GATE HELPLINE Bioprocess Engineering MCQ II

GATE HELPLINE BIOPROCESS ENGINEERING MCQs-II

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A bioreactor of working volume 50 m3 produces a metabolite (X) in batch culture under given operation conditions form a substrate (S). The final concentration of metabolite at the end of each run was 1.1kg m-3. The bioreactor was operated to complete 70 runs in each year. 11. What will be the annual output of the system (production of metabolite (X)) in Kg per year? a) 55 c) 45.5 b) 3850 d) 77 Solution: Volume = 50 m3 Total output = no of runs * product = 70 * 1.1 = 77 12. What will be the overall productivity of the system in Kg year-1 m-3? a) 19250 c) 3850 b) 38.50 d) 77 Solution: Overall productivity for 1 run by reactor = 11 * 5 = 55 kg Total productivity for 70 runs = 55 kg * 70 runs = 3850 kg/ year/ m3 13. Aeration in a bioreactor is provided by a) Impeller c) sparger b) Baffles d) all the above 14. In a bioreactor baffles are incorporated to a) Prevent vortex and to improve aeration efficiency b) Minimize the size of air bubble for greater aeration c) Minimize the size of air bubble for greater aeration d) Maintain uniform nutrient medium 15. An enzyme following michelis menten kinetics with Vm= 2.5 mmol m-3s-1 and Km= 5.0mM was used to carry out the reaction in a batch stirred reactor. Starting with an initial substrate concentration of 0.1M, the time required for 50% conversion of the substrate will be about (ln2=0.69) a) 01 hr c) 02 hr b) 06 hr d) 12hr 16. During the media preparation for cultivation of cells, insoluble precipitates of calcium phosphates are often formed. Identify which method can be adopted to avoid this problem a) Hold the pH at 5.6 b) Hold the pH at 7.5 c) Add calcium salt first and then phosphate source d) None of the above

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17. An immobilized enzyme being used in a continuous plug flow reactor exhibits an effectiveness factor (η) of 1.2. The value of η being greater than one could be apparently due to one of the following reasons. Identify the correct reason. a) The enzyme follows substrate inhibited kinetics with internal pore diffusion limitation. b) The enzyme experiences external film diffusion limitation c) The enzyme follows sigmoidal kinetics d) The immobilized enzyme is operationally unstable 18. The kinetics of the disintegration of baker’s yeast in a bead mill is described as dP/dt = K(Pm-P). Where P is the concentration of protein released and Pm is the maximum protein concentration achievable. K is the first order rate constant and is 0.5 hr-1 for the system studied. The time required for the release of 90% of the intracellular proteins will be: a) 10 hr c) 4.6 hr b) 02 hr d) none of the above Solution: normal integration of the equation given above 19. Inversion of sucrose by immobilized invertase follows substrate inhibited kinetics. The reaction rate (v) in mol m-3 hr-1 can be expressed as V= 800[S] + 50[S]+[S]2 . Where [S] is the sucrose concentration. The immobilized invertase preparation is used in a CSTR with 100 mol m-3 sucrose concentration in the feed stream. If the reaction velocity passes through a maxima at [S] = 20 mol m-3. The feed flow rate for a reactor volume of 1m3 to get the maximum productivity from the reactor should be: a) 0.11 m3 hr-1 c)5.05 m3 hr-1 b) 1.10 m3 hr-1 d) none of the above. 20. Phytase an enzyme produced by aspergillus niger can be absorbed on microcrystalline cellulose powder (MCCP). The adsorption follows a langmuir isotherm and the maximum concentration of the protein that can be obtained on the absorbent is 70 mg cm-1. At a concentration of 50 mg l-1 of protein in the solution. The concentration of protein on the adsorbent reaches 35 mg cm-1. It is desired to recover 90% of the protein from 1.5 litre of the cell free culture filtrate containing 220 mg l-2 protein by addition of MCCP to the solution. The concentration of the protein adsorbed on the solid at equilibrium will be: a) 21.4 mg cm-1 c) 2.14 mg cm-1 b) 214 mg cm-1 d) none of the above

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