Microorganisms, living within biofilms typically use molecular signals to commun
ID: 83103 • Letter: M
Question
Microorganisms, living within biofilms typically use molecular signals to communicate with each to regulate density-dependent growth; this is commonly referred to as _____ a. horizontal gene transfer. b. quorum sensing. c. cytokine sensing. d. transduction gene transfer. Which of the following represents the best definition for microbial death? a. The organism no longer retains its original shape and structures. b. The organism will not grow on minimal medium. c. The organism will not grow on a medium that normally supports its growth. d. None of these adequately describe microbial death. The destruction or removal of all viable organisms is called _____ a. Sanitization b. antisepsis. c. disinfection. d. sterilization. The time required to kill 90% of the microorganisms or spores in a sample at a specified temperature is the _____ a. thermal death time (TDT) b. z value. c. decimal reduction time (D value). d. thermal death point (TDP). Moist heat sterilization at 100 degree C kills all the following EXCEPT a. viruses. b. bacterial endospores. c. fungal spores. d. Protists Who is usually credited with the discovery of penicillin? a. Fleming b. Duchesne c. Ehrlich d. Florey and Chain Which of the following does not inhibit protein synthesis? a. Erythromycin b. Streptomycin c. Penicillin d. Tetracycline e. All of the choices inhibit protein synthesis.Explanation / Answer
34. Microorganisms living in biofilm communicates with each through chemical molecular signals. Glue matrix in biofilm allow the concentration of cell produced chemical signal molecule to build up in sufficient quantity to cause changes the cellular behaviour.
Bacterial cells will activate a gene only when they are able to sense, via chemical signalling that their population is numerous enough to make it advantageous or safe to initiate genetic activity.
This system of population recognition is referred as quorum sensing.
So answer is option b.
35. When a organism is dead it will not grow in a medium in which it grows normally.
So answer is option c.
36. Destruction or removal of all viable oragnisms is called sterilisation . Answer is d.
37. Time required to kill 90 % of microorganisms or spores in a sample at specific temperature is called decimal reduction time or D value. Answer is option c.
38. Moist heat sterilisation at 100oC can't kill Bacterial endospores. Answer is b.
39.Sir Fleming was credited fir discovery of penicillin in 1928.
40. Penicillin
Itz mechanism of action us inhibition of celk wall synthesis, not inhibition of protein synthesis.