1. How may the following growth and culture conditions affect the length of the lag phase? EXPLAIN YOUR ANSWERS. a) inoculum is from an old culture b) shifting cells from rich culture medium to a poorer one c) exponentialy growing culture is transferred into the same medium under the same growth conditions

The average size of cells during the exponential phase of growth is... A) Less than the lag phase B) Same as delay phase C) Constant

1) The inactivation of Staphylococcus aureus was studied in pomegranate juice heated at 75°- 95°C. The slopes for the inactivation of this bacteria were calculated from the linear lines in semi-log graphical paper. The slope values were presented in Table 1. a) Determine the temperature change needed to inactivate this bacteria by 90%. b) Temperature change to inactivate Bacillus cereus in pomegranate juice by 90% at the same temperature range was 29°F. At 75°-95°C temperature range, which bacteria will be more affected by the temperature changes? Commend on your answer in one sentence Table 1- Slope values for the inactivation of Staphylococcus aureus in pomegranate juice heated at various temperature Temp. (°C) 75 80 85 95 -Slope x 10² (min-¹) 2.222 3.704 5.000 13.158

Which of the following is true regarding pathogenic strains of Staphylococcus and Streptococcus, respectively? A) O Staphylococcus aureus is a common cause of sore throats. B) O Alpha-hemolytic Streptococci turn blood agar green and include members that cause pneumonia and tooth decay, C) Gamma-hemolytic Streptococci completely lyse red blood cells on blood agar. D) O The beta-hemolytic group of Streptococci does not contain any pathogenic types.

The disc diffusion assay measuring a disinfectant's effectiveness against a microorganism is more standardized than measuring an antibiotic's effectiveness with the kirby-Bauer assay. a) True b) False

29) The doubling time in the bacterial growth cycle is measured during: a) Prodromal period b) Log phase c) Incubation period d) Convalescence period e) none of the above 34.Singlet oxygen that can kill bacteria is produced by: a) Catalase b) Superoxide Dismutase c) Sunlight radiation d) Gamma radiation e) c & d 35) Bacteria that can grow in your refrigerator but really loves your freezer is labelled as: a) Hypothermophile b) Psychrophile c) Psycrotroph d) Thermophobe e) Archaebacteria

What is the definition of the term Resistant?  How do you detect that your microorganism is resistant to a certain antibiotic?  What do you see on the Muller Hinton Agar plate?