VTPB 334 Lab Exam – Key Concepts and Study
Guide Final Edition.
1. Which biosecurity practices are practical to implement in your lab or practice
without slowing down productivity?
A) Full disinfection after each sample
B) Balance between protection and practicality
C) Goal is to break the chain of infection to reduce outbreak risk
D) Ensure vectors (people, rodents, wild birds) are cleaned or removed
Answer>>>: : B, C, D .
2. What are the main transmitters of microbes?
A) Birds
B) Vectors
C) Fomites
Answer>>>: : A, B, C .
3. True or False: Organic material can alter the effectiveness of disinfectants.
Answer>>>: : True .
4. Which of the following statements regarding disinfectants is FALSE?
A) They kill all microbes instantly
B) Effectiveness is not affected by organic matter
C) All statements are correct
Answer>>>: : A, B
Page 1 of 24
,VTPB 334 Lab Exam – Key Concepts and Study
Guide Final Edition.
5. Why should eggs be sprayed with 70% ethanol before inoculation?
Answer>>>: : To disinfect the eggshell surface .
Section B: Dilutions & Microbiology Calculations
6. Simple dilution: Make 5 L of 70% ethanol from 90% ethanol. What is V1?
Given: C1 = 90%, V2 = 5 L, C2 = 70%
Answer>>>: : 3889 mL .
7. You made a 2-fold serial dilution into 5 tubes. The first tube has 50%
concentration. What is the concentration of the 5th tube?
Answer>>>: : 0.03125 (1/32) .
8. A simple dilution is defined as:
Answer>>>: : A dilution in which a volume of a liquid material is combined
with an appropriate volume of solvent to achieve the desired concentration .
9. Given a total volume of 1 mL (diluent + virus) for a 10-fold serial dilution, what
volume of virus suspension is transferred at each step?
Answer>>>: : 100 µL .
Section C: Microscopy
10. Which objective is best for viewing fungus under the microscope?
Answer>>>: : Blue / 40X .
Page 2 of 24
, VTPB 334 Lab Exam – Key Concepts and Study
Guide Final Edition.
11. Which of the following statements about microscopes is FALSE?
A) The light source should always be at its brightest for all samples
B) Objectives must be cleaned after each use
Answer>>>: :A
12. What is the correct order for Diff-Quik staining?
Answer>>>: : Alcohol fixative → Solution 1 → Solution 2 .
13. When cleaning immersion oil from microscope objectives, which objective do
you clean last and why?
Answer>>>: : Clean the 100x objective last to avoid transferring immersion
oil to other objectives .
14. True or False: Radial Immunodiffusion (RID) agar contains antibodies, and the
unknown sample contains antigens.
Answer>>>: : True .
15. What is the correct order of stains for the Gram stain?
Answer>>>: : Crystal violet → Gram’s iodine → Acetone alcohol → Safranin
.
16. True or False: Slide smear preparation from solid and broth media requires a
drop of DI water.
Answer>>>: : True .
Page 3 of 24
Guide Final Edition.
1. Which biosecurity practices are practical to implement in your lab or practice
without slowing down productivity?
A) Full disinfection after each sample
B) Balance between protection and practicality
C) Goal is to break the chain of infection to reduce outbreak risk
D) Ensure vectors (people, rodents, wild birds) are cleaned or removed
Answer>>>: : B, C, D .
2. What are the main transmitters of microbes?
A) Birds
B) Vectors
C) Fomites
Answer>>>: : A, B, C .
3. True or False: Organic material can alter the effectiveness of disinfectants.
Answer>>>: : True .
4. Which of the following statements regarding disinfectants is FALSE?
A) They kill all microbes instantly
B) Effectiveness is not affected by organic matter
C) All statements are correct
Answer>>>: : A, B
Page 1 of 24
,VTPB 334 Lab Exam – Key Concepts and Study
Guide Final Edition.
5. Why should eggs be sprayed with 70% ethanol before inoculation?
Answer>>>: : To disinfect the eggshell surface .
Section B: Dilutions & Microbiology Calculations
6. Simple dilution: Make 5 L of 70% ethanol from 90% ethanol. What is V1?
Given: C1 = 90%, V2 = 5 L, C2 = 70%
Answer>>>: : 3889 mL .
7. You made a 2-fold serial dilution into 5 tubes. The first tube has 50%
concentration. What is the concentration of the 5th tube?
Answer>>>: : 0.03125 (1/32) .
8. A simple dilution is defined as:
Answer>>>: : A dilution in which a volume of a liquid material is combined
with an appropriate volume of solvent to achieve the desired concentration .
9. Given a total volume of 1 mL (diluent + virus) for a 10-fold serial dilution, what
volume of virus suspension is transferred at each step?
Answer>>>: : 100 µL .
Section C: Microscopy
10. Which objective is best for viewing fungus under the microscope?
Answer>>>: : Blue / 40X .
Page 2 of 24
, VTPB 334 Lab Exam – Key Concepts and Study
Guide Final Edition.
11. Which of the following statements about microscopes is FALSE?
A) The light source should always be at its brightest for all samples
B) Objectives must be cleaned after each use
Answer>>>: :A
12. What is the correct order for Diff-Quik staining?
Answer>>>: : Alcohol fixative → Solution 1 → Solution 2 .
13. When cleaning immersion oil from microscope objectives, which objective do
you clean last and why?
Answer>>>: : Clean the 100x objective last to avoid transferring immersion
oil to other objectives .
14. True or False: Radial Immunodiffusion (RID) agar contains antibodies, and the
unknown sample contains antigens.
Answer>>>: : True .
15. What is the correct order of stains for the Gram stain?
Answer>>>: : Crystal violet → Gram’s iodine → Acetone alcohol → Safranin
.
16. True or False: Slide smear preparation from solid and broth media requires a
drop of DI water.
Answer>>>: : True .
Page 3 of 24
