front 1 Most bacteria grow best at pH | back 1 pH 7 |
front 2 A sample of well water is tested for its bacterial content in a plate count assay. A one-milliliter sample of the water is diluted in a 1:10 dilution series. One milliliter of the fourth dilution tube is plated in a pour plate. After incubation, the plate has 83 colonies, indicating that the original water sample contained | back 2 830,000 cells per milliliter. |
front 3 Which of the following is an advantage of the direct microscopic count? | back 3 requires no incubation time |
front 4 The ________ method is used to indirectly measure microbial growth of filamentous bacteria and molds. | back 4 dry weight |
front 5 Assume you inoculated 100 cells, with a generation time of 20 minutes, into 100 ml of nutrient broth. You then inoculated 100 cells of the same species into 200 ml of nutrient broth. After incubation for 3 hours, you can reasonably expect to have | back 5 the same number of cells in both. |
front 6 For the three types of media in Table 6.1, which medium (or media) is/are chemically defined? | back 6 A |
front 7 Which of the following is an advantage of the standard plate count? | back 7 determines the number of viable cells |
front 8 The source of nutrients in nutrient agar is | back 8 peptone and beef extract. |
front 9 Three cells with generation times of 60 minutes are inoculated into a culture medium. Assuming no lag phase takes place, how many cells are there after 5 hours? | back 9 96 |
front 10 Which of the following is an example of a metabolic activity that could be used to measure microbial growth? | back 10 glucose consumption |
front 11 When cultivating anaerobic organisms in the laboratory setting, a candle jar is sufficient for the vast majority of organisms. | back 11 False |
front 12 Figure 6.1, which line best depicts a facultative anaerobe in the absence of O2? | back 12 b |
front 13 Figure 6.2 shows a typical bacterial growth curve with the y-axis indicating the log of the number of bacteria and the x-axis indicating time in culture. In the figure, which section (or sections) shows a growth phase where the number of cells dying equals the number of cells dividing? | back 13 c |
front 14 Most fungi grow best at pH | back 14 5 |
front 15 Which enzyme catalyzes the reaction: O2- + O2- + 2H+ → H2O2 + O2? | back 15 superoxide dismutase |
front 16 The biosafety level (BSL) for a clinical microbiology laboratory working with potentially airborne pathogens, such as tuberculosis bacteria, is | back 16 BSL-3. |
front 17 Pure cultures can easily be obtained on streak plates, even if the desired bacteria are present in very low concentrations in the initial culture broth. | back 17 True |
front 18 In Figure 6.1, which line best illustrates the growth of a facultative anaerobe incubated aerobically? | back 18 a |
front 19 Which of the following is an organic growth factor? | back 19 vitamin B1 |
front 20 Thirty-six colonies grew in nutrient agar from 1.0 ml of undiluted sample in a standard plate count. How many viable and culturable cells were in the original sample? | back 20 36 per milliliter |
front 21 A sample of ocean water is tested for its bacterial content in a plate count assay. A one-milliliter sample of the water is diluted in a 1:10 dilution series. 0.1 milliliter of the second dilution tube is plated in a pour plate. After incubation, the plate has 191 colonies, indicating that the original water sample contained | back 21 191,000 cells per milliliter. |
front 22 In measuring turbidity of a culture in indirect measurement of bacterial growth, absorbance and transmittance are identical and interchangeable values. | back 22 false |
front 23 Which of the following elements is NOT correctly matched with its cellular function? | back 23 phosphorus – used for production of carbohydrates. |
front 24 In Figure 6.1, which line best depicts an obligate anaerobe in the presence of O2? | back 24 c |
front 25 A sample of milk is tested for its bacterial content in a plate count assay. A one-milliliter sample of the milk is diluted in a 1:10 dilution series. One milliliter of the third dilution tube is plated in a pour plate. After incubation, the plate has 54 colonies, indicating that the original milk sample contained | back 25 54,000 cells per milliliter. |
front 26 In Figure 6.3, which tube shows the expected growth pattern for a facultative anaerobe? | back 26 b |
front 27 Which of the following is NOT a direct method to measure microbial growth? | back 27 metabolic activity |
front 28 Patients with indwelling catheters (long-term tubes inserted into body orifices for drainage, such as through the urethra and into the urinary bladder) are susceptible to infections because | back 28 biofilms develop on catheters. |
front 29 Most pathogenic bacteria are thermophiles. | back 29 false |
front 30 Bacterial growth refers to an increase in the numbers of cells in a bacterial culture. | back 30 true |
front 31 In one hospital, Pseudomonas aeruginosa serotype 10 infected the biliary tract of 10 percent of 1300 patients who underwent gastrointestinal endoscopic procedures. After each use, endoscopes were washed with an automatic reprocessor that flushed detergent and glutaraldehyde through the endoscopes, followed by a tap water rinse. P. aeruginosa serotype 10 was not isolated from the detergent, glutaraldehyde, or tap water. What was the source of the infections? | back 31 a biofilm in the reprocessor |
front 32 If cells are grown in media containing amino acids labeled with radioactive nitrogen (15N), most of the radioactivity will be found in the cells' | back 32 DNA and proteins. |
front 33 The U.S. Food and Drug Administration convention when performing pour or spread plate counts is to count only plates with ________ colonies. | back 33 25 to 250 |
front 34 The term aerotolerant anaerobe refers to an organism that | back 34 does not use oxygen but tolerates it. |
front 35 Salts and sugars work to preserve foods by creating a | back 35 hypertonic environment. |
front 36 The addition of which of the following to a culture medium will neutralize acids? | back 36 buffers |
front 37 Which enzyme catalyzes the following reaction? 2H2O2 → 2H2O + O2 | back 37 catalase |
front 38 During which growth phase will gram-positive bacteria be most susceptible to penicillin? | back 38 log phase |