
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Corynebacterium diphtheriae is a Gram-positive, aerobic, non-motile, toxin-producing, rod-shaped (bacillus) bacteria belonging to the order Actinomycetales. Listeria monocytogenes is a Gram-positive rod-shaped (baccillus) bacterium that causes the infection listeriosis.

Multiple choice

Match compounds in Group I with inhibitory activities in Group II.

Group – I
Group – II
A. Chloramphenicol 1. Protein synthesis
B. Rifampin 2. RNA synthesis
C. Sulfadiazine 3. Folate synthesis
D. Vancomycin 4. Cell wall synthesis

  1. A - 1, B - 2, C - 3, D - 4

  2. A - 1, B - 3, C - 2, D - 4

  3. A - 2, B - 1, C - 4, D - 3

  4. A - 2, B - 3, C - 4, D - 1

  5. A - 3, B - 4, C - 2, D - 1
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Chloramphenicol is lipid-soluble and can easily diffuse through the bacterial cell membrane. It then reversibly binds to the L16 protein of the 50S subunit of bacterial ribosomes and prevents the transfer of amino acids to growing peptide chains. Thus, inhibits peptide bond formation and subsequent protein synthesis. Rifampin acts via the inhibition of DNA-dependent RNA polymerase, leading to a suppression of RNA synthesis and cell death. Sulfadiazine acts by Folate synthesis inhibition. It is a competitive inhibitor of the bacterial enzyme dihydropteroate synthetase needed for the proper processing of para-aminobenzoic acid (PABA) which is essential for folic acid synthesis. The inhibited reaction is necessary in these organisms for the synthesis of folic acid. Vancomycin acts by inhibiting proper cell wall synthesis in Gram-positive bacteria.

Multiple choice

Which of these statements about infection by bacteria in the gastrointestinal tract is FALSE?

  1. The acid in the stomach is sufficient to kill most gut pathogens.

  2. Helicobacter pylori is a commensal bacterium.

  3. Ammonia is produced by helicobacter. It helps this acid-sensitive bug to overcome the acid in the stomach. This ammonia provides protection against inflammation.

  4. Helicobacter is a rare infection.

  5. The bullous skin condition, dermatitis herpetiformis is linked to ulcerative colitis.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

On the contrary, ammonia is toxic to the mucosa.

Multiple choice

Which of the following is a semisynthetic antibiotic?

  1. Cloxacillin

  2. Dicloxacillin

  3. Flucloxacillin

  4. Nafcillin sodium
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cloxacillin is a semisynthetic antibiotic in the same class as penicillin. It is used against staphylococci that produce beta-lactamase, due to its large R chain, which does not allow the beta-lactamases to bind.

Multiple choice

Which of the following classes of antibiotics eventually leaves a bacterium unable to synthesise proteins that are vital to its growth by binding to 30S ribosomal unit?

  1. Macrolides

  2. Rifampicins

  3. Aminoglycosides

  4. Lincosamides
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Aminoglycosides bind to bacterial 30S ribosomal unit inhibiting the translocation of the peptidyl-tRNA from the A-site to the P-site and also causing misreading of mRNA, leaving the bacterium unable to synthesise proteins vital to its growth.

Multiple choice

Consider the following statements:

A: Cefuroxime is active against Haemophilus influenzae, N. gonorrhoeae and Lyme disease. B: It is less susceptible to beta lactamases.

  1. A is correct but B is incorrect

  2. A is incorrect but B is correct.

  3. Both A and B are correct but B is not the correct explanation of A

  4. Both A and B are correct and B is the correct explanation of A
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Both A and B are correct and B is the proper explanation of A. Cefuroxime is active against Haemophilus influenzae, N. gonorrhoeae and Lyme disease because it is less susceptible to beta lactamases that are produced by these bacteria.