This set of Microbiology Multiple Choice Questions & Answers (MCQs) focuses on “Major Groups of Antimicrobial Agents”.
1. How much percentage of aqueous solution of phenol rapidly kills the vegetative cells of microorganisms?
Explanation: Phenol is a very effective disinfectant.A 5% aqueous solution of phenol rapidly kills the vegetative cells of microorganisms; spores are much more resistant.
2. The antimicrobial activity of phenolics is not reduced at which of the following conditions?
a) acidic pH
b) alkaline pH
c) low temperatures
d) presence of soap
Explanation: The antimicrobial activity of phenolics is reduced at an alakaline pH and by organic material.Low temperaturs and the presence of soap also reduce antimicrobial activity.
3. Alcohol concentrations above 60% are effective against _________________
Explanation: Alcohol concentrations above 60% are effective against viruses; however the effectiveness is influenced considerably by the amount of extraneous proteinmaterial in the mixture.The extraneous protein reacts with the alcohol and thus protects the virus.
4. Polyvinylpyrrolidone (PVP) is a complex belonging to which group?
a) Phenolic compounds
Explanation: Polyvinylpyrrolidone (PVP) is a complex belonging to iodophors.Iodophors are mixtures of iodine with surface-active agents which act as carriers and solubilizers for the iodine.They possess the germicidal characteristics of iodine.
5. Which of the following agents irreversibly oxidize and inactivate proteins with sulphydral groups?
Explanation: Iodine is an oxidizing agent and oxidizing agents can irreversibly oxidize and thus inactivate essential metabolic compounds such as proteins with sulphydral groups.
6. Chlorinated lime is the alternative name for __________________
a) Calcium hypochlorite
b) Sodium hypochlorite
Explanation: Calcium hypochlorite, Ca(OCl)2 is also known as chlorinated lime and it acts as an effective disinfectant like free chlorine.
7. Chloramines are more stable than than hypochlorites.
Explanation: One of the advantage of chloramines is stability; they are more stable than the hypochlorites in terms of prolonged release of chlorine.
8. Solutions of sodium hypochlorite of a 1% concentration are used for ________
a) sanitizing dairy equipments
b) personal hygiene and a household disinfectant
c) household bleaches
d) disinfecting open wounds
Explanation:Solutions of sodium hypochlorite of a 1% concentration are used for personal hygiene and as a household disinfectant and higher concentrations of 5-12% are also employed as household bleaches.
9. Which among the following is an example of organic compound of mercury?
a) Mercuric chloride
b) Mercuric oxide
d) Ammoniated mercury
Example: Mercurochrome is an organic compound of mercury which are less irritating and less toxic than the inorganic mercury compounds.They are employed as antiseptics on cutaneous and mucosal surfaces.
10. Which of the following agents cause death to the cell by coagulation of cytoplasmic proteins?
d) Heavy metals
Explanation: High concentration of salts of heavy metals like mercury,silver, and copper coagulate cytoplasmic proteins resulting in damage or death to the cell.Salts of heavy metals are also precipitants and in high concentration they cause death of cell.
11. Gram-negative organisms are more susceptible to higher concentrations of triphenylmethane dyes.
Explanation: Gram-positive organisms are more susceptible to lower concentrations of triphenylmethane dyes than are Gram-negative ones.
12. Which of the following is an acridine dye?
a) crystal violet
b) malachite green
d) brilliant green
Explanation: Two examples of dyes derived from acridine are acriflavine and tryptoflavine.These compounds exhibit selective inhibition against bacteria,particularly staphylococci and gonococci.
13. Gonococci are inhibited by tryptoflavine in dilutions of ____________________
Explanation: Gonococci are inhibited by tryptoflavine in dilutions of 1:10,000,000 to 1:50,000,000.They possess little,if any, antifungal activity.
14. Ceepryn belongs to which of the following categories?
a) Anionic detergents
b) Cationic detergents
c) Nonionic detergents
d) Ammonium salts
Explanation: Those which ionize with the detergent property resident in the cation are referred as cationic detergents.An example of this is Ceepryn which is Cetylpyridinium chloride.
15. Which of the following agents are used as a preservative in ophthalmic solutions?
b) quaternary ammonium salts
Explanation: The combined properties of germicidal activity and low toxicity,high solubility in water, stability in solution, and non-corrosiveness have resulted in many applications of quaterneries as disinfectants and sanitizing agents.They are used as skin disinfectants, as a preservative of ophthalmic solutions etc.
Sanfoundry Global Education & Learning Series – Microbiology.
To practice all areas of Microbiology, here is complete set of 1000+ Multiple Choice Questions and Answers.