This set of Bioseparation Processes Multiple Choice Questions & Answers (MCQs) focuses on “Extraction”.
1. Which process of bioseparation involves the use of partitioning of a solute between two immiscible phases?
a) Extraction
b) Filtration
c) Sedimentation
d) Centrifugation
View Answer
Explanation: The extraction is a process which uses the partitioning of a solute between two partially or totally immiscible phases. The extraction can take place in liquid and separates solute from a solid material such phenomenon is known as liquid-liquid extraction and solid-liquid extraction.
2. Which is the most common example of extraction?
a) Antibodies purification
b) Antigen purification
c) Antibiotic purification
d) Salt purification
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Explanation: The process of purification of antibiotic penicillin is the most common example of extraction. Penicillin is stable in organic solvent methyl isobutyl ketone in comparison to aqueous fermentation broth at pH less than 7.
3. How will you design the extraction process?
a) Miscibility of two liquid phases
b) Rate of equilibration of the biomolecules
c) Equilibrium between two phases
d) Both miscibility of two liquid phase and rate of equilibration of molecule between two phases
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Explanation: The process of extraction can be designed depending on the miscibility of two liquid phases in each other and the rate of equilibration of the biomolecules between the two phases. The separation of biolmolecules in liquid-liquid extraction depends on the partitioning of the biomolecules between the liquid phases.
4. What is the characteristic of aqueous two phase extraction?
a) Degrading
b) Nondegrading, nondenaturing
c) Denaturing
d) Degrading, denaturing
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Explanation: The aqueous two phase extraction is a nondegrading as well as nondenaturing technique which can be used for separation of various biomolecules like proteins, cells, viruses, organelles etc. The liquid medium used for separation is molecule friendly and doesn’t harm the properties of the molecules which are being separated using two phase extraction.
5. What is the distribution of a solute at equilibrium between two phases?
a) Partition coefficient
b) Sedimentation coefficient
c) Filtration coefficient
d) Separation coefficient
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Explanation: Distribution or partition coefficient is the distribution of a solute at equilibrium between two liquid phases. For a single stage extraction, one feed stream contacts one extraction solvent system and the solvent mixture are divided into equilibrium extract and raffinate phases.
6. How will you calculate the partition coefficient for the two liquid phases?
a) K = \(\frac{x}{y}\)
b) K = –\(\frac{y}{x}\)
c) K = \(\frac{y}{x}\)
d) K = –\(\frac{x}{y}\)
View Answer
Explanation: The partition coefficient K = \(\frac{y}{x}\) where, y is the concentration of solute in the extract and x is the concentration of raffinate phases. The extraction system having lowest volume have large K value and K near 0 indicates absence of extraction.
7. Calculate the amount of raffinate phase when a solute is distributed at equilibrium with 0.5 partition coefficient and 5 g/ml solute in the extract.
a) 5
b) 10
c) 15
d) 20
View Answer
Explanation: The partition coefficient K = \(\frac{y}{x}\), 0.5 = K = \(\frac{5}{x}\) ∴ x = \(\frac{5}{0.5}\) = 10. The concentration of raffinate phase is 10g/ml.
8. Which model explains the partitioning between phases?
a) K = \(\frac{y}{x}\)
b) K = -exp(\(\frac{M\lambda}{kT}\))
c) K = \(\frac{M}{kT}\)
d) K = exp(\(\frac{M\lambda}{kT}\))
View Answer
Explanation: The model K = exp(\(\frac{M\lambda}{kT}\)) developed by Bronsted is one of the simplest models which describe the partitioning between phases, where M is the molecular weight of the molecule being partitioned, k is the Boltzman constant, T is absolute temperature, λ is the constant used as characteristics of the phase system as well as portioning substance.
9. What is the equation for protein partition coefficient for a solution with two polymers which is very dilute in protein?
a) lnKp = ln \(\frac{y_p}{x_p}\) = a1 p (x1 – y1) + a2 p (x2 – y2) + \(\frac{z_{p F(\phi_x – \phi_y )}}{RT}\)
b) lnKp = ln \(\frac{y_p}{x_p}\) = a1 p (x1 + y1) + a2 p (x2 – y2) + \(\frac{z_{p F(\phi_x – \phi_y )}}{RT}\)
c) lnKp = ln \(\frac{y_p}{x_p}\) = a1 p (x1 – y1) + a2 p (x2 + y2) + \(\frac{z_{p F(\phi_x – \phi_y )}}{RT}\)
d) lnKp = ln \(\frac{y_p}{x_p}\) = a1 p (x1 – y1) – a2 p (x2 – y2) + \(\frac{z_{p F(\phi_x – \phi_y )}}{RT}\)
View Answer
Explanation: The equation for protein partition coefficient for a solution with two polymers which is very dilute in protein is lnKp = ln \(\frac{y_p}{x_p}\) = a1 p (x1 – y1) + a2 p (x2 – y2) + \(\frac{z_{p F(\phi_x – \phi_y )}}{RT}\) where, yp, xp is the concentration of protein in light and heavy phase, respectively, y1, x1 is concentration of polymer 1 in light and heavy phase, respectively, y2, x2 is concentration of polymer 2 in light and heavy phase, respectively, a1p is second virial coefficient for interaction between protein and polymer 1, a2p is second virial coefficient for interaction between protein and polymer 2, φy, φx is electrical potential for light and heavy phase, respectively, relative to some reference, zp is net surface charge of protein, F is Faraday number, R is gas constant.
10. What is the chemical potential of the solute in the two phases?
a) -μR = μE
b) μR = μE
c) μR = -μE
d) μR ≠ μE
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Explanations: The chemical potential of the solute in the two phases is μR = μE where, μR is the chemical potential of solute in extract, μE is the chemical potential of solute in raffinate. ∴ \(\mu_R^0\) + RTln x = \(\mu_E^0\) + RTln y where, x is the solute concentration in raffinate, y is the solute concentration in extract.
11. What are the steps involved in liquid-liquid extraction?
a) Mixing
b) Settling
c) Phase collection
d) Mixing, settling, phase collection
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Explanation: The three steps involved in liquid-liquid extraction are mixing, settling and phase collection. Mixing involves transfer of solute into two partially immiscible liquids which requires intimate contact of the two. Settling allows the droplets of the dispersed phase to coalesce and gradually leads to separation of two liquid into distinct layers because of difference in density. Phase collection is the separation of phases and collection separately.
Sanfoundry Global Education & Learning Series – Bioseparation Processes.
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