Practice Questions

  1. Home
  2. Free Resources
  3. Practice Questions
  4. 10768
TLS Online TPP Program

#Question id: 123

Which would you expect for the fatty acyl chains of the membrane phospholipids of bacteria grown at low temperature?

#Section 2: General Biology

  1. Proportion of unsaturated fatty acyl groups increases.

  2. Proportion of unsaturated fatty acyl groups decreases.

  3. No change in the proportion of saturated versus unsaturated acyl groups.

  4. More cholesterol is produced and is inserted between the fatty acyl chains of the membrane.

More Questions
TLS Online TPP Program

#Question id: 14246

#Section 5: Bioprocess Engineering and Process Biotechnology

A steam steriliser is used to sterilise liquid medium for fermentation. The initial concentration of contaminating organisms is 108 per litre. For design purposes, the final acceptable level of contamination is usually taken to be 10-3cells; this corresponds to a risk that one batch in a thousand will remain contaminated even after the sterilisation process is complete. For how long should 1 m3 medium be treated if the temperature is 80⁰C ________________.10^6

 To be safe, assume that the contaminants present are spores of Bacillus stearothermophilus, one of the most heat-resistant microorganisms known. For these spores the activation energy for thermal death is 283 kJ gmo1-1 and the Arrhenius constant is 1036.2 s-1
TLS Online TPP Program

#Question id: 14247

#Section 5: Bioprocess Engineering and Process Biotechnology

A steam steriliser is used to sterilise liquid medium for fermentation. The initial concentration of contaminating organisms is 108 per litre. For design purposes, the final acceptable level of contamination is usually taken to be 10-3cells; this corresponds to a risk that one batch in a thousand will remain contaminated even after the sterilisation process is complete. For how long should 1 m3 medium be treated if the temperature is 121⁰C ________________.

 To be safe, assume that the contaminants present are spores of Bacillus stearothermophilus, one of the most heat-resistant microorganisms known. For these spores the activation energy for thermal death is 283 kJ gmo1-1 and the Arrhenius constant is 1036.2 s-1

TLS Online TPP Program

#Question id: 14248

#Section 5: Bioprocess Engineering and Process Biotechnology

A steam steriliser is used to sterilise liquid medium for fermentation. The initial concentration of contaminating organisms is 108 per litre. For design purposes, the final acceptable level of contamination is usually taken to be 10-3cells; this corresponds to a risk that one batch in a thousand will remain contaminated even after the sterilisation process is complete. For how long should 1 m3 medium be treated if the temperature is 140⁰C ________________.

        To be safe, assume that the contaminants present are spores of Bacillus stearothermophilus, one of the most heat-resistant microorganisms known. For these spores the activation energy for thermal death is 283 kJ gmo1-1 and the Arrhenius constant is 1036.2 s-1

TLS Online TPP Program

#Question id: 14249

#Section 5: Bioprocess Engineering and Process Biotechnology

Aspartase enzyme is used industrially for manufacture of aspartic acid, a component of low-calorie sweetener. Fumaric acid and ammonia are converted to aspartic acid according to the equation:

 
                                        
Under investigation is a process using aspartase in intact Bacillus cadaveris cells. In the substrate range of interest, the conversion can be described using Michaelis-Menten kinetics with K m 4.0 gl-1. The substrate solution contains 15% (w/v) ammonium fumarate; enzyme is added in the form of lyophilised cells and the reaction stopped when 85% of the substrate is converted. At 32⁰C vmax for the enzyme is 5.9 g l-1h-1 and its half-life is 10.5 d. At 37⁰C Vmax increases to 8.5 g l- 1 h- I but the half-life is reduced to 2.3 d. The average downtime between batch reactions is 28 h. calculate the reactor volume required to produce 5000 tonnes of aspartic acid per year
TLS Online TPP Program

#Question id: 14250

#Section 5: Bioprocess Engineering and Process Biotechnology

A stirred-tank reactor is to be scaled down from 10 m3 to 0.1 m3. The dimensions of the large tank are: Dt = 2 m; Di = 0.5 m; N = 100 rpm. What would be the required rotational speed of the impeller in the small tank if impeller Re number is constant?
______________________
TLS Online TPP Program

#Question id: 14251

#Section 5: Bioprocess Engineering and Process Biotechnology

Yeast cells are recovered from a fermentation broth by using a tubular centrifuge. Sixty percent (60%) of the cells are recovered at a flow rate of 12 l/min with a rotational speed of 4000 rpm. Recovery is inversely proportional to flow rate. a. To increase the recovery of cells to 95% at the same flow rate, what should be the rpm of the centrifuge?
____________________