Enzyme Technology Questions and Answers – Optical Biosensors and Piezoelectric Biosensors

This set of Enzyme Technology Multiple Choice Questions & Answers (MCQs) focuses on “Optical Biosensors and Piezoelectric Biosensors”.

1. There are two main areas of development in optical biosensors.
a) True
b) False

Explanation: In optical biosensors, there are two main areas in which development can happen. Firstly, the measurement of changes in light absorption between the reactant and product of a reaction. These use colorimetric test strips to measure the change. These strips are single-use cellulose pads which are impregnated with enzyme and reagents. These strips are disposable ones. Secondly, the measurement of light output by luminescent process. Hence the above statement is true.

2. Which of the following technology is used for whole-blood monitoring in diabetes control?
a) Amperometric biosensor
b) Potentiometric biosensor
c) Optical biosensor
d) Calorimetric biosensor

Explanation: Optical biosensor is used for whole-blood monitoring in diabetes control. In this case, the strips include glucose oxidase, horseradish peroxidase and a chromogen. The hydrogen peroxide, produced by the aerobic oxidation of glucose, oxidizes weakly colored chromogen to a highly colored dye.

3. What does ‘X’ represent in the reaction?
Chromogen (2H) + H2O2 $$\underset{X}{\rightarrow}$$ Dye + 2H2O
a) Urease
b) Luciferase
c) Peroxidase
d) Penicillinase

Explanation: In the above reaction, ‘X’ represents peroxidases which oxidizes hydrogen peroxide to water and chromogen to dye. Urease acts on urea. Luciferase is an enzyme which produces luminescence. Penicillinase is an enzyme which acts on penicillin.

4. Luciferase is obtained from ________
a) firefly
b) yeast
c) bacillus acidopullulyticus
d) malted barley

Explanation: Luciferase is obtained from firefly. Luciferase is also called Photinus-luciferin 4-monooxygenase and it produces luminescence. Yeast is used to obtain invertase. Pullulanase is obtained from Bacillus acidopullulyticus, whereas β-amylases is obtained from malted barley.

5. _______________ is used to detect the presence of bacteria in food or clinical samples.
a) Proteolytic enzymes
b) Luciferase
c) Rennet
d) Glucoamylase

Explanation: Luciferase is used to detect the presence of bacteria in food or clinical samples. Proteolytic enzymes are used in meat tenderization. Rennet is used in cheese making. Glucoamylase is used in glucose syrups.

6. What does ‘Y’ represent in the following reaction?
ATP + Y + O2 $$\underset{Luciferase}{\rightarrow}$$ Oxyluciferin + AMP + pyrophosphate + CO2 + light
a) Esters
b) Hydrogen peroxide
c) D – luciferin
d) Uric acid

Explanation: In the above reaction, ‘Y’ represents D-luciferin. In the above reaction, ATP released from lysed bacteria reacts with D-luciferin and oxygen in a reaction that produces yellow light in high quantum yield. Ester is the substrate on which chymotrypsin acts. Catalase acts on hydrogen peroxide, whereas uricase acts on uric acid.

7. What does the following equation represent?
$$∆f=\frac{Kf^2 ∆m}{A}$$
a) Frequency change
b) Current
c) Electrical resistance
d) Electrical potential

Explanation: The resonant frequency changes as molecules adsorb or desorb from the surface of the crystal, obeying the relationship,
$$∆f=\frac{Kf^2 ∆m}{A}$$, where
Δf = change in resonant frequency (Hz), Δm = change in mass of adsorbed material (g), K = crystal dependent constant and A = adsorbing surface area.

8. Which of the following biosensor is a formaldehyde biosensor?
a) Calorimetric biosensor
b) Potentiometric biosensor
c) Optical biosensor
d) Piezo-electric biosensor

Explanation: Formaldehyde biosensor is a piezo-electric biosensor that utilizes a formaldehyde dehydrogenase coating immobilised to a quartz crystal and sensitive to gaseous formaldehyde. Calorimetric biosensor involves measuring the heat generated during a reaction using thermistors. Potentiometric biosensors make use of ion-selective electrodes in order to transduce the biological reaction into an electrical signal. Optical biosensors involve determining changes in light absorption between the reactants and products of a reaction or measuring the light output.

9. Which of the following is a drawback of formaldehyde biosensor?
a) Inexpensive
b) Small and robust
c) Difficulty in the determination of material in solution
d) Rapid response

Explanation: The major drawback of formaldehyde biosensor is interference from atmospheric humidity which will make it difficult for the determination of material in solution. The advantages are as follows:
* Inexpensive.
* Small and robust.
* Capable of giving a rapid response.

Sanfoundry Global Education & Learning Series – Enzyme Technology.