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1 Gas-liquid chromatography is normally used to identify a. cellular metabolites. b. fatty acids c. products of pyrolysis d. all of the above 2. The use of rRNA gene sequences to identify bacterial strains is referred to as _______. 3.The ________ hypothesis proposes that mitochondria and chloroplasts developed from free-living procaryotes that invaded a precursor to the eucaryotes and established a stable relationship 4The exponential growth rate of a bacterial culture is affected by all of the following except a. the genetic potential of the organism b. the composition of the growth medium c. the number of cells initially inoculated into the culture vessel d. the condition of incubation (Because that only affect the length of lag phase) 5. The total number of viable microorganisms remains constant in stationary phase because a. there is a balance between cell division and cell death b. there is a cessation of cell division even though the cells may remain metabolically active. c. either there is a balance between cell division and cell death or there is a cessation of cell division even though the cells remain metabolically active d. none of the above 6. Cells may enter stationary phase because of a. the depletion of an essential nutrient b. a lack of available oxygen c. the accumulation of toxic waste products d. all of the above 7. Which of these methods can be used to determine the number of viable microorganisms in a sample? a. light scattering in a spectrophotometer b. measuring total cell mass c. measuring colony forming units per ml d. counting a known volume of cells in a hemocytometer (only colony forming units can count only the living cells but not both living and dead) 8. A culture in a closed vessel to which no addition medium is added and form which no waste products are removed is called a _____ culture. a. continuous b. batch c. fed-batch d. semicontinuous 9. Microbial ____ is an increase in cell constituents that may or may not be accompanied by an increase in cell number ! (growth)

10. The _____ ______ is the length of time it takes for a population of microorganisms to double in number. ! (doubling time / generation time) 11. When a young, vigorously growing culture of bacteria is transferred to fresh medium of the same composition, the lag phase is usually short or absent. ! (True) 12. When a young, vigorously growing culture of bacteria is transferred to fresh medium of the different composition, the lag phase is usually short or absent. ! (False) 13. Microorganisms are most nearly uniform in terms of chemical and physiological properties during _____ phase. a. lag b. log c. stationary d. decline 14. Which of the following is a reason for the occurrence of a lag phase in a bacterial growth curve? a. The cells may be old and depleted of ATP, essential cofactor, and ribosomes that must be synthesized before growth can begin b. The medium may be different from the previous growth medium so that the cells must synthesize new enzymes to use different nutrients c. The organisms may have been injured and require time to recover d. All of these are potential reasons. 15. The rate growth of a given species of microorganism is dependent on the composition of the medium in which it is grown. ! (True) 16. The length of the lag phase of growth can vary depending on a. the condition of the microorganisms b. the nature of the growth medium c. the temperature d. all of the above 17. During the lag phase of microbial growth, the cells are metabolically inactive. ! (False, because the cells are making enzyme and having other internal activities)

1. A culture system with constant environmental conditions maintained through continual provision of the nutrient and removal of wastes is called ______ culture system. a. continuous b. batch c. fed-batch d. semicontinuous 2. An open system in which the growth rate is maintained by adding a nutrient (present in limiting quantities) at the same rate that medium containing microorganisms is removed is called a. manostat b. chemostat c. turbidostat d. culturostat (Chemostat contains limiting nutrient by definition) 3. An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a a. manostat b. chemostat c. turbidostat d. culturostat 4. In an open culture system, the rate at which media is added and removed is called the ______ rate. a. dilution b. chemostatic c. pass-through d. flow-through 5. Which of the following is considered a cardinal growth temperature? a. the minimum temperature b. the maximum temperature c. the optimum temperature d. All of these are considered cardinal growth temperatures 6. Organisms that grow well at 0℃ and have optimum growth temperatures of 15℃ or lower are called a. psychrotrophs b. psychrophiles c. frigiphiles d. mesophiles (Microorganisms that grow at low temperature) 7. Organisms that grow well at 0℃ and have optimum growth temperatures between 20℃ and 30℃ are called a. psychrotrophs b. psychrophiles c. frigiphiles d. mesophiles (Microorganisms usually grow at ordinary temperature but can grow at low as well)

8. Organisms that do not require oxygen for growth but grow better in its presence are called a. facultative anaerobes b. microaerophilies c. aerotolerant d. anoxygenic 9. Organisms that ignore oxygen and grow equally well in its presence or absence are called a. facultative anaerobes b. microaerophilies c. aerotolerant d. anoxygenic 10. Organisms that are damaged by the normal atmospheric level of oxygen (20%) but require oxygen at levels of 2-10% for growth are called a. facultative anaerobes b. microaerophilies c. aerotolerant d. anoxygenic 11. One of the major advantages of a continuous culture system is that the cells can be maintained in the exponential growth phase for extended periods of time. ! (True) 12. When a microorganism is placed in a(n) ______ solution, water will enter into the cell and cause it to burst unless something is done to prevent this. a. hypotonic b. isotonic c. hypertonic d. osmotonic 13. The membranes of psychrophilic bacteria have relatively high levels of ______ fatty acids, which allow them to remain semi-fluid at cold temperatures. a. saturated b. unsaturated c. sterol d. aromatic 14. Quorium sensing a. is a phenomenon in which bacteria monitor their own population density b. depends on the sensing of signal molecules called autoinducers c. plays an important role in formation of biofilms by Pseudomonas aeruginosa d. all of the above 15. The most common types of autoinducers in gram-negative bacteria are acyl homoserine lactones ! (True) 16. DNA of thermophiles is stabilized by binding of special histone proteins ! (True)

17. Membranes of some thermophilic bacteria are stabilized by ether linked phospholipids ! (True) 18. Membranes of thermophilic bacteria are stabilized by phospholipids with a. fatty acids that tend to be more saturated b. fatty acids that have lower molecular weights c. fatty acids that have more double bonds d. all of the above 19. Organisms that can use carbon dioxide as their sole or principal source of carbon are a. auxotrophs b. autotrophs c. prototrophs d. heterotrophs 20. Organisms that use reduced, performed organic molecules as carbon sources are a. auxotrophs b. autotrophs c. prototrophs d. heterotrophs


Microbiology Tutorial on 16/03/2010