Fluid Flow Questions and Answers

Multiple Choice Questions (MCQ) and Answers on Fluid Flow

Question.1: Pluronic F68 protects mammalian cells from damage stems as it is a/an

  1. surface active agent which stabilizes foams
  2. surface active agent which destabilizes foams
  3. excellent source of vitamins
  4. coagulant

Answer: 1

Question.2: Reynolds number for turbulent flow over a plate should be more than

  1. 5 x 10-5
  2. 106
  3. 5 x 105
  4. 500

Answer: 2

Question.3: Reynolds number for laminar flow over a plate should be less than

  1. 500 mm
  2. 5 x 10-5
  3. 5 x 105
  4. 5 m

Answer: 3

Question.4: The approach which is commonly used to determine the level of damage to animal cells in a culture medium is to monitor

  1. the concentration of lactate in the medium
  2. the level of lactate oxidase activity in the medium
  3. the level of lactate dehydrogenase activity
  4. the level of lactase activity in the medium

Answer: 3

Question.5: A Brookfield viscometer cannot determine the shear stress because

  1. the shear stress is not defined
  2. a computer is required
  3. the impeller type is given only by numbers
  4. all of the above

Answer: 1

Question.6: Which of the following is correct?

  1. The viscosity of liquids and gases decrease with increasing temperature
  2. The viscosity of liquids and gases increase with increasing temperature
  3. the viscosity of gases increases with increasing temperature, but decreases in liquids
  4. the viscosity of gases decreases with increasing temperature, but decreases in liquids.

Answer: 3

Question.7: The Komologorov eddy size

  1. is constant at all stirrer speeds
  2. increases with stirrer speed
  3. decreases with stirrer speed
  4. becomes zero when the stirrer speed is very low

Answer: 3

Question.8: A stirred tank reactor containing a fluid with a density of 2.5 g.ml-1 and viscosity of 0.002 kg m-1s-1 is mixed at 120 rpm. If the fluid is mixed with an impeller having diameter 50 cm, then the Reynolds number of the liquid in the reactor is

  1. 2500
  2. 100
  3. 12,50,000
  4. 1,000,000

Answer: 3

Question.9: If the viscosity of a fluid decreases with the length of time that it is being mixed, then this fluid is

  1. newtonian
  2. rheopectic
  3. viscoelastic
  4. thixotropic

Answer: 4

Question.10: Which of the following describes the importance of the Kolmogorov eddy size in the biotechnology?

  1. The Kolmogorov eddy size is a measure of the smallest eddy size in a liquid
  2. When the Kolmogorov eddy size become equivalent or smaller than the cell or particle diameter, then the cell or particle will become susceptible to shear damage
  3. At the Kolmogorov eddy size, much of the energy of the originating eddy will be released
  4. All of the above

Answer: 4

Question.11: A thixotropic fluid is one in which the viscosity

  1. is constant regardless of the stirrer speed or mixing time
  2. changes during mixing but returns to its original state after mixing
  3. increases with mixing time
  4. decreases with mixing time

Answer: 4

Question.12: Newtonian fluid is one in which the viscosity

  1. remains constant with time and power input
  2. increases with the level of power input
  3. decreases with the level of power input
  4. drastically increases with the level of power input

Answer: 1

Question.13: A Newtonian fluid is one in which the viscosity

  1. is constant regardless of the stirrer speed or mixing time
  2. changes during mixing but returns to its original state after mixing
  3. increases with increasing stirrer speed
  4. decreases with increasing stirrer speed

Answer: 1

Question.14: Which pattern of mixing is preferred in stirred tank reactors during the culture of aerobic microorganisms?

