Agricultural/Bioengineering Bioprocess Engineering

Question 1

In a batch bioreactor, which growth phase is characterized by microorganisms dividing at their maximum specific growth rate?

Accepted Answer

Log (exponential) phase

Answer

During the log phase, nutrients are abundant and microorganisms divide exponentially at their maximum specific growth rate (μmax).

Question 2

In the Michaelis-Menten enzyme kinetics equation, what does the Michaelis constant (Km) represent?

Accepted Answer

Substrate concentration at half-maximum velocity

Answer

Km is the substrate concentration at which the reaction proceeds at half of Vmax, reflecting the affinity between enzyme and substrate.

Question 3

Which bioreactor type is most widely used in industrial fermentation due to its uniform mixing achieved via mechanical agitation?

Accepted Answer

Stirred tank reactor (STR)

Answer

The stirred tank reactor uses an impeller for mechanical agitation, providing uniform mixing of nutrients, cells, and oxygen throughout the vessel.

Question 4

In the oxygen transfer rate equation OTR = kLa(C* − CL), what does the term kLa represent?

Accepted Answer

Volumetric mass transfer coefficient

Answer

kLa is the volumetric mass transfer coefficient, combining the liquid-film coefficient (kL) with the gas-liquid interfacial area per unit volume (a).

Question 5

Which chromatography technique separates proteins based on their net surface charge at a given pH?

Accepted Answer

Ion exchange chromatography

Answer

Ion exchange chromatography retains charged proteins on oppositely charged resin, then elutes them by increasing ionic strength or changing pH.

Agricultural/Bioengineering Practice Test