Question
Microbiology Study Guide
22. Which of the following scientist made the accidental discovery of penicillin? A. Louis Pasteur B. Carl Linnacus C. Antonie Leeuwenhoek D. Robert Koch E. Alexander Fleming 23. All of the following are true for antibiotics except A. They are chemicals secreted by organisms to act against other organisms B. The antibiotics currently available can be natural, synthetic or semi-synthetic. C. Smaller the differences between the pathogen and the host, more effective is the antibiotic. D. Antibiotics are used against bacteria but not viruses. E. Different types of bacteria and fungi have been used to isolate antibiotics. 24. Success of chemotherapy depends on the selective toxicity of the drug on the pathogen vs. its host. B. False 25. There are limited number of antiviral drugs that are effective against human infections because A. Viruses are made of cells similar to human cell structure. B. Viruses attack human cells very aggressively C. Viruses were very recently discovered. D. Viruses depend on and use host enzymes and organelles to metabolize and replicate. E. Viruses are very small as compared to human cells. 26. In order to treat bacterial diseases, which of the following action of antimicrobial agent is most effective for killing the bacteria but at the same time be least harmful to human cells? A. Inhibition of cell wall synthesis. B. Disruption of cytoplasmic membranes. C. Inhibition of protein synthesis. D. Inhibition of DNA and RNA synthesis. E. Inhibition of cell metabolism. 27. Beta-lactams such as penicillin are antibacterial. This antibiotic acts by A. Inhibiting the formation of phospholipids, thereby disrupting bacterial cell membranes. B. Inhibiting the enzymes that link nucleotides to form DNA and RNA. C. Inhibiting the enzyme that cross-links NAM subunits to prevent new D. Blocking chemicals from going in or coming out of the bacterial cell. E. Blocking cellular respiration and ATP production. peptidoglycan formation. 28. Beta-lactams such as penicillin are antibacterial. Why is penicillin not prescribed to treat viral diseases such as common cold or flu? A. Because viruses reproduce rapidly and penicillin cannot compete with the rate of multiplication. B. Because viruses are resistant to penicillin. C. Because viruses lack cellular structures and enzymes on which penicillin acts. D. Because viruses are extremely small and they cannot be detected by penicillin. E. Because viruses form endospores that can survive penicillin treatment.
Explanation / Answer
Ans 22:
(E) Penicillin was accidentally discovered by Alexander Fleming.
Ans23) c:
Smaller the difference between the host and pathogen more effective is treatment (wrong statement).
Ans24) true (success of chemotherapy is based on difference in todicito to host and pathogen cell).
Ans25) (D) viruses depend on and use host enzyme /metabolism ....and replicate.
Ans 26) A- inhibition of cell wall ( as human don't have cell walls).
Ans 27: (C) inhibit Enzyme that cross links and thus inhibit peptidoglycan.
Ans 28: (c) because viruses lack cell structure and enzymes on on which penicillin acts.