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 10^36.2 s^-1

#Question id: 403

#Section 2: General Biology

For the reaction A -> B, DG'° = –60 kJ/mol.  The reaction is started with 10 mmol of A; no B is initially present.  After 24 hours, analysis reveals the presence of 2 mmol of B, 8 mmol of A. Which is the most likely explanation?

#Question id: 403

#Section 4: Fundamentals of Biological Engineering

For the reaction A -> B, DG'° = –60 kJ/mol.  The reaction is started with 10 mmol of A; no B is initially present.  After 24 hours, analysis reveals the presence of 2 mmol of B, 8 mmol of A. Which is the most likely explanation?

#Question id: 404

#Section 4: Fundamentals of Biological Engineering

When a mixture of 3-phosphoglycerate and 2-phosphoglycerate is incubated at 25 °C with phosphoglycerate mutase until equilibrium is reached, the final mixture contains six times as much 2-phosphoglycerate as 3-phosphoglycerate.  Which one of the following statements is most nearly correct, when applied to the reaction as written?  (R = 8.315 J/mol·K; T = 298 K)  3-Phosphoglycerate -> 2-phosphoglycerate

#Question id: 405

#Section 4: Fundamentals of Biological Engineering

When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase (which catalyzes the interconversion of these two compounds) until equilibrium is reached, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate.  Which one of the following statements is best applied to this reaction outlined below? (R = 8.315 J/mol·K; T = 298 K) Glucose 6-phosphate -> fructose 6-phosphate

#Question id: 406

#Section 2: General Biology

Hydrolysis of 1 M glucose 6-phosphate catalyzed by glucose 6-phosphatase is 99% complete at equilibrium (i.e., only 1% of the substrate remains). Which of the following statements is most nearly correct? (R = 8.315 J/mol·K; T = 298 K)

#Question id: 406

#Section 4: Fundamentals of Biological Engineering

Hydrolysis of 1 M glucose 6-phosphate catalyzed by glucose 6-phosphatase is 99% complete at equilibrium (i.e., only 1% of the substrate remains). Which of the following statements is most nearly correct? (R = 8.315 J/mol·K; T = 298 K)