200 Best MCQs on Agitation and aeration- biochemical engineering
Q57). The dynamic technique is based on the
a).oxygen material balance in an aerated batch fermenter during the growth of microorganisms
b).change of the oxygen concentration
c).oxidation of the sodium sulfite to sodium sulfate
d).oxygen material balance in a fermenter
Correct Answer:
oxygen material balance in an aerated batch fermenter during the growth of microorganisms
Explaination:
Q58). The addition of antifoams to an aerated bioreactor will decrease oxygen transfer rates because antifoams
a).increase the tendency of bubbles to coalesce
b).tend to accumulate in the gas liquid interface
c).reduce the surface tension of the liquid
d).All of the above answers
Correct Answer:
All of the above answers
Explaination:
Q59). During fermentation, the saturation concentration of oxygen was reduced from 7 ppm. to 1 ppm. Which one of the following conclusions can be drawn?
a).Microbial growth is oxygen limited since the oxygen concentration is lesser than the saturation concentration
b).Microbial growth is not oxygen limited since the oxygen concentration is lesser than the saturation concentration
c).Experimental error leads to the reduction
d).No conclusion can be drawn
Correct Answer:
No conclusion can be drawn
Explaination:
Q60). If the stirrer speed is too slow, bubbles will accumulate and coalescese under the impeller. This phenomenon is known as a
a).coalesced impeller
b).flooded impeller
c).river impeller
d).dry impeller
Correct Answer:
flooded impeller
Explaination:
Q61). The maximum solubility of the alkane in the medium is 5 ppm. If the actual dissolved concentration of the alkane in the medium is 1 ppm. what conclusion may be drawn?
a).The growth rate is limited by the rate of mass transfer of the alkane into the fermentation medium
b).The growth rate is limited by the intrinsic kinetic properties of the cells and not by mass transfer
c).The growth rate is neither mass transfer nor kinetically limited
d).No conclusion on the growth rate can be withdrawn
Correct Answer:
No conclusion on the growth rate can be withdrawn
Explaination:
Q62). The advantage of axial flow impellers over radial flow impellers is that axial flow impellers
a).provide better lift of solids
b).provide high shear conditions
c).provide low shear conditions
d).are cheaper to build
Correct Answer:
provide better lift of solids
Explaination:
Q63). Larger propellers turn at the speed of
a).20 to 150 rpm
b).150 to 300 rpm
c).400 to 800 rpm
d).1150 rpm
Correct Answer:
400 to 800 rpm
Explaination:
Q64). A microbial population in a suspension culture will only be limited by oxygen availability if the dissolved oxygen
a).concentration is less than the critical concentration
b).concentration is greater than the critical concentration
c).levels are greater than the saturation concentration of oxygen
d).levels are equal to saturation oxygen level
Correct Answer:
concentration is less than the critical concentration
Explaination: