Fluid Flow

Q1: Which of the following compound, if added to a solution will lead to the greatest increase in viscosity?

A A globular protein

B Glucose

C A long chain protein such as albumin

D Water

ANS:C - A long chain protein such as albumin

No answer description is available.

Q2: Which of the following factors will affect the sensitivity of animal cells to shear conditions?

A Cell size

B Availability of nutrients in the medium

C The presence of shear protectorants in the medium

D All of the above

ANS:D - All of the above

No answer description is available.

Q3: The approach which is commonly used to determine the level of damage to animal cells in a culture medium is to monitor

A the concentration of lactate in the medium

B the level of lactate oxidase activity in the medium

C the level of lactate dehydrogenase activity

D the level of lactase activity in the medium

ANS:C - the level of lactate dehydrogenase activity

No answer description is available.

Q4: Mixing in stirred tank reactors can

A be described as either laminar, transient or turbulent

B achieve turbulent conditions by increasing the stirrer speed

C induce laminar flow conditions by the addition of baffles

D all of the above

ANS:A - be described as either laminar, transient or turbulent

How can it be possible that flow can be laminar in a stirrer tank?

Q5: Pluronic F68 is added to cell culture media as

A a nutrient

B a shear protectorant

C to increase oxygen transfer rates

D all of these

ANS:B - a shear protectorant

No answer description is available.

Q6: Which of the following describes the detrimental effect of bubbles on animal cells?

A Cells trapped on the surface of bubbles can be damaged when the bubbles explode, releasing their pressure and surface energies

B Cells trapped in the moving foam can be dragged apart by the bubbles

C Both (a) and (b)

D Bubbles can explode in the liquid medium causing the release of ultraviolet radiation

ANS:C - Both (a) and (b)

No answer description is available.

Q7: The SI unit for viscosity is

A kg.m-1.s-1

B kg.m-2.s-2

C kg.m-3.s-1

D kg.m-1.s-2

ANS:A - kg.m-1.s-1

No answer description is available.

Q8: A Brookfield viscometer measures viscosity by determining

A the shear stress

B the shear rate

C the shear stress and shear rate

D the torque required to move an impeller at a set speed

ANS:D - the torque required to move an impeller at a set speed

No answer description is available.

Q9: Which of the following describes the importance of the Kolmogorov eddy size in the biotechnology?

A The Kolmogorov eddy size is a measure of the smallest eddy size in a liquid

B 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

C At the Kolmogorov eddy size, much of the energy of the originating eddy will be released

D All of the above

ANS:D - All of the above

No answer description is available.

Q10: The viscosity of liquid was classified as both dilatant and rheopectic, which means that the viscosity

A increased with stirring speed but decreased with mixing time

B increased with stirring speed and increased with mixing time

C decreased with stirring speed but increased with mixing time

D decreased with stirring speed and decreased with mixing time

ANS:B - increased with stirring speed and increased with mixing time

No answer description is available.

Q11: Reynolds number for turbulent flow over a plate should be more than

A 5 x 10-5

B 106

C 5 x 105

D 500

ANS:B - 106

No answer description is available.

Q12: A rheopectic fluid is one in which the viscosity

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

ANS:C - increases with mixing time

No answer description is available.

Q13: A viscoelastic fluid is one in which the viscosity

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 increasing stirrer speed

D decreases with increasing stirrer speed

ANS:B - changes during mixing but returns to its original state after mixing

No answer description is available.

Q14: 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

A laminar phase

B transient phase

C turbulent phase

D any of the phase

ANS:C - turbulent phase

No answer description is available.

Q15: A fluid in which the viscosity increases with increasing stirrer speed and mixing time can be called as

A newtonian fluid

B pseudoplastic, thixotropic fluid

C dilatant, rheopectic fluid

D dilatant pseudoplastic fluid

ANS:C - dilatant, rheopectic fluid

No answer description is available.

Q16: Newtonian fluid is one in which the viscosity

A remains constant with time and power input

B increases with the level of power input

C decreases with the level of power input

D drastically increases with the level of power input

ANS:A - remains constant with time and power input

No answer description is available.

Q17: A fluid in which the viscosity decreases with increasing stirrer speed and mixing time, can be represented as

A newtonian fluid

B pseudoplastic, thixotropic fluid

C dilatant, rheopectic fluid

D dilatant, pseudoplastic fluid

ANS:B - pseudoplastic, thixotropic fluid

The fluid shows decreasing in viscosity when increase in shear stress.

Because it is a shear thinning process.

For example : paints and oils.

Q18: A viscoelastic fluid is one in which the viscosity

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 increasing stirrer speed

D decreases with increasing stirrer speed

ANS:B - changes during mixing but returns to its original state after mixing

No answer description is available.

Q19: Animal cell cultures do not have much effect on shear forces because

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

ANS:A - the cell size is generally smaller than the critical eddy size at which shear will have an effect

No answer description is available.

Q20: Non-linear relationship between shear stress and shear rate exists in

A newtonian fluids

B non-newtonian fluids

C both (a) and (b)

D none of these

ANS:B - non-newtonian fluids

No answer description is available.

Q21: In animal cell bioreactor, bubble damage can be minimized by

A the addition of a shear protectorant

B using a bubble free oxygen delivery system

C headspace aeration

D all of the above

ANS:D - all of the above

But that point they are very close to each other so the stress is developing directly and also a reason of strain so we can consider stress and strain equally and simultaneously.

Q22: If the viscosity of a fluid decreases with increasing stirrer speed, then the nature of the fluid is

A newtonian

B pseudoplastic

C dilatant

D thixotropic

ANS:B - pseudoplastic

What I am saying is fluid shows decreasing in viscosity with increasing in shear stress.

