A scientist wants to examine living cells lining the respiratory tract to determine how the cells use tiny hairs to move dirt an
d mucus away from the lungs. Which one of the following instruments would be best, and why? A. a light microscope, because it allows observations of whole, live cells
B. a transmission electron microscope, because it has high resolving power
C. a transmission electron microscope because it is capable of very high magnification
D. a scanning electron microscope, because it can reveal structures on cell surfaces
E. a scanning electron microscope, because it can be used to observe whole cells without slicing them
Answer: A light microscope, because it allows observation of whole, live cells
Explanation: The electron microscopes (transmission and scanning) cannot and should not be used with living cells because the electrons utilized will destroy the living cell. It is important to highlight the differences between the three types of microscopes listed above. The transmission electron microscope uses <em>electrons </em>to create an image through the sample which can be magnified and focused onto a device than can then produce an image. The <em>scanning electron</em> microscope uses electrons to provide an image by scanning the sample. The light microscope is the normal microscope that is used in all laboratories. As stated in the name, light microscopes use light and magnifying lenses to view the sample. The light and lenses allow the sample to not be affected if it is a living sample.
<span>The burners must be turned off because, in the case of liquid chromatography, the eluant solvents being used are flammable. Leaving the burners lit could cause the eluant to catch on fire, putting the scientist at risk.</span>
In animals, oxygen combines with food in the cells to produce energy for daily activity and then gives off carbon. The carbon combines with oxygen to form carbon dioxide (CO2) and is released back into the atmosphere as a waste product when animals breathe and exhale.
