STRAIGHTERLINE MICRO 250 PROCTORED
EXAM PREP LATEST 2026 WITH ACTUAL
QUESTIONS AND CORRECT VERIFIED DETAILED
ANSWERS ALREADY GRADED A
◉Streak plates are: Answer: Takes practice to master and requires skill
◉CFUs stand for what? Answer: Colony Forming Units
◉We will be using the spectrophotometer to measure what? Answer:
Turbidity
◉When counting colonies on a plate, you want to find a plate with how
many colonies: Answer: 30-300
◉The main idea for doing this lab is to: Answer: Make a standard curve
plot
◉In which of the following foods would you normally expect to find a
high number of bacteria? Answer: Yogurt
,◉Where would you expect to find members of the genus Pseudomonas?
Answer: In the soil
◉Where would you be most likely to find the fungus Penicillium?
Answer: In soils and waters
◉Where would you be most likely to find members of the genera
Escherichia? Answer: In the guts of mammals
◉How does bacterial enumeration help to determine if a food is safe for
consumption? Answer: This will give a general idea of the quality of the
food.
◉In which of the following food types would you expect to see high
numbers of microbes? Answer: Cheese
◉What does the presence of enteric organisms in milk indicate?
Answer: Fecal contamination of the milk occurred somewhere in the
production process.
◉Which of the following terms best describes the enumeration of
bacteria as described in your lab? Answer: A direct enumeration
, ◉You found 67 colonies on the ground beef plate with the 10^-2
dilution. What is the concentration of bacteria per milliliter of beef?
Answer: 6.7 × 10^3 CFU/ml
◉Which of the following is indicative of the presence of E. coli?
Answer: colonies on EMB agar with a metallic sheen
◉If you had fresh lettuce containing 9.3 × 10^3 organisms/ml, how
many colonies would you expect to see on a plate that represents a 10^-2
dilution? Answer: 93
◉Which of the following bacterial concentrations would produce a
TFTC plate at the 10^-4 dilution? Answer: 2 × 10^5 organisms/ml
◉Which of the following would produce a countable plate? Answer: A
solution containing 1.9 × 104 at a 10-2 dilution
◉After running this experiment, you find that the carrots you tested had
only 15 bacteria/ml. Your lab partner states that this number is so low
that the carrots do not need further treatment. Why should you disagree?
Answer: A low number of organisms does not indicate the absence of
pathogens.
EXAM PREP LATEST 2026 WITH ACTUAL
QUESTIONS AND CORRECT VERIFIED DETAILED
ANSWERS ALREADY GRADED A
◉Streak plates are: Answer: Takes practice to master and requires skill
◉CFUs stand for what? Answer: Colony Forming Units
◉We will be using the spectrophotometer to measure what? Answer:
Turbidity
◉When counting colonies on a plate, you want to find a plate with how
many colonies: Answer: 30-300
◉The main idea for doing this lab is to: Answer: Make a standard curve
plot
◉In which of the following foods would you normally expect to find a
high number of bacteria? Answer: Yogurt
,◉Where would you expect to find members of the genus Pseudomonas?
Answer: In the soil
◉Where would you be most likely to find the fungus Penicillium?
Answer: In soils and waters
◉Where would you be most likely to find members of the genera
Escherichia? Answer: In the guts of mammals
◉How does bacterial enumeration help to determine if a food is safe for
consumption? Answer: This will give a general idea of the quality of the
food.
◉In which of the following food types would you expect to see high
numbers of microbes? Answer: Cheese
◉What does the presence of enteric organisms in milk indicate?
Answer: Fecal contamination of the milk occurred somewhere in the
production process.
◉Which of the following terms best describes the enumeration of
bacteria as described in your lab? Answer: A direct enumeration
, ◉You found 67 colonies on the ground beef plate with the 10^-2
dilution. What is the concentration of bacteria per milliliter of beef?
Answer: 6.7 × 10^3 CFU/ml
◉Which of the following is indicative of the presence of E. coli?
Answer: colonies on EMB agar with a metallic sheen
◉If you had fresh lettuce containing 9.3 × 10^3 organisms/ml, how
many colonies would you expect to see on a plate that represents a 10^-2
dilution? Answer: 93
◉Which of the following bacterial concentrations would produce a
TFTC plate at the 10^-4 dilution? Answer: 2 × 10^5 organisms/ml
◉Which of the following would produce a countable plate? Answer: A
solution containing 1.9 × 104 at a 10-2 dilution
◉After running this experiment, you find that the carrots you tested had
only 15 bacteria/ml. Your lab partner states that this number is so low
that the carrots do not need further treatment. Why should you disagree?
Answer: A low number of organisms does not indicate the absence of
pathogens.
