Microbiology - General Microbiology (55 MCQ) Final Exam.

Microbiology - General Microbiology (55 MCQ) Final Exam. Question 1 : Which of the following is an important disinfectant on account of effectively destroying gram-positive and gram negative bacteria, viruses and even spores at low pH levels a) Phenol b) Alcohol c) Chlorine d) Hexachlorophene - CORRECT ANSWER c) Chlorine Question 2 : Conjugation does not involve a) Bacteriophages b) HFr c) Fr d) Plasmids - CORRECT ANSWER a) Bacteriophages Question 3 : All are sporonticidal except a) Lysol b) Glutaraldehyde c) Ethylene dioxide d) Formaldehyde - CORRECT ANSWER a) Lysol Question 4 : Phenol Co-efficient indicates a) Efficacy of a disifectant b) Dilution of a disinfectant c) Quantity of a disinfectant d) Purity of a disinfectant - CORRECT ANSWER a) Efficacy of a disifectant Question 5 : All are true regarding disinfectants except a) Glutaraldehyde is sporicidal b) Hypochlorites are virucidal c) Ethylene oxide is intermediate disinfectant d) Phenol usually requires organic matter to act - CORRECT ANSWER d) Phenol usually requires organic matter to act Two phenol derivatives commonly found as constituents of hospital disinfectants are ortho-phenylphenol and ortho-benzyl-para-chlorophenol. Residual disinfectant can irritate tissue Mode of Action: In high concentrations, phenol acts as a gross protoplasmic poison, penetrating and disrupting the cell wall and precipitating the cell proteins.