MCQs on Buffer Solutions
1. What is the pH range of an acidic buffer solution?
A) pH > 7
B) pH < 7 ✅
C) pH = 7
D) pH = 0
Correct Answer: B) pH < 7
2. Which of the following is used to prepare an acidic buffer?
A) Weak acid + salt of a strong base ✅
B) Strong acid + salt of a weak base
C) Weak base + salt of a strong acid
D) Weak acid + weak base
Correct Answer: A) Weak acid + salt of a strong base
3. What is the primary function of a buffer solution?
A) To maintain a constant pH
B) To increase pH when acidic substances are added
C) To decrease pH when basic substances are added
D) To neutralize both acid and base
Correct Answer: A) To maintain a constant pH
4. Which of the following is an example of an alkaline buffer?
A) Sodium acetate + acetic acid
B) Ammonium hydroxide + ammonium chloride ✅
C) HCl + NaOH
D) H2PO4- + HPO4^2-
Correct Answer: B) Ammonium hydroxide + ammonium chloride
MCQs on Microscopy and Hemocytometer
5. What is the purpose of using a hemocytometer in cell counting?
A) To measure the pH of the solution
B) To count the number of cells in a sample ✅
C) To prepare a buffer solution
D) To sterilize cells
Correct Answer: B) To count the number of cells in a sample
6. Which stain is commonly used to assess the viability of yeast cells?
A) Methylene Blue ✅
B) Crystal Violet
C) Iodine
D) Safranin
Correct Answer: A) Methylene Blue
7. Which part of the microscope is responsible for focusing light onto the specimen?
A) Eyepiece
B) Objective lens
C) Condenser ✅
D) Mechanical stage
Correct Answer: C) Condenser
8. Which objective lens of a microscope has the highest magnification?
A) Low power (10x)
B) Medium power (20x)
C) High dry (40x)
D) Oil immersion (100x) ✅
Correct Answer: D) Oil immersion (100x)
9. What is the function of the iris diaphragm in a microscope?
A) To adjust the magnification
B) To focus the image
C) To control the amount of light entering the microscope ✅
D) To hold the specimen in place
Correct Answer: C) To control the amount of light entering the microscope
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MCQs on Buffer Solutions
10. Which of the following statements is true for an alkaline buffer solution?
A) pH < 7
B) It is made by mixing a weak base with a strong base
C) pH > 7 ✅
D) It is made by mixing a strong acid and a strong base
Correct Answer: C) pH > 7
11. What is the pH of the phosphate buffer solution prepared from HPO4^2- and
H2PO4-?
A) 4.0
B) 5.6
C) 7.4 ✅
D) 9.25
Correct Answer: C) 7.4
12. What is the function of NaOH or HCl in buffer preparation?
A) To neutralize the solution
B) To adjust the final pH ✅
C) To prepare a buffer solution
D) To enhance the buffer capacity
Correct Answer: B) To adjust the final pH
13. Which of the following buffers is most commonly used in biochemical and
physiological experiments?
A) Acetate buffer
B) Phosphate buffer ✅
C) Citrate buffer
D) Carbonate buffer
Correct Answer: B) Phosphate buffer
MCQs on Microscopy and Hemocytometer
14. What is the most commonly used microscope in microbiological laboratories?
A) Fluorescent microscope
B) Electron microscope
C) Compound light microscope ✅
D) Phase contrast microscope
Correct Answer: C) Compound light microscope
15. What is the term for the ability of a microscope to distinctly separate closely related
objects?
A) Magnification
B) Focal length
C) Resolving power ✅
D) Numerical aperture
Correct Answer: C) Resolving power
16. In a light microscope, what part is responsible for carrying the objective lenses?
A) Eyepiece
B) Revolving nosepiece ✅
C) Stage clips
D) Sub-stage condenser
Correct Answer: B) Revolving nosepiece
17. What is the main advantage of using an oil immersion lens?
A) Increased contrast
B) Increased resolution ✅
C) Increased magnification
D) Improved color visibility
Correct Answer: B) Increased resolution
18. What is the proper way to prepare a hemocytometer for use?
A) Clean with soap and water
B) Clean with 70% ethanol ✅
C) Clean with distilled water
D) Clean with methylene blue
Correct Answer: B) Clean with 70% ethanol
MCQs on Cell Counting and Viability Testing
19. What is the main purpose of using methylene blue in yeast cell viability testing?
A) To stain the cell walls
B) To inhibit cell growth
C) To differentiate between live and dead cells ✅
D) To stain the cell nucleus
Correct Answer: C) To differentiate between live and dead cells
20. What is the dilution factor when 10 microliters of yeast suspension is mixed with 10
microliters of methylene blue?