Q23: A dilatant fluid is one in which the viscosity

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 increasing stirrer speed

D decreases with increasing stirrer speed

ANS:C - increases with increasing stirrer speed

No answer description is available.

Q24: Which of the following affect the Kolmogorov eddy size?

A Stirrer speed

B Physical properties of the liquid

C Size and type of impeller

D All of these

ANS:D - All of these

No answer description is available.

Q25: If the viscosity of a fluid decreases with the length of time that it is being mixed, then this fluid is

A newtonian

B rheopectic

C viscoelastic

D thixotropic

ANS:D - thixotropic

No answer description is available.

Q26: The best described action of Pluronic F68 (non-ionic detergent) in a cell culture medium is that, it

A acts on the surface properties of the cells and the culture medium

B provides nutrients for the cells

C acts as a flocculant

D acts as a coagulant

ANS:A - acts on the surface properties of the cells and the culture medium

No answer description is available.

Q27: 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

A 2500

B 100

C 12,50,000

D 1,000,000

ANS:C - 12,50,000

No answer description is available.

Q28: Which pattern of mixing is preferred in stirred tank reactors during the culture of aerobic microorganisms?

A Laminar flow

B Transient flow

C turbulent flow

D all of these

ANS:C - turbulent flow

No answer description is available.

Q29: Which of the following can act as a shear protectorant?

A Serum

B Silicone oil

C Glucose

D Glutamic acid

ANS:A - Serum

No answer description is available.

Q30: The Komologorov eddy size

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

ANS:C - decreases with stirrer speed

No answer description is available.

Q31: The viscosity of the culture fluid is classified as both pseudoplastic and thixotropic which indicates that the viscosity

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

ANS:D - decreases with stirring speed and decreases with mixing time

No answer description is available.

Q32: Filamentous fungal cells are more shear sensitive than bacterial cells because of

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

ANS:D - all of the above

No answer description is available.

Q33: Which of the following is correct?

A The viscosity of liquids and gases decrease with increasing temperature

B The viscosity of liquids and gases increase with increasing temperature

C the viscosity of gases increases with increasing temperature, but decreases in liquids

D the viscosity of gases decreases with increasing temperature, but decreases in liquids.

ANS:C - the viscosity of gases increases with increasing temperature, but decreases in liquids

No answer description is available.

Q34: A Brookfield viscometer cannot determine the shear stress because

A the shear stress is not defined

B a computer is required

C the impeller type is given only by numbers

D all of the above

ANS:A - the shear stress is not defined

No answer description is available.

Q35: The viscosity of water at STP is approximately

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

ANS:B - 0.001 kg.m-1.s-1

No answer description is available.

Q36: The medium will have the highest viscosity (considering that the cells do not secrete gums) with the presence of

A single celled bacteria

B filamentous fungi that form pellets

C filamentous fungi that grow as long poorly branched chains

D yeast

ANS:C - filamentous fungi that grow as long poorly branched chains

No answer description is available.

Q37: Reynolds number for laminar flow over a plate should be less than

A 500 mm

B 5 x 10-5

C 5 x 105

D 5 m

ANS:C - 5 x 105

No answer description is available.

Q38: A Newtonian fluid is one in which the viscosity

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 increasing stirrer speed

D decreases with increasing stirrer speed

ANS:A - is constant regardless of the stirrer speed or mixing time

No answer description is available.

Q39: A thixotropic fluid is one in which the viscosity

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

ANS:D - decreases with mixing time

No answer description is available.

Q40: The viscous nature of a non-Newtonian fluid

A remains constant with time and power input

B changes with the level of power input and/or the length of time during which the fluid is mixed

C is similar to that of a perfect gas

D is similar to that of water

ANS:B - changes with the level of power input and/or the length of time during which the fluid is mixed

No answer description is available.

Q41: The viscosity of a fluid increases with increasing stirrer speed. This fluid would be best described as being

A newtonian

B pseudoplastic

C dilatant

D thixotropic

ANS:C - dilatant

No answer description is available.

Q42: 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

A newtonian

B rheopectic

C viscoelastic

D thixotropic

ANS:C - viscoelastic

No answer description is available.

Q43: The viscosity of a fluid increases with the length of time that it is being mixed. This fluid would be best described as being

A newtonian

B rheopectic

C viscoelastic

D thixotropic

ANS:B - rheopectic

No answer description is available.

Q44: Water is a

A newtonian fluid

B pseudoplastic

C dilatant

D rheopectic

ANS:A - newtonian fluid

No answer description is available.

Q45: Bubble free aeration systems requires

A silicone tubing or gas permeable membranes to facilitate gas transfer

B carbon dioxide instead of air to supply oxygen

C silicone tubing or gas permeable membranes to remove carbon dioxide by oxygen in the form of hydrogen peroxide

D filled headspace of the reactor with carbon dioxide

ANS:A - silicone tubing or gas permeable membranes to facilitate gas transfer

No answer description is available.

Q46: A pseudoplastic fluid is one in which the viscosity

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 increasing stirrer speed

D decreases with increasing stirrer speed

ANS:D - decreases with increasing stirrer speed

No answer description is available.

Q47: Pluronic F68 protects mammalian cells from damage stems as it is a/an

A surface active agent which stabilizes foams

B surface active agent which destabilizes foams

C excellent source of vitamins

D coagulant

ANS:A - surface active agent which stabilizes foams

No answer description is available.

Q48: In sparged mammalian cell bioreactors, the cell damage is caused because of

A shear stress arising during mixing of the cell culture fluid

B shear stresses arising from the breakup of bubbles at the liquid surface

C shear stresses between bubbles in foam at the liquid surface

D all of the above

ANS:A - shear stress arising during mixing of the cell culture fluid

No answer description is available.



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