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GATE

HELPLINE

BIOPROCESS

ENGINEERING

MCQs-III

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21. Measurement of KLa in a bioreactor can be carried out by sodium sulfite oxidation method that

is based on the oxidation of sodium sulfite solution containing 0.003 M Cu++

ions and the air was

sparged in. After 10 minute the air flow was stopped and a 10 ml sample was taken and titrated.

The concentration of the sodium sulfate in the sample was found to be 0.20 M. the oxygen

uptake rate for this aerated system will work out to be:

a) 0.08 g l-1

s-1

c) 0.8 g l-1

s-1

b) 0.008 g l-1

s-1

d) none of the above

22. Examine the date given below in the table on purification of a protein X

Step Volume Protein Enzyme activity

Crude cell free extract 500 12.0 5.0

Ammonium sulfate precipitation 125 3.0 11.0

Ion exchange chromatography 10 9.0 75.0

The yield percent and purification factor respectively at the end of the experiment will be approximately

a) 25 and 3 c) 20 and 30

b) 75 and 30 d) 30 and 20

23. Which one of the following reactions is used for the purpose of recycling enzymes in

bioprocesses?

a) Isomerization c) Phosphorylation

b) Polymerization d) Immobilization

24. To optimize the bioreactor system, which one of the following conditions is least important for

anaerobic fermentation?

a) Culture agitation to maintain oxygen supply

b) Restriction of the entry of contaminating organisms

c) Control of parameters like pH and temperature

d) Maintenance of constant culture volume

25. Power number, also Newton’s number. Is defined as a dimensionless parameter relating to

a) Turbulent flow

b) The relative velocity between the nutrient solution and individual cells

c) Energy required by the stirred reactors

d) None of the above

26. The selection of the appropriate purification method in the product recovery after microbial

fermentation depends on the

a) Nature and the stability of the end products produced

b) Type of the side products present

c) Degree of purification required

d) All of the above

27. Which of the following techniques is NOT ideal for immobilizing cell- free enzymes?

a) Physical entrapment by encapsulation

b) Covalent chemical bonding to surface carriers

c) Physical bonding by flocculation

d) Covalent chemical bonding by cross linking the precipitate

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28. If the fractional recovery at each step of unit operation is 0.8, the recovery after 4 step will be

a) 0.24 c) 0.41

b) 3.23 d) 0.82

29. The factors likely to increase the rate of reaction catalyzed by a surface immobilized enzyme

is/are

a) Increased agitation of the bulk liquid containing the substrate

b) Continued replacement of the bulk liquid containing the substrate

c) Increased concentration of the substrate in the bulk liquid

d) All of the above

30. Which of the following cases are likely to lead to faster rates of catalysis by an enzyme

immobilized on a negatively charged support?

a) A positively charged substrate and a negatively charged product

b) A negatively charged substrate and a positively charged product

c) A positively charged substrate and a positively charged product

d) None of the above

31. Which of the following statements applies to the operation of a fed batch process?

a) The volume of the culture increases with time

b) It helps controlling repressive effects of the nutrient being fed

c) It eliminates the need for oxygen supply

d) Only (A) and (B) of the above

32. In large scale fermentation, the preferred method of sterilization is

a) Chemicals c) radiation

b) Filtration d) heat

33. In secondary metabolism two distinct – trophophase and idiophase refer respectively to

a) Growth and production phase

b) Early and late phase

c) Primary and secondary metabolism

d) Lag phase and log phase

34. Which of the following is true for chemostat?

a) Concentration of limiting substrate is maintained constant

b) High productivity can not be achieved

c) Automation is difficult

d) Mutation is less likely to occur

35. For scaling up of a bioreactor, the following parameter is assumed to be constant

a) Airflow rate

b) Diameter of the impeller

c) Agitator speed

d) Volumetric mass transfer coefficient

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36. Mechanism of separation of contaminants present in air by fibrous media are

a) Interception

b) Inertial impaction

c) Diffusion

d) All the above