Enzyme Technology Multiple Choice Questions on “Biosensors”.
1. Which of the following statements is not true for biosensors?
A. Biosensors convert a biological signal into an electrical signal
B. Biosensors are used to determine the concentration of substances and other parameters of biological interest even where they do not utilize a biological system directly
C. Biosensors utilize the different biological systems such as enzymes, whole cell metabolism, ligand binding and the antibody-antigen reaction
D. Biosensor consists of a vessel, or series of vessels, used to perform a desired conversion by enzymic means
Answer: D
Clarification: The statements which are true for biosensors are as follows:
• Biosensors convert a biological signal into an electrical signal.
• Biosensors are used to determine the concentration of substances and other parameters of biological interest even where they do not utilize a biological system directly.
• Biosensors utilize the different biological systems such as enzymes, whole cell metabolism, ligand binding and the antibody-antigen reaction.
“Biosensor consists of a vessel, or series of vessels, used to perform a desired conversion by enzymic means” is a false statement. It is true for enzyme reactors.
2. Which of the following features is not possessed by biosensor?
A. The biocatalyst used in the biosensor must be highly specific for the purpose of the analyses
B. The reaction occurring in the biosensor should be as independent of such physical parameters
C. Active site is mainly constituted by non-polar amino acids for catalysis to take place
D. The response from the biosensors should be accurate, precise, reproducible and linear
Answer: C
Clarification: Some of the features possessed by biosensors are discussed below:
• The biocatalyst used in the biosensor must be highly specific for the purpose of the analyses.
• The reaction occurring in the biosensor should be as independent of such physical parameters which allows the analysis of samples with minimal pre-treatment. Also if cofactors or coenzymes are involved, they should also be co-immobilised with the enzyme.
• The response from the biosensors should be accurate, precise, reproducible, linear over the useful analytical range and also free from electrical noise.
“Active site is mainly constituted by non-polar amino acids for catalysis to take place.” This statement is possessed by active site of the enzyme.
3. Which of the following property is not possessed by biosensors?
A. The probe used in the biosensor must be tiny and biocompatible, having no toxic or antigenic effects
B. The biosensor should be cheap, small, portable and capable of being used by semi-skilled operators
C. There should be a market for the biosensor
D. The specificity of substrate binding is mediated by spatial arrangement of atoms in an enzyme’s substrate binding site as well as substrate.
Answer: D
Clarification: Following are the properties which a biosensor should possess:
• If the biosensor used in invasive, the probe must be tiny and biocompatible, having no toxic or antigenic effects.
• The biosensor should be cheap, small, portable and capable of being used by semi-skilled operators.
• If the traditional methods used is encouraged and the decentralization of laboratory testing is discouraged, then there is no use of producing more biosensors. Thus, there should be a market for the biosensor.
“The specificity of substrate binding is mediated by spatial arrangement of atoms in an enzyme’s substrate binding site as well as substrate.” This is a property of active site of the enzyme.
4. Immobilized enzymes are more preferred over free enzymes in producing biosensors.
A. True
B. False
Answer: A
Clarification: Immobilized enzymes are more preferred over free enzymes in producing biosensors because of the following reasons:
• Immobilized enzymes may be re-used ensuring the same catalytic activity for a series of analyses.
• Immobilized enzymes are intrinsically stabled during the immobilization process
• Even if inactivation of enzymes occurs, it is steady and predictable
• Immobilised enzyme systems are re-usable up to 10,000 times over a period of several months which results in a considerable saving in terms of cost of the enzyme in bound state relative to that of free soluble enzymes.
5. What does the following diagram represent?
A. Packed bed reactor
B. Schematic diagram showing the main components of a biosensor
C. Chromatography
D. Lock and key model
Answer: B
Clarification: Biosensors convert a biological signal into an electrical signal. The diagram below represents schematic diagram showing the main components of a biosensor.
In this diagram, the biocatalyst is one which converts the substrate to product. This reaction is determined by the transducer which converts it to an electrical signal. The output from the transducer is amplified, processed and displayed.
6. If the physical change accompanying the reaction is heat output, the biosensors are referred to as _________________
A. potentiometric biosensors
B. optical biosensors
C. calorimetric biosensors
D. amperometric biosensors