A) 1
B) 10
C) 100
D) 2 ✅
Correct Answer: D) 2
21. When using a hemocytometer, which squares should be counted for large cells?
A) Only the central square
B) The four corner squares and the central square ✅
C) Only the central smaller squares
D) The middle square and outer small squares
Correct Answer: B) The four corner squares and the central square
22. How should you count cells in a hemocytometer if they overlap the exterior line of a
large square?
A) Count them twice
B) Do not count overlapping cells
C) Only count cells on the top or right-hand line of the square ✅
D) Only count cells touching the bottom or left-hand side
Correct Answer: C) Only count cells on the top or right-hand line of the square
Practical No: 4 – Preparation of Buffers
MCQs on Buffer Solutions and Their Preparation
1. What is the main characteristic of a buffer solution?
A) It changes the pH drastically when an acid or base is added
B) It resists pH changes upon the addition of acidic or basic components ✅
C) It maintains a neutral pH
D) It only works at a pH of 7
Correct Answer: B) It resists pH changes upon the addition of acidic or basic
components
2. Which of the following best describes an acidic buffer solution?
A) It is made by mixing a weak base with its salt
B) It is made by mixing a weak acid with its salt ✅
C) It has a pH greater than 7
D) It is made by mixing a strong acid and a weak base
Correct Answer: B) It is made by mixing a weak acid with its salt
3. What is the pH range for an acidic buffer solution?
A) pH > 7
B) pH < 7 ✅
C) pH = 7
D) pH = 5.6
Correct Answer: B) pH < 7
4. Which of the following is an example of an alkaline buffer solution?
A) Sodium acetate and acetic acid
B) Ammonium hydroxide and ammonium chloride ✅
C) Phosphate buffer
D) Sodium citrate and citric acid
Correct Answer: B) Ammonium hydroxide and ammonium chloride
5. The pH of an alkaline buffer solution is:
A) pH < 7
B) pH = 7
C) pH > 7 ✅
D) pH = 5.8
Correct Answer: C) pH > 7
6. To prepare a phosphate buffer with a pH of 7.4, which of the following is used?
A) NaH2PO4 and Na2HPO4 ✅
B) HCl and NaOH
C) Sodium acetate and acetic acid
D) Ammonium chloride and ammonium hydroxide
Correct Answer: A) NaH2PO4 and Na2HPO4
7. What is the primary purpose of adjusting the pH in buffer preparation?
A) To dilute the solution
B) To maintain a stable pH ✅
C) To increase the concentration of the buffer
D) To increase the buffer capacity
Correct Answer: B) To maintain a stable pH
8. Which of the following buffer solutions has a pH range from 5.8 to 7.4?
A) Citrate buffer
B) Acetate buffer
C) Phosphate buffer ✅
D) Carbonate buffer
Correct Answer: C) Phosphate buffer
Practical No: 5 – Use of Simple and Compound Microscope and Micrometry
MCQs on Microscopy
9. What is the main purpose of a compound microscope?
A) To view objects that cannot be seen with the naked eye ✅
B) To measure the size of the object
C) To provide a three-dimensional view of the object
D) To measure the depth of the object
Correct Answer: A) To view objects that cannot be seen with the naked eye
10. What is the magnifying power of a microscope determined by?
A) The focal length of the lenses
B) The numerical aperture of the lenses
C) The product of the magnifications of the objective and eyepiece lenses ✅
D) The amount of light passing through the object
Correct Answer: C) The product of the magnifications of the objective and eyepiece
lenses
11. Which type of microscope is commonly used in microbiological laboratories to view
stained specimens?
A) Fluorescent microscope
B) Bright field microscope ✅
C) Phase contrast microscope
D) Electron microscope
Correct Answer: B) Bright field microscope
12. What is the role of the iris diaphragm in a microscope?
A) To focus light onto the object
B) To adjust the magnification
C) To control the amount of light entering the microscope ✅
D) To adjust the position of the condenser
Correct Answer: C) To control the amount of light entering the microscope
13. Which objective lens is typically used for high magnification in a compound
microscope?
