This set of Fermentation Technology Multiple Choice Questions & Answers (MCQs) focuses on “Filter Sterilization”.
1. Which of the following is the method of filter sterilization?
a) Osmosis
b) Diffusion
c) Double Diffusion
d) Sitting Drop
View Answer
Explanation: Diffusion is the method of filter sterilization. The other mechanisms include Inertial impaction, Electrostatic attraction, Interception. Suspended particles are separated from the fluid by these mechanisms.
2. In which of the following the large aerosol particles are deposited on the walls of airway conduit?
a) Inertial Impaction
b) Diffusion
c) Electrostatic attraction
d) Interception
View Answer
Explanation: The large aerosol particles are deposited on the walls of airway conduit in inertial impaction. The impaction occurs where the airway changes. It is more significant in the filtration of gases than in the filtration of liquids.
3. Brownian motion occurs in ___________
a) Inertial Impaction
b) Diffusion
c) Electrostatic attraction
d) Interception
View Answer
Explanation: Brownian motion occurs in diffusion. The small particles in the fluid exhibit Brownian motion which is a random zig-zag motion of solid particles in the fluid. Diffusion is more significant in the filtration of gases than in the filtration of liquids.
4. In which of the following the oppositely charged particles are attracted?
a) Inertial Impaction
b) Diffusion
c) Electrostatic attraction
d) Interception
View Answer
Explanation: The electrostatic attraction occurs in which the oppositely charged particles are attracted to each other and the suspended solids thus get filtered out. Hence, the medium gets sterilized by filtration.
5. The optimum temperature for pasteurisation is _____________
a) 62°C – 65°C
b) 60°C – 65°C
c) 62°C – 72°C
d) 65°C – 75°C
View Answer
Explanation: The optimum temperature for Pasteurization is 62°C – 72°C. It was discovered by Louis Pasteur and hence termed after him. It is a process to eliminate the pathogens from milk or milk products.
6. The particles which are larger than the filter pores are removed by ________
a) Inertial Impaction
b) Diffusion
c) Electrostatic attraction
d) Interception
View Answer
Explanation: The particles which are larger than the filter pores are removed by direct interception. Even if there are smaller particles, they are also retained by interception. It is an important mechanism in the filtration of gases as well as the filtration of liquids.
7. Which of the following filters is the most commonly used?
a) Nitrocellulose
b) Filter paper
c) Sieve tubes
d) Cellophane
View Answer
Explanation: Nitrocellulose filters are the most commonly used filters. Nitrocellulose papers are made up of negatively charged. The medium which is to be filtered contains positively charged particles which are attracted by negatively charged cellulose. Thus the filtration occurs by direct interception.
8. What is the pore size of the nitrocellulose?
a) 0.25 µ
b) 0.28 µ
c) 0.22 µ
d) 0.20 µ
View Answer
Explanation: The pore size of the nitrocellulose filter is 0.22 µ. They are the most commonly used filters in filtration sterilization. It has a powerful binding technique and is also used to study DNA-protein interactions.
9. The heat reactive medium can be sterilized best by _____________
a) Continuous sterilization
b) Batch sterilization
c) Filter sterilization
d) Heat sterilization
View Answer
Explanation: The medium which is reactive to heat and is heat-labile can be sterilized best by filter sterilization as it does not involve heating of the medium. Batch sterilization, Continuous sterilization, Heat sterilization involve the heating of medium to sterilize it.
10. Non-Fixed filters are also called as absolute filters.
a) True
b) False
View Answer
Explanation: The Non-Fixed filters are also called as depth filters. They remove the particle by inertial impaction, diffusion, electrostatic interaction. It does not rely on Interception. Non-Fixed filters do not have a fixed pore size.
11. Which of the following is not an example of depth filters?
a) PTFE membranes
b) Glass fiber
c) Cotton
d) Sintered Metals
View Answer
Explanation: The PTFE (Poly Tetra Fluoro Ethane) is an example of an absolute filter. Whereas the glass fibers, cotton, sintered metals are used as depth filters or non-fixed filters.
12. The absolute filters have fixed-pore size.
a) True
b) False
View Answer
Explanation: The absolute filters have varying pore sizes. They are constructed that the filtration medium will not get distorted. The size of the pore is controlled during the manufacture of absolute filters.
13. Which of the following cannot be sterilized by steam?
a) Air
b) Water
c) Fermenter vessels
d) Fermentation media
View Answer
Explanation: Air cannot be sterilized by steam. It can be sterilized by heat, filtration, UV radiation, gas scrubbing. The sterilization by heat and filtration the most common method used for air sterilization.
14. Which of the following is a typical aeration rate for aerobic fermentation?
a) 0.5 – 2 vvm
b) 1 – 2 vvm
c) 0.1 – 0.5 vvm
d) 3 – 4 vvm
View Answer
Explanation: The typical aeration rate for aerobic fermentation is 0.5 – 2.0 vvm. Here, the first v stands for volume of air in liter. The second v stands for per unit of medium and m stands for per unit time in minutes.
15. 1% of phenol acts as ___________
a) Antiseptic
b) Disinfectant
c) Antibiotics
d) Antigen
View Answer
Explanation: 1% of phenol acts as a disinfectant. Disinfectants are commonly used for killing or inhibiting bacterial growth. That is why phenolic compounds are used for chemical sterilization. 0.5% of phenol acts antiseptics.
Sanfoundry Global Education & Learning Series – Fermentation Technology.
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