Question

11. Which of the following is most useful in representing population growth on a graph? a. logarithmic reproduction of the growth curve b. a semilogarithmic graph using a log scale on the y-axis c. an arithmetic graph of the lag phase followed by a logarithmic section for the log, stationary, and death phases d. none of the above would best represent a population growth curve 12. Which of the following methods is best for counting fecal bacteria from a stream to determine the safety of the water for drinking? a. dry weight c. viable plate counts b. turbidity d. membrane filtration 13. A Coulter counter is a a statistical estimation using 15 dilution tubes and a table of numbers to estimate the number of bacteria per milliliter b. an indirect method of counting microorganisms c. a device that directly counts microbes as they pass through a tube in front of an electronic detector d. a device that directly counts microbes that are differentially stained with fluorescent dyes 14. Lyophilization can be described as a freeze drying b. deep freezing c. refrigeration d. pickling 15. Quorum sensing is a, the ability to respond to changes in population density b, a characteristic of most bacteria c. dependent on direct contact among cells d. associated with colonies on an agar plate

Answer 1

11) c an arithmic graph of the lag phase followed by logarithmic section for the log phase , stationary and death phase .( cells population growth curve is the best example for this ).

12) c viable plate count ( best method to count colonies per ml of the solution ).

13) c device that directly counts microbes as they pass through a tube in front of the electronic detector.

14) a freeze drying ( cell water is removed to inactivate the cellular activity and add cryoprotectant to avoid ice crystal formation .)

15) a ability to respond to changes in population density ( bacteria can control their population due to increase production of autoinducer).