A) 10x objective lens
B) 40x objective lens ✅
C) 20x objective lens
D) 5x objective lens
Correct Answer: B) 40x objective lens
14. The numerical aperture (NA) of a microscope is related to:
A) The total magnification
B) The resolving power of the microscope ✅
C) The light intensity
D) The total light source
Correct Answer: B) The resolving power of the microscope
Practical No: 6 – Enumeration of Bacteria/Yeast Cells through Hemocytometer
MCQs on Hemocytometer and Cell Counting
15. What is the primary purpose of a hemocytometer?
A) To view the shape of the cells
B) To count the number of cells in a given volume ✅
C) To differentiate between dead and living cells
D) To measure the volume of a cell
Correct Answer: B) To count the number of cells in a given volume
16. Which of the following is true when counting cells on a hemocytometer?
A) Count cells that overlap the bottom and left lines only
B) Count cells that overlap the top and right lines ✅
C) Count all cells even if they overlap the lines
D) Ignore cells that are on the grid lines
Correct Answer: B) Count cells that overlap the top and right lines
17. How are live and dead yeast cells distinguished using methylene blue?
A) Live cells turn blue and dead cells remain colorless
B) Dead cells turn blue and live cells remain colorless ✅
C) Both live and dead cells appear blue
D) Both live and dead cells remain colorless
Correct Answer: B) Dead cells turn blue and live cells remain colorless
18. What is the purpose of using a 0.01% methylene blue solution in yeast viability
testing?
A) To kill the cells
B) To prevent cells from settling in the hemocytometer
C) To distinguish between live and dead yeast cells ✅
D) To stain the yeast cells for better visibility
Correct Answer: C) To distinguish between live and dead yeast cells
19. What is the dilution factor when 10 microliters of yeast suspension is mixed with 10
microliters of methylene blue?
A) 2 ✅
B) 5
C) 1
D) 0.5
Correct Answer: A) 2
20. What magnification is typically used when counting cells in a hemocytometer?
A) 10x
B) 50x
C) 100x ✅
D) 200x
Correct Answer: C) 100x
21.MCQs on Practical No. 7: Preparation of Washed Bacterial Cell
Suspension using Centrifuge
22. 1. What is the principle behind centrifugation?
A) Separation of molecules based on their size
B) Separation of molecules based on their density
C) Separation of molecules based on their color
D) Separation of molecules based on their temperature
✅ Correct Answer: B) Separation of molecules based on their density
23. 2. What is the unit of measurement for the speed of a centrifuge?
A) Relative Centrifugal Force (RCF)
B) Revolutions Per Minute (RPM)
C) Kilograms per meter (kg/m)
D) Centimeters per second (cm/s)
✅ Correct Answer: B) Revolutions Per Minute (RPM)
24. 3. What does the Relative Centrifugal Force (RCF) measure?
A) The speed of rotation of the centrifuge
B) The gravitational force applied to the sample
C) The temperature inside the centrifuge
D) The volume of the centrifuge tube
✅ Correct Answer: B) The gravitational force applied to the sample
25. 4. What is the first step in preparing a bacterial suspension using a centrifuge?
A) Add cell suspension to an Eppendorf tube
B) Incubate the bacterial culture
C) Prepare liquid LB media
D) Centrifuge the bacterial suspension at 3000rpm
✅ Correct Answer: C) Prepare liquid LB media
26. 5. After the first centrifugation step in the protocol, what is done to the bacterial
pellet?
A) It is directly used in experiments
B) It is washed with 1x PBS
C) It is incubated for 12-18 hours
D) It is stored at -20°C
✅ Correct Answer: B) It is washed with 1x PBS
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28.MCQs on Practical No. 8: Demonstration of Different Sterilization
Techniques
29. 1. What is sterilization defined as?
A) Killing of all harmful microorganisms
B) Total destruction of all microorganisms and their spores
C) Destruction of only pathogenic microorganisms
D) Removal of visible dirt from surfaces
✅ Correct Answer: B) Total destruction of all microorganisms and their spores
30. 2. Which sterilization method uses heat in the form of steam under pressure?
A) Dry heat sterilization
B) Boiling
C) Autoclaving
D) Pasteurization
✅ Correct Answer: C) Autoclaving
31. 3. What temperature is required for autoclaving to kill bacterial spores?
A) 100°C
B) 110°C
C) 121°C
D) 130°C
✅ Correct Answer: C) 121°C
32. 4. Which method is most commonly used for sterilizing glassware and metallic
devices?
A) Autoclaving
B) Flaming
C) Hot air oven
D) Boiling
✅ Correct Answer: B) Flaming
33. 5. What is the principle behind the chemical method of sterilization?
A) Use of high temperature to destroy microorganisms
B) Use of chemical bactericidal agents to kill microorganisms
C) Removal of microorganisms using mechanical filters
D) Use of radiation to sterilize equipment
✅ Correct Answer: B) Use of chemical bactericidal agents to kill microorganisms
34. 6. Which of the following is a gaseous sterilization method?
A) Ethylene oxide (EO)
B) Hydrogen peroxide
C) Glutaraldehyde
D) Chlorine
✅ Correct Answer: A) Ethylene oxide (EO)
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