Biomedical Instrumentation Multiple Choice Questions on “Respiratory Gas Analysers”.
1. The plasma is a viscous, light red liquid, i.e. almost clear in the fasting stage.
a) True
b) False
Answer: b
Clarification: False, because the plasma is obtained by centrifuging a blood sample. During centrifugation, the heavy blood cells get packed at the bottom of the centrifuge tube and the plasma can thus be separated. The plasma is a viscous, light yellow liquid, i.e. almost clear in the fasting stage.
2. __________ method is based on the absorption of electromagnetic radiation in the visible, ultraviolet and infrared ranges.
a) Cardiotocography
b) Ultrasonic therapy
c) Spectrophotometry
d) Diathermy
Answer: c
Clarification: Spectrophotometry is the most important of all the instrumental methods of analysis in clinical chemistry. This method is based on the absorption of electromagnetic radiation in the visible, ultraviolet and infrared ranges.
3. ________ waves have short wave-length.
a) Microwave
b) Radio wave
c) Gamma rays
d) IR waves
Answer: c
Clarification: Electromagnetic spectrum ranges from very short wavelengths (including gamma and X-rays) to very long wavelengths (including microwaves and broadcast radio waves). The range of wavelength of gamma rays and X-rays is 10-4 to 10 nm. The range of wavelengths of microwaves and radio-waves is 106 to 109 nm.
4. The method based on the absorption of radiation of a substance is known as ________
a) Absorption photometry
b) Spectrophotometry
c) Absorption tocometry
d) Absorption spectrophotoscopy
Answer: d
Clarification: Electronic transitions correspond to the ultraviolet and visible regions, vibrational transitions to the near infrared and infrared regions and rotational transitions to the infrared and far-infrared regions. The method based on the absorption of radiation of a substance is known as Absorption Spectroscopy.
5. The ratio of the radiant power transmitted by a sample to the radiant power incident on the sample is known as ________
a) Absorbance
b) Transmittance
c) Optical density
d) Photometric concentration
Answer: b
Clarification: Let us suppose, Po is the incident radiant energy and P is the energy which is transmitted. The ratio of the radiant power transmitted by a sample to the radiant power incident on the sample is known as the transmittance.
Transmittance = P/Po.
6. If absorbance is plotted graphically against concentration, the graph is _________
a) Parabola
b) Increasing
c) Straight line
d) Decreasing
Answer: c
Clarification: If absorbance is plotted graphically against concentration, a straight line is obtained. A graph derived from the transmittance data will not be a straight line unless transmittance (or percent transmission) is plotted on the log axis of a semi-log paper.
7. ________________ is not a source of radiant energy.
a) Tungsten-mercury lamp
b) Tungsten lamp
c) Xenon-mercury arc
d) Deuterium discharge lamp
Answer: a
Clarification: Radiant just means energy that can move from one place to another without a medium to carry it. A source of radiant energy, which may be a tungsten lamp, a xenon-mercury arc, hydrogen or deuterium discharge lamp, etc.