This set of Biophysics Multiple Choice Questions & Answers (MCQs) focuses on “Diffusion”.
1. What do you infer from the word diffusion?
a) It’s moving from higher concentration to lower concentration
b) It’s moving from lower concentration to higher concentration
c) It is not getting transported at all
d) It requires ATP
View Answer
Explanation: The process where one molecule moves from its higher concentration to its lower concentration is called a diffusion process. Now the correct answer mentions that the movement of the drug is from a higher to a lower concentration.
2. A protein molecule like albumin can freely diffuse through the biological membrane.
a) True
b) False
View Answer
Explanation: An albumin-like protein is a very big molecule. Now the membrane is so compact that it will not allow such a big molecule for transportation.
3. How the concept of diffusion is applied in pharmaceuticals or drug production?
a) Slow or controlled release of the drug
b) Makings the drug release faster in the human body
c) The information given above is the wrong
d) Making the drug more soluble in blood
View Answer
Explanation: An effective drug must be released into the bloodstream slowly and it should react strongly. Now, to design a slow releasing drug, the knowledge of the diffusion coefficient must be known.
4. Which is not the application of diffusion?
a) The slow release of drug
b) Molecular weight estimation in polymer molecules
c) Determination of absorption and elimination of drugs in the living system
d) Quality control of drugs in terms of their mechanism of action
View Answer
Explanation: The quality of drugs in terms of mechanism of action is determined by enzyme kinetics study (one example out of many) where, how efficiently the drug is binding to the effector molecule, is determined by different biochemical analysis. The rest of the properties can be determined if the diffusion constant of the drug is known.
5. The unit of permeability of a molecule is ____________
a) Cm.S-1
b) Cm-1.S-1
c) Cm-1.S
d) Cm. S
View Answer
Explanation: It is an experimentally determined parameter which is derived from the modified Fick’s law. Rate of diffusion for a membrane having an area of 1 unit and having 1 unit concentration gradient is called permeability of that molecule. Thus experimentally the unit is Cm.S-1.
6. The constant supply of O2 and CO2 across the cell membrane is happened by which of the following process?
a) Active transport
b) Facilitated transport
c) Simple diffusion
d) Facilitated diffusion
View Answer
Explanation: The transport of O2 and CO2 happens due to the difference in partial pressure. During breathing, when we intake air, then the partial pressure of O2 in the lungs is high but the partial pressure of O2 at the blood vessel is low. So O2 from lungs to blood moves through simple diffusion process. The same mechanism is applicable to CO2 transport.
7. Simple diffusion across a biological membrane requires __________
a) ATP
b) GTP
c) No energy
d) ATP or GTP
View Answer
Explanation: ATP is required for uphill transport to molecules that are ATP is used for the transport against a concentration gradient. In a simple diffusion process, no energy is required as downhill transport happens.
8. Which of the following can easily pass through the cell membrane
a) Na+
b) H2O
c) A large polar molecule
d) Zn2+
View Answer
Explanation: A charged molecule cannot pass through the membrane. Secondly, a large polar molecule cannot pass through the membrane because of the presence of the hydrophobic core in the membrane. H2O is very small in size so easily can pass the membrane.
9. Suppose you have made an artificial membrane that is the same as natural. Which of the following molecule do you expect to pass the membrane?
a) A small lipid molecule
b) Ca2+
c) Mg2+
d) Albumin type protein molecule
View Answer
Explanation: A small lipid molecule will pass the membrane because the membrane is hydrophobic so the molecule can directly diffuse through the membrane. Now, Ca2+ and Mg2+ being charged molecule whereas albumin being a large molecule, cannot pass the membrane.
10. What is the vectorial property of diffusion?
a) Molecules move inside to the outside of the cell membrane
b) It has no direction
c) Molecule move higher to lower concentration irrespective of the membrane face
d) Molecules move outside to the inside of the membrane
View Answer
Explanation: That property which has a particular direction is named as vectorial property in physics. The diffusion happens only from higher to lower concentration so it is called as vectorial property.
11. The role of Valinomycin can be correlated with which of the following option?
a) It facilitates channel-mediated passive transport
b) It facilitates active transport
c) It facilitates carrier-mediated diffusion
d) It facilitates energy-dependent diffusion
View Answer
Explanation: Valinomycin is a drug which causes channel formation in the membrane. It helps in the diffusion of K+ molecules across the membrane.
12. Which one is the fastest process?
a) Simple diffusion
b) Facilitated diffusion
c) Active transport
d) Diffusion induced by Valinomycin
View Answer
Explanation: Active transport uses ATP molecules and facilitates the uphill transport of different molecules. Although Facilitate diffusion is faster than simple diffusion it is not faster than active transport.
13. Which of the following process does not require a carrier molecule?
a) Facilitated transport
b) Simple diffusion
c) Active transport
d) Ionophore mediated transport
View Answer
Explanation: Simple diffusion is the direct movement of molecules from higher to lower concentration. This process doesn’t need any type of energy. Simple diffusion is a naturally favored process.
14. The diffusion rate of a biological membrane is 20 units when the concentration gradient across the biological membrane is 40 units. If the concentration gradient of a similar type of biological membrane is 10 units then what is the diffusion rate of this membrane?
a) 5
b) 10
c) 25
d) 50
View Answer
Explanation: According to Fick’s law, the diffusion rate is directly proportional to the concentration gradient across the membrane. So diffusion rate of the second membrane = (20*10) / 40 = 5 units.
15. During the consumption of a drug, the buccal absorption happen. This phenomenon is a type of Diffusion.
a) True
b) False
View Answer
Explanation: During buccal absorption, the concentration of a drug is very high in the buccal cavity but the concentration of that drug is very low in the bloodstream. Therefore, the drug easily gets diffused from the buccal cavity to the bloodstream.
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