  1. Laminar flow
  2. Transient flow
  3. turbulent flow
  4. all of these

Answer: 3

Question.15: Animal cell cultures do not have much effect on shear forces because

  1. the cell size is generally smaller than the critical eddy size at which shear will have an effect
  2. cells are larger than the critical eddy size at which shear will have an effect
  3. animal cells have cell walls
  4. animal cells have cell membranes

Answer: 1

Question.16: The viscosity of the culture fluid is classified as both pseudoplastic and thixotropic which indicates that the viscosity

  1. increases with stirring speed but decreases with mixing time
  2. increases with stirring speed and increases with mixing time
  3. decreases with stirring speed but increases with mixing time
  4. decreases with stirring speed and decreases with mixing time

Answer: 4

Question.17: Pluronic F68 is added to cell culture media as

  1. a nutrient
  2. a shear protectorant
  3. to increase oxygen transfer rates
  4. all of these

Answer: 2

Question.18: The viscosity of a fluid increases with increasing stirrer speed. This fluid would be best described as being

  1. newtonian
  2. pseudoplastic
  3. dilatant
  4. thixotropic

Answer: 3

Question.19: A dilatant fluid is one in which the viscosity

  1. is constant regardless of the stirrer speed or mixing time
  2. changes during mixing but returns to its original state after mixing
  3. increases with increasing stirrer speed
  4. decreases with increasing stirrer speed

Answer: 3

Question.20: A rheopectic fluid is one in which the viscosity

  1. is constant regardless of the stirrer speed or mixing time
  2. changes during mixing but returns to its original state after mixing
  3. changes during mixing but returns to its original state after mixing
  4. decreases with mixing time

Answer: 3

Question.21: A fluid in which the viscosity increases with increasing stirrer speed and mixing time can be called as

  1. newtonian fluid
  2. newtonian fluid
  3. dilatant, rheopectic fluid
  4. dilatant pseudoplastic fluid

Answer: 3

Question.22: The medium will have the highest viscosity (considering that the cells do not secrete gums) with the presence of

  1. single celled bacteria
  2. filamentous fungi that form pellets
  3. filamentous fungi that grow as long poorly branched chains
  4. yeast

Answer: 3

Question.23: Water is a

  1. newtonian fluid
  2. pseudoplastic
  3. dilatant
  4. rheopectic

Answer: 1

Question.24: Which of the following affect the Kolmogorov eddy size?

  1. Stirrer speed
  2. Physical properties of the liquid
  3. Size and type of impeller
  4. All of these

Answer: 4

Question.25: A liquid is flowing at 11,400 l.h-1 along a pipeline having a diameter of 4 cm. If the liquid has a density of 1 g.ml-1 and viscosity of 0.001kg.m-1.s-1, then the liquid would be in the

  1. laminar phase
  2. transient phase
  3. turbulent phase
  4. any of the phase

Answer: 3

Question.26: The viscosity of a fluid increases with the length of time that it is being mixed. This fluid would be best described as being

  1. newtonian
  2. rheopectic
  3. viscoelastic
  4. thixotropic

Answer: 2

Question.27: Which of the following can act as a shear protectorant?

  1. Serum
  2. Silicone oil
  3. Glucose
  4. Glutamic acid

Answer: 1

Question.28: The viscous nature of a non-Newtonian fluid

  1. remains constant with time and power input
  2. changes with the level of power input and/or the length of time during which the fluid is mixed
  3. is similar to that of a perfect gas
  4. is similar to that of water

Answer: 2

Question.29: Which of the following compound, if added to a solution will lead to the greatest increase in viscosity?

  1. A globular protein
  2. Glucose
  3. A long chain protein such as albumin
  4. Water

Answer: 3

Question.30: A Brookfield viscometer measures viscosity by determining

  1. the shear stress
  2. the shear rate
  3. the shear stress and shear rate
  4. the torque required to move an impeller at a set speed

Answer: 4

Question.31: Which of the following factors will affect the sensitivity of animal cells to shear conditions?

