# Biological Material Questions and Answers – Diffusivity, Osmotic Pressure and Sedimentation Coefficient

This set of Bioseparation Technology Multiple Choice Questions & Answers (MCQs) focuses on “Biological Material Properties – Diffusivity, Osmotic Pressure and Sedimentation Coefficient”.

1. The random movement of molecule which is caused by intermolecular collision is called ___
a) Diffusivity
b) Solubility
c) Electrostatic Charge
d) Osmotic Pressure

Explanation: Diffusivity is a random movement of particles due to random intermolecular collision. The migration of particles is from the higher concentration to the lower concentration. It is one of the important parameter for bioseparation as it helps in mass transfer.

2. What is diffusion coefficient?
a) Measure of solubility of molecule
b) Measure of movement of molecule
c) Measure of dispersion of molecules
d) Measure of electrostatic charges of the molecule

Explanation: Diffusion coefficient is the measurement of the molecule’s movement in the suspension. The mobility of the molecules is directly proportional to the diffusion coefficient, when the diffusion coefficient is more; the mobility of molecule is also more when the molecules move from region of higher concentration to the region of lower concentration.

3. What are the parameters that influence the diffusivity of molecule in the solution?
a) Size, friction factor, viscosity
b) Charge, size, molecular weight
c) Molecular weight, friction factor, viscosity
d) Charge, friction factor, viscosity

Explanation: The molecular weight along with friction factor and the diffusivity of the molecule influences the diffusivity of the molecule. If the molecular weight of molecule is more it will not take long time to move from one region to another, if the molecule is viscous its movement from region of higher concentration to region of lower concentration will be hindered, if the friction is more in the molecule, its movement will be hindered.

4. The friction factor is independent on shape of the molecule as well as on the degree of hydration.
a) True
b) False

Explanation: The friction factor depends on the structure of the molecule and the degree of hydration of molecule in an aqueous system. The movement of molecule will be improper if the frictional force is too less or very high and the diffusion will also be hindered because of the hydration of the molecule, if the molecule is less hydrated it will have less frictional force and hence will face improper diffusion.

5. What is the diffusivity of glycerol in water?
a) 2.5 * 10-9 m2/s
b) 1.35 * 10-9 m2/s
c) 1.19 * 10-9 m2/s
d) 7.2 * 10-10 m2/s

Explanation: The diffusivity of glycerol is 7.2 * 10-10 m2/s. The diffusivity of sodium chloride is 2.5 * 10-9 m2/s. The diffusivity of urea is 1.35 * 10-9 m2/s. The diffusivity of acetic acid is 1.19 * 10-9 m2/s.

6. Predict the diffusivity of a molecule which has twice the radius of another molecule in same solution, if the diffusivity of another molecule is 5.5 * 10-11 m2/s and its radius is 4nm.
a) 1.375 * 10-11 m2/s
b) 1.5 * 10-11 m2/s
c) 1.375 * 10-15 m2/s
d) 1.5 * 10-15 m2/s

Explanation: The diffusivity will be calculated using, $$\frac{r1}{r2} = \frac{D2}{D1}$$ equation where r1 and r2 are the radius and D1 and D2 are the diffusivity. So using the given values in the question, D2 = $$\frac{5.5 * 10^{-11}}{4}$$ = 1.375 * 10-11 m2/s.

7. The tendency of bigger molecules to settle in a solution is called _____________
a) Centrifugation
b) Decantation
c) Sedimentation

Explanation: Sedimentation is the process of settling of large solid particles in a liquid medium. Centrifugation is based on the process of sedimentation under the influence of gravitational field generated by rotation. Decantation is based on the process of sedimentation under the effect of gravity. Adsorption does not follow the process of sedimentation; it is the process in which the solid particle absorbs the molecule.

8. The rate of settling in centrifugation depends on ___________
a) only geometry of vessel and the speed of rotation
b) only geometry of vessel and location of vessel
c) only speed of rotation
d) geometry of vessel, location in the vessel, speed of rotation

Explanation: The settling of particles under the gravitational force in centrifugation depends on not only the speed of rotation of the vessel but also the shape and volume of vessel, position of vessel and the size of vessel.

9. Sedimentation coefficient of collagen is __________
a) 6.43
b) 1.17
c) 2.54
d) 4.5

Explanation: Sedimentation coefficient of collagen is 6.43. Sedimentation coefficient of cytochrome c is 1.17. Sedimentation coefficient of chymotrypsinogen is 2.54. Sedimentation coefficient of alpha amylase is 4.5.

10. What are the correlated properties of sedimentation coefficient?
a) Temperature, pressure, volume
b) Frictional factor, molecular weight, molar volume, density
c) Temperature, pressure, charge
d) Volume, weight, pressure

Explanation: The sedimentation coefficient is correlated with frictional factor, molecular weight, molar volume and the density. Since, S = $$\frac{M (1-v \rho)}{f}$$ where, M is the molecular weight, v is the molar volume, ρ is the density and f is the frictional factor of the molecule.

11. What will be the sedimentation coefficient of a particle which is settled at the velocity of 1m/s having angular velocity 2.5 radians/s and the distance of particle from the axis of rotation was 2m?
a) 1.08
b) 2.08
c) 0.08
d) 3.08

Explanation: s = $$\frac{v}{\omega^2 r}$$ where, S is the sedimentation coefficient, ω is the angular velocity, r is the distance of particle from the axis of rotation. Therefore sedimentation coefficient of the particle is 0.08.

12. Who initially described the concept of osmotic pressure?
a) Watson and Crick
b) G. Mendel
c) C. V. Raman
d) Jean-Antoine Nollet

Explanation: Jean-Antoine Nollet a French physicist initially described the concept of osmotic pressure in the 18th century. Watson and crick discovered DNA. G. Mendel gave the theories of Heredity. C. V. Raman discovered Raman Effect.

13. Which bioseparation process has the role of osmotic pressure in separation?
a) Membrane separation
b) Filtration
c) Sedimentation
d) Centrifugation

Explanation: Osmotic pressure is the pressure generated across the membrane when a solution is separated from a concentrated solution by a semi-permeable membrane. The pressure is generated because of the flow of liquid from the region of lower concentration to the region of higher concentration.

14. What will be the osmotic pressure of the solute having concentration of 2.5 kg-mole/m3?
a) 560.036 atm
b) 56.036 atm
c) 5603.6 atm
d) 5.603 atm

Explanation: π = R. T. c, where R is the gas constant which is 0.08206 L atm /mol/K, T is absolute temperature which is 273.15K, c is the concentration of solute which is given in the question as 2.5mol/L. Therefore, π = 56.036 atm.

15. What is the osmotic pressure difference across the membrane, if the osmotic pressure at inlet is 2.5atm and at outlet is 5.5atm?
a) 3.5atm
b) 2atm
c) 3atm
d) 2.5atm

Explanation: The difference in osmotic pressure across the membrane is given by Δπ = π1 – π2. Therefore Δπ = 5.5atm – 2.5atm = 3atm.

Sanfoundry Global Education & Learning Series – Bioseparation Technology.

To practice all areas of Bioseparation Technology, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]