BIOL 260
Lab Practicum-study guide
Review your lab quizzes and lab reports to prepare for the lab final. This study guide is intended
to help you review some of the big concepts in each of the labs.
Ubiquity (Lab 1)
1. What type of media did we use for this experiment?
2. What organisms can you expect to grow at 37oC, at room temperature (25oC)
3. How can you tell the difference from fungi (molds) and bacteria on an agar plate?
Microscope (Lab 3)
1. Know the parts of the microscope and their function.
2. How do you adjust the scope top look at live organisms? at bacteria?
3. Which lens is the oil immersion lens? When would you use it?
4. Know how to determine the magnification (total) of the image.
Simple Stains (Lab 5)
1. How do you make a smear from broth/slant culture?
2. Why do you heat fix a slide?
3. What does a simple stain tell you about an organism?
Differential and Selective Stains (Gram Stain) (Lab 6)
1. Know the steps of the gram stain.
2. What can cause gram (+) cells to appear gram (-)?
3. What color are gram (+) and gram (-) cells?
4. What does the gram stain tell you about an organism?
5. Why is it important to use fresh cultures for the gram stain?
6. Why can’t you gram stain acid fast organisms?
7. What does an endospore look like when gram stained? When endospore stained?
Pure Culture and Aseptic Technique (Lab 2)
1. What is aseptic technique? What is meant by a pure culture?
2. Why is it important in microbiology?
3. Why do you streak cultures for isolation?
4. Know how to inoculate a broth, slant, and a deep.
5. Know the technique for streaking a plate. You may need to do this on the test.
Chemically defined, Complex, and Selective, and Differential Media (Lab 7)
1. Understand the difference between defined, undefined (complex), selective, and differential
media.
2. What type of media is TSA, Glucose Salts agar, EMB?
3. Know what types of organisms you can expect to grow on each of the plates used in this
exercise. What types of organisms are inhibited?
Quantification of Microorganisms (Lab 8)
1. Know how to determine the number of organisms in a culture (use the formula).
2.
3.
4.
Know how to calculate the dilution of a sample within an individual tube.
Why is it necessary to dilute the culture?
What are the parameters for choosing a plate within a series to do the calculations?
Aerobic/Anaerobic Growth (Lab 9)
1. What was the purpose of this lab?
2. Understand the difference between aerobic, anaerobic, facultative organisms.
3. Be able to identify the type of organism growing in a shake/agar deep tube.
4. Why were shake tubes used for this exercise and not agar plates or broth?
UV light (Lab 12)
1. What effect does UV light have on bacteria?
2. Be able to read a series of plates that have been exposed to UV light. What can you use as a
control?
3. What types of organisms should be more resistant to UV light? More sensitive?
Antibiotics (Lab 14)
1. What are antibiotics?
2. What are the clear zones around the antibiotic discs called?
3. What does the Kirby-Bauer test tell you about an organism?
4. How do you determine antibiotic resistance or sensitivity of the organism?
5. What relationship did you find between the gram stain of an organism and its susceptibility
to an antibiotic?
Antiseptics and Disinfectants (Lab 15)
1. What are antiseptics? What are disinfectants?
2. What relationship did you find between the gram stain of an organism and its susceptibility
to an antiseptic or disinfectant?
3. How did we determine how effective the antiseptic or disinfectant was towards an
organism?
Transformation (Lab 17)
1. What was the purpose of this lab?
2. What is transformation?
3. What was the source of the DNA?
4. What were the positive controls used in the lab? Why are they important?
5. Which combination on the plates demonstrated the actual transformation?
6. How did you determine if transformation actually occurred?
Normal Skin biota (Lab 22)
1. What types of organisms were we looking for in this exercise?
2. Why did we incubate some plates in the anaerobic chamber?
3. What types of organisms could grow on both the aerobic and anaerobic plate? Which
organisms on the skin grew only on the aerobic plate? What is the gram reaction of each?
4. Why did we use a shake/melted agar deep tube?
5. What does a (+) glucose brom cresol purple slant look like? What does a positive test tell
you about the organism?
6.
6.
What types of organisms grow on Mannitol Salt Agar? What can you determine about an
organism that grows on a MSA plate?
How did you determine the species of Staphylococcus?
Streptococci and Respiratory Microbes (Lab 23)
1. What types of organisms are normal biota of the throat? What type of agar was used to grow
the throat flora?
2. Be able to identify the different types of hemolysis on a blood agar plate.
3. What type(s) of hemolysis are considered normal flora? potential pathogens?
4. What does a (+) bile esculin and (+) salt broth test look like? What kind of organism can
grow on the bile esculin slant and the salt broth?
5. What is the catalase test? The oxidase test?
6. How do you distinguish between the Staphylococcus and Streptococcus genera? (What test
differentiates them?)
Identification of Enteric Gram Negative rods (Lab 24)
1. What color is a (+) phenol red fermentation test? What does a (+) test tell you about the
organism?
2. What is the indicator in the phenol red fermentation test? What does it indicate?
3. What does the durham tube tell you?
4. Understand the significance between the MR and VP tests.
5. Be able to read a positive and negative test for each of the biochemical tests used in this lab.
6. Know whether or not you need to add a reagent to the test. Are there any pH indicators?
7. Understand what each test is telling you about the organism.
8. Know whether the agar plates used in this lab are selective, differential, or both. What does
growth on the plates indicate? (review the MacConkey, HE, and XLD plates)
Water test (Lab 29)
1. Be able to interpret an MPN test - which lactose tubes are positive?
2. What is the MPN index?
3. Why do you plate (+) BGLB tubes onto LES Endo plates?
4. Be able to interpret a culture growing on an LES Endo plate.
5. What are the indicator organisms we are looking for in this lab? What are the characteristics
of this group of organisms?