Why were the dilutions of 1:10,000 and 1:100,000 not

Given a shallow pan and a deep pot with the same volume, which would cool faster? Why?

Why is osmotic pressure an important factor in microbial growth?

Why is the prevention of biolms important in a health care environment?

What is the technical name for bacteria that require a higher-than-atmospheric-concentration of CO2 for growth?

In what way would an anaerobic chamber resemble the Space Laboratory orbiting in the vacuum of space?

If a technician were working with pathogenic prions, how would material leaving the lab be rendered noninfectious?

Of what value are hemolysins to pathogens?

Are bacteria capable of growing at a high osmotic pressure likely to be capable of growing in the mucus found in nostrils?

Is a colony formed as a result of streaking a plate always derived from a single bacterium? Why or why not?

In what way is budding dierent from binary ssion?

If a single bacterium reproduced every 30 minutes, how many would there be in 2 hours?

If the arithmetic numbers (solid line) were plotted for two more generations, would the line still be on the page?

Why were the dilutions of 1:10,000 and 1:100,000 not counted? Theoretically, how many colonies should appear on the 1:100 plate?

In what instances would the pour plate method be more appropriate than the spread plate method?

Could you make a pour plate in the usual Petri dish with a 10-ml inoculum? Why or why not?

Under what circumstances is the MPN method used to determine the number of bacteria in a sample?

This type of counting, despite its obvious disadvantages, is often used in estimating the bacterial population in dairy products. Why?

Why is turbidity more useful in measuring contamination of liquids by large numbers, rather than small numbers, of bacteria?

Assume you inoculated 100 facultatively anaerobic cells onto nutrient agar and incubated the plate aerobically. You then inoculated 100 cells of the same species onto nutrient agar and incubated the second plate anaerobically. Aer incubation for 24 hours, you should havea. more colonies on the aerobic plate.b. more colonies on the anaerobic plate.c. the same number of colonies on both plates

e term trace elements refers toa. the elements CHONPS.b. vitamins.c. nitrogen, phosphorus, and sulfur.d. small mineral requirements.e. toxic substances

Which one of the following temperatures would most likely kill a mesophile?a. 50Cb. 0Cc. 9Cd. 37Ce. 60C

Which of the following is not a characteristic of biolms?a. antibiotic resistanceb. hydrogelc. iron deciencyd. quorum sensing

Which of the following types of media would not be used to culture aerobes?a. selective mediab. reducing mediac. enrichment mediad. dierential mediae. complex media

An organism that has peroxidase and superoxide dismutase but lacks catalase is most likely ana. aerobe.b. aerotolerant anaerobe.c. obligate anaerobe.

Flask A contains yeast cells in glucoseminimal salts broth incubated at 30C with aeration. Flask B contains yeast cells in glucoseminimal salts broth incubated at 30C in an anaerobic jar. e yeasts are facultative anaerobes.a. Which culture produced more ATP?b. Which culture produced more alcohol?c. Which culture had the shorter generation time?d. Which culture had the greater cell mass?e. Which culture had the higher absorbance?

Assume that aer washing your hands, you leave ten bacterial cells on a new bar of soap. You then decide to do a plate count of the soap aer it was le in the soap dish for 24 hours. You dilute 1 g of the soap 1:106 and plate it on heterotrophic plate count agar. Aer 24 hours of incubation, there are 168 colonies. How many bacteria were on the soap? How did they get there?

Heat lamps are commonly used to maintain foods at about 50C for as long as 12 hours in cafeteria serving lines. Te following experiment was conducted to determine whether this practice poses a potential health hazard. Beef cubes were surface-inoculated with 500,000 bacterial cells and incubated at 4353C to establish temperature limits for bacterial growth. Te following results were obtained from heterotrophic plate counts performed on beef cubes at 6 and 12 hours afer inoculation Draw the growth curves for each organism. What holding temperature would you recommend? Assuming that cooking kills bacteria in foods, how could these bacteria contaminate the cooked foods? What disease does each organism cause? (Hint: See Chapter 25.)

Te number of bacteria in saliva samples was determined by collecting the saliva, making serial dilutions, and inoculating nutrient agar by the pour plate method. Te plates were incubated aerobically for 48 hours at 37C. What can you conclude from these data? Did all the bacteria present in each saliva sample grow?