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

Viruses produce _________ but bacterias do not.

  1. interferons

  2. endotoxins

  3. exotoxins

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

Interferons are a family of host-coded proteins produced by cells on induction by viral inducer. Interferon does not act on virus, but it renders other host cells refractory to virus. Interferons (IFNs) are natural cell-signaling proteins produced by the cells of the immune system of most vertebrates in response to challenges, such as viruses, parasites and tumour cells.

Multiple choice

Which of the following is true regarding the normal microbial flora present on the skin and mucous membranes?

  1. It cannot be eradicated by antimicrobial agents.

  2. It is absent in the stomach due to the acidic pH.

  3. It establishes in the body only after the neonatal period.

  4. The flora in the small bronchi is similar to that of the trachea.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The resident normal microbial flora cannot be completely or permanently removed, while transient ones are temporary. The number of superficial microorganisms can be diminished completely eradicated.

Multiple choice

Which of the given antibiotics can inhibit the transpeptidation reaction of peptidoglycan synthesis? Transpeptidation is a reaction involving the transfer of one or more amino acids from one peptide chain to another.

  1. Sulfonamides

  2. Polymyxin B

  3. Penicillin

  4. Valinomycin

  5. Gramicidin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Some antibacterial drugs, such as penicillin interferes with the production of peptidoglycan by binding to bacterial enzymes known as penicillin binding proteins or transpeptidases. Penicillins inhibit the transpeptidation reaction and block cross-linking of the cell wall. This results in lysis of the cell wall due to high internal osmotic pressure.

Multiple choice

Which of these can contribute to this toxicity of the lipopolysaccharide?

Lipopolysaccharide can act as an endotoxin, and cause some of the symptoms that arise in gram negative bacterial infections.

  1. Core polysaccharide

  2. Braun's lipoprotein

  3. O antigen

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

It is a major constituent of the outer membrane and is often toxic. The outer leaflet of the membrane comprises of a complex lipopolysaccharide whose lipid portion acts as an endotoxin. If the endotoxin enters the circulatory system, it causes a toxic reaction resulting in high temperature, high respiration rate and low blood pressure. This may lead to endotoxic shock which may be fatal.

Multiple choice

Why are bacteria an ideal choice for host cells?

  1. Bacteria are small in size.

  2. Bacteria have a rigid cell wall.

  3. Bacteria multiply rapidly.

  4. Bacteria have a single circular chromosome.

  5. Bacteria produce antibiotics.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Bacteria multiply at astounding rates. E. coli forms visible colonies within 24 hours. Hence, it is quick and easy to deal with.

Multiple choice

Cephalosporins are typical bactericidal antibiotics that help to inhibit bacterial cell wall synthesis through competitive inhibition of transpeptidase. The first generation cephalosporin antibiotics are known to possess better activity against gram-positive bacteria. Which of the following antibiotics is an example of first generation cephalosporin antibiotics?

  1. Cefoxitin

  2. Cefuroxime

  3. Cephalexin

  4. Ceftriaxone

  5. Cefotaxime
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cephalexin is an example of first generation cephalosporins. The first generation cephalosporin antibiotics are known to possess better activity against gram-positive bacteria.

Multiple choice

Aminoglycoside antibiotics are typical bactericidal that act as protein synthesis inhibitor, inhibiting 30S subunit of ribosome. Which of the following antibiotics does not belong to the group of aminoglycosides?

  1. Gentamicin

  2. Neomycin

  3. Tobramycin

  4. Streptomycin

  5. Tetracycline
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Tetracycline acts as bacteriostatic antibiotic that acts as protein synthesis inhibitor, blocking tRNA. It does not belong to the group of aminoglycosides.

Multiple choice

Various inhibitors are used in the study of the electron transport system at various levels of electron carriers. Which of the following antibiotics act as an inhibitor of the electron transport system between NADH dehydrogenase and cytochrome b?

  1. Atractyloside

  2. Antimycin A

  3. Bottromycin

  4. Bactoprenol

  5. Piericidin A
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Piericidin A is an antibiotic, produced by Streptomyces mobaraensis, that resembles coenzyme Q in its structure and inhibits the electron transport system between NADH dehydrogenase and cytochrome b.

Multiple choice

Macrolide group of antibiotics refers to the bacteriostatic antibiotics that inhibit protein synthesis by binding to the 50S ribosomal subunit. Which of the following antibiotics suits best for erythromycin?

  1. Aminoglycosides

  2. Chloramphenicol

  3. Macrolides

  4. Tetracyclines

  5. Spectinomycin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Erythromycin belongs to macrolide group of antibiotics that are bacteriostatic and inhibit protein synthesis by binding to the 50S ribosomal subunit.