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  • Question
  • The viscosity of the culture fluid is classified as both pseudoplastic and thixotropic which indicates that the viscosity


  • Options
  • A. increases with stirring speed but decreases with mixing time
  • B. increases with stirring speed and increases with mixing time
  • C. decreases with stirring speed but increases with mixing time
  • D. decreases with stirring speed and decreases with mixing time

  • Correct Answer
  • decreases with stirring speed and decreases with mixing time 


  • Fluid Flow problems


    Search Results


    • 1. Reynolds number for turbulent flow over a plate should be more than

    • Options
    • A. 5 x 10-5
    • B. 106
    • C. 5 x 105
    • D. 500
    • Discuss
    • 2. Animal cell cultures do not have much effect on shear forces because

    • Options
    • A. the cell size is generally smaller than the critical eddy size at which shear will have an effect
    • B. cells are larger than the critical eddy size at which shear will have an effect
    • C. animal cells have cell walls
    • D. animal cells have cell membranes
    • Discuss
    • 3. The Komologorov eddy size

    • Options
    • A. is constant at all stirrer speeds
    • B. increases with stirrer speed
    • C. decreases with stirrer speed
    • D. becomes zero when the stirrer speed is very low
    • Discuss
    • 4. Which pattern of mixing is preferred in stirred tank reactors during the culture of aerobic microorganisms?

    • Options
    • A. Laminar flow
    • B. Transient flow
    • C. turbulent flow
    • D. all of these
    • Discuss
    • 5. Non-linear relationship between shear stress and shear rate exists in

    • Options
    • A. newtonian fluids
    • B. non-newtonian fluids
    • C. both (a) and (b)
    • D. none of these
    • Discuss
    • 6. The viscosity of a fluid increases with increasing stirrer speed. This fluid would be best described as being

    • Options
    • A. newtonian
    • B. pseudoplastic
    • C. dilatant
    • D. thixotropic
    • Discuss
    • 7. Filamentous fungal cells are more shear sensitive than bacterial cells because of

    • Options
    • A. the presence of citin in cell walls of filamentous fungi
    • B. larger in size than bacterial cells and therefore are more susceptible to shear forces
    • C. fungal cells are much larger than bacterial cells
    • D. all of the above
    • Discuss
    • 8. The viscosity of water at STP is approximately

    • Options
    • A. 0.005 kg.m-1.s-1
    • B. 0.001 kg.m-1.s-1
    • C. 0.003 kg.m-2.s-1
    • D. 0.1 g.cm-1.s-1
    • Discuss
    • 9. A thixotropic fluid is one in which the viscosity

    • Options
    • A. is constant regardless of the stirrer speed or mixing time
    • B. changes during mixing but returns to its original state after mixing
    • C. increases with mixing time
    • D. decreases with mixing time
    • Discuss
    • 10. Which of the following factors will affect the sensitivity of animal cells to shear conditions?

    • Options
    • A. Cell size
    • B. Availability of nutrients in the medium
    • C. The presence of shear protectorants in the medium
    • D. All of the above
    • Discuss


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