⚗️ Biochemical Engineering Solved MCQs with Answers

Practice 513 approved ⚗️ Biochemical Engineering questions with verified answers from the 🧬 Medical Science subject for Pakistan exams.

513 solved MCQs

Which of the following is not classified as an axial flow impeller?Answer: A Rushton turbine Power number (Nₚ) is also known asAnswer: Newton's number Flooding is a condition/phenomenon which occur in a bioreactor whenAnswer: The air escapes without being distributed by the agitator A cylindrical reactor has a liquid volume of 100,000 litres. It has an aspect ratio the ratio of the channel height to width of 1:1. The height of the liquid in the reactor will be approximately:Answer: 5.0 m Detergent like substances produced by microorganisms during a fermentation will lead toAnswer: All of these A cylindrical reactor fitted with Rushton Turbine has a liquid volume of 100,000 litres. It has an aspect ratio (the ratio of the channel height to the width) of 2:1. The diameter of the impeller should be approximately:Answer: 1.3 m In the bubble boundary layer, oxygen concentration can be determined by measuringAnswer: The steady state oxygen concentration in a mixed aerated reactor before inoculation Impeller damage can be minimized byAnswer: Using specially designed axial flow impellers To increase the oxygen transfer rate in a shake flask culture system, which of the following (s) is/are followed?Answer: All of these What is/are the major difference(s) between disc and turbine type stirrer?Answer: Both (a) and (b) In the design of a paddle agitator, the ratio of paddle diameter to tank diameter is normally taken asAnswer: 0.8 The oxygen absorption rate can be determined byAnswer: All of these Industrial paddle agitators turn at the speed ofAnswer: 20 and 150 rpm The dynamic technique is based on theAnswer: Oxygen material balance in an aerated batch fermenter during the growth of microorganisms The addition of antifoams to an aerated bioreactor will decrease oxygen transfer rates because antifoamsAnswer: All of these During fermentation, the saturation concentration of oxygen was reduced from 7 ppm. to 1 ppm. Which one of the following conclusions can be drawn?Answer: No conclusion can be drawn If the stirrer speed is too slow, bubbles will accumulate and coalescese under the impeller. This phenomenon is known as aAnswer: Flooded impeller 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?Answer: No conclusion on the growth rate can be withdrawn Reynolds (Reᵢ) number for the impeller is given by (where Dᵢ, stirrer diameter; N, stirrer speed, ρ, density of fluid and μ, viscosity of fluid)Answer: Dᵢ²Nρ/μ The advantage of axial flow impellers over radial flow impellers is that axial flow impellersAnswer: Provide better lift of solids Larger propellers turn at the speed ofAnswer: 400 to 800 rpm A microbial population in a suspension culture will only be limited by oxygen availability if the dissolved oxygenAnswer: Concentration is less than the critical concentration Froude number is avoided in calculation of power requirements for low viscosity liquid mixing systems whenAnswer: Both (a) and (b) A fermentation system has a Kₗaof 3 s⁻¹ and a C₀* of 5 ppm of O₂. If the bulk liquid is completely depleted of oxygen, then the oxygen transfer rate will be equal toAnswer: 15 mg.l⁻¹.s⁻¹ During aeration, a cylindrical reactor had a height of 10 m. Without aeration, the height was 7.5 m. Under these aeration and mixing conditions, the gas hold up in the reactor isAnswer: 25% A fermentation system has aKₗa of 3 s⁻¹ and a C₀* of 5 ppm of O₂. If the bulk liquid is saturated with oxygen then the oxygen transfer rate will be equal toAnswer: zero Which of the following would be best described as a radial flow impeller?Answer: A Rushton turbine Small propellers turn at the speed of eitherAnswer: 1150 rpm or 1750 rpm In aerobic microorganisms cultures radial flow impellers are used becauseAnswer: They provide high shear mixing conditions The effect of increasing the stirrer speed in an unbaffled stirred tank reactor is thatAnswer: As the stirrer speed increases, the liquid will continue to circulate. Eventually a vortex will form.