  1. Cell size
  2. Availability of nutrients in the medium
  3. The presence of shear protectorants in the medium
  4. All of the above

Answer: 4

Question.32: The best described action of Pluronic F68 (non-ionic detergent) in a cell culture medium is that, it

  1. acts on the surface properties of the cells and the culture medium
  2. provides nutrients for the cells
  3. acts as a flocculant
  4. acts as a coagulant

Answer: 1

Question.33: Mixing in stirred tank reactors can

  1. be described as either laminar, transient or turbulent
  2. achieve turbulent conditions by increasing the stirrer speed
  3. induce laminar flow conditions by the addition of baffles
  4. all of the above

Answer: 1

Question.35: In animal cell bioreactor, bubble damage can be minimized by

  1. the addition of a shear protectorant
  2. using a bubble free oxygen delivery system
  3. headspace aeration
  4. all of the above

Answer: 4

Question.36: The viscosity of a fluid changes with either stirrer speed or mixing time. But when mixing ceases, the viscosity returns to its original state. This fluid is best described as

  1. newtonian
  2. rheopectic
  3. viscoelastic
  4. thixotropic

Answer: 3

Question.37: In sparged mammalian cell bioreactors, the cell damage is caused because of

  1. shear stress arising during mixing of the cell culture fluid
  2. shear stresses arising from the breakup of bubbles at the liquid surface
  3. shear stresses between bubbles in foam at the liquid surface
  4. all of the above

Answer: 1

Question.38: he SI unit for viscosity is

  1. kg.m-1.s-1
  2. kg.m-2.s-2
  3. kg.m-3.s-1
  4. kg.m-1.s-2

Answer: 1

Question.39: Bubble free aeration systems requires

  1. silicone tubing or gas permeable membranes to facilitate gas transfer
  2. carbon dioxide instead of air to supply oxygen
  3. silicone tubing or gas permeable membranes to remove carbon dioxide by oxygen in the form of hydrogen peroxide
  4. filled headspace of the reactor with carbon dioxide

Answer: 1

Question.40: Non-linear relationship between shear stress and shear rate exists in

  1. newtonian fluids
  2. non-newtonian fluids
  3. both (a) and (b)
  4. none of these

Answer: 2

Question.41: If the viscosity of a fluid decreases with increasing stirrer speed, then the nature of the fluid is

  1. newtonian
  2. pseudoplastic
  3. dilatant
  4. thixotropic

Answer: 2

Question.42: A pseudoplastic fluid is one in which the viscosity

  1. is constant regardless of the stirrer speed or mixing time
  2. changes during mixing but returns to its original state after mixing
  3. increases with increasing stirrer speed
  4. decreases with increasing stirrer speed

Answer: 4

Question.43: A viscoelastic fluid is one in which the viscosity

  1. is constant regardless of the stirrer speed or mixing time
  2. changes during mixing but returns to its original state after mixing
  3. increases with increasing stirrer speed
  4. decreases with increasing stirrer speed

Answer: 2

Question.44: The viscosity of liquid was classified as both dilatant and rheopectic, which means that the viscosity

  1. increased with stirring speed but decreased with mixing time
  2. increased with stirring speed and increased with mixing time
  3. decreased with stirring speed but increased with mixing time
  4. decreased with stirring speed and decreased with mixing time

Answer: 2

Question.45: Which of the following describes the detrimental effect of bubbles on animal cells?

  1. Cells trapped on the surface of bubbles can be damaged when the bubbles explode, releasing their pressure and surface energies
  2. Cells trapped in the moving foam can be dragged apart by the bubbles
  3. Both (a) and (b)
  4. Bubbles can explode in the liquid medium causing the release of ultraviolet radiation

Answer: 3

Question.46: A fluid in which the viscosity decreases with increasing stirrer speed and mixing time, can be represented as

  1. newtonian fluid
  2. pseudoplastic, thixotropic fluid
  3. dilatant, rheopectic fluid
  4. dilatant, pseudoplastic fluid

Answer: 2

Question.47: Filamentous fungal cells are more shear sensitive than bacterial cells because of

  1. the presence of citin in cell walls of filamentous fungi
  2. larger in size than bacterial cells and therefore are more susceptible to shear forces
  3. fungal cells are much larger than bacterial cells
  4. all of the above

Answer: 4

Question.48: The viscosity of water at STP is approximately

  1. 0.005 kg.m-1.s-1
  2. 0.001 kg.m-1.s-1
  3. 0.003 kg.m-2.s-1
  4. 0.1 g.cm-1.s-1

Answer: 2