GATE HELPLINE BIOPROCESS ENGINEERING MCQs-I

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1. Diauxic patter of the biomass growth is associated with P) Multiple lag phases Q) Sequential utilization of multiple substrates R) Simultaneous utilization of multiple substrates S) Absence of lag phase a) P,R c) R,S b) P,Q d) Q,S 2. Match the following P) Sedimentation coefficient Q) Partition coefficient R) Rejection coefficient S) Activity coefficient a) P-3, Q-1, R-4, S-2 b) P- 4, Q-3, R-1, S-2

1. Aqueous two-phase extraction 2. Ultracentrifugation 3. Dialysis 4. Centrifugation c) P-2, Q-1, R-4, S-3 d) P-4, Q-1, R-2, S-3

3. Match the following A) Marine type impeller B) Draft tube C) Diaphragm valve D) Sparger a) A-4, B-2, C-1, D-3 b) A-3, B-4, C-2, D-1

1. Recirculation of medium 2. Aeration of medium 3. Animal cell cultivation 4. Sterile operation c) A-3, B-1, C-4, D-2 d) A-2, B-1, C-4, D-3

4. In a chemostat, evaluation the dilution rate at the cell wash out condition by applying monod’s model with the given set of data µmax = 1 h-1; YX/S = 0.5gg-1 ; Ks = 0.2 gL-1 ; S0 = 10g L-1 a) 1.00 h-1 c) 0.98 h-1 b) 0.49 h-1 d) 1.02 h-1 By the given data: µmax = 1 h-1 maximum growth rate -1 Ks = 0.2 gL monods constant -1 S0 = 10g L initial substrate concentration The dilution rate at wash out condition is Dcrit=? Dcrit= µmax S0/ (Ks+ S0) Substituting the values in equation This is copyrighted product of GATEHELPLINE

We get 0.98 hr-1 5. A bacterial culture with an approximate biomass composition of CH1.8O0.5N0.2 is grown aerobically on a defined medium containing glucose as the sole carbon source and ammonia being the nitrogen source. In this fermentation, biomass is formed with a yield coefficient of 0.35 gram dry cell weight per gram of glucose and acetate is produced with a yield coefficient of 0.1 gram acetate per gram of glucose. The respiratory coefficient for the above culture will be a) 0.90 c)1.00 b) 0.95 d)1.05 6. A bacterial culture having a specific oxygen uptake rate of 5 mmol O2 (g-DCW)-1 hr -1 is being grown aerobically in a fed- batch bioreactor. The maximum value of the volumetric oxygen transfer coefficient is 0.18s-1 for the stirred tank bioreactor and the critical dissolved oxygen concentration is 20% of the saturation concentration (8 mg/ml). the maximum density to which the cells can be grown in the fed-batch process without the growth being limited by oxygen transfer is approximately a) 14 g/l c) 32 g/l b) 26 g/l d) 65 g/l A double reciprocal plot was created from the specific growth rate and limiting substrate concentration data obtained from a chemostat experiment. A linear regression gave of 1.25 hr and 100 mg-hr-1 for the intercept and slope, respectively. 7. The respective values of the Monod kinetic constants µm (hr-1) and Ks (mg/l) are as follows: a) 0.08,8 c) 0.8,80 b) 0.8,0.8 d) 8,8 Solution: Intercept = 1.25 hr Slope = 100 mg hr l-1 Now we have to find the maximum growth rate and Monod’s constant From the reciprocal plot of Monod’s equation 1/µ= Ks/ µm*1/S+1/ µm Y=mX+C C = intercept = 1/ µm => 1.25 = 1/ µm => µm = 0.8 m = slope = Ks/ µm=> 100= Ks/ µm=> 100*0.8=Ks => Ks = 80

8. The same culture (with the µm and Ks values as computed above) is cultivated in a 10-litre chemostat being operated with a 50 ml/min sterile feed containing 50g/l of substrate. Assuming an overall yield coefficient of 0.3 g-DCW / g- substrate, the respective values of the outlet biomass and substrate concentrations are a) 15 g/L, 48 mg/L c) 15g/L, 0.48 g/L b) 48 g/L,15 g/L d) 4.8 g/L, 4.8 g/L This is copyrighted product of GATEHELPLINE

Solution: Given data is some for above problem & hence µm = 0.8 hr-1 Ks = 80 mg/l Total volume (V) = 10 lit Flow rate (F)= 50 ml/ min S0 = 50g/ lit Yield Y = 0.3 g-DCW/ g-substrate To find: biomass X and limiting substrate concentration Monod equation S = Ks D/ µm -D D= F/V F= 50 ml/ min = 3000ml/ hr D= F/V = 3000/10000 = 0.3 S= 80*0.3/0.8-0.3 = 48 mg/l X = y [So - S] X = 0.3 *[50-0.048] = 0.3 [49.952] = 14.985 = 15 g/l 9. The respiratory coefficient for the reaction aCHmOn + b O2 + cNH3 a) f/a b) e/b 10. A. B. C. D. a) b)

match the following Pressure Foam Turbidity Flow rate A-3 B-4 C-1 D-2 A-4 B-1 C-2 D-3

d CHαOβNγ + eH2O+ fCO2 is defined as c) b/f d) f/b

1. photometer 2. rotameter 3. diaphragm gauge 4. rubber sheathed electrode c) A-1 B-3 C-2 D-4 d) A-1 B-2 C-3 D-4

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