This set of Cell Biology online quiz focuses on “Techniques – SEM and AFM”.
1. The scanning electron microscope is used to examine _____________
d) cell surfaces
Explanation: The scanning electron microscopy (SEM) is a type of electron microscopy used to examine the surface morphologies of various types of cells. The electrons are reflected back from the surface of the specimen, delivering details about its surface.
2. In the preparation of samples for SEM, the specimens are air-dried by a process of critical-point drying.
Explanation: For sample preparation of SEM, the basic requirement is producing specimen that has the same shape and surface properties as that of the living cell and at the same time is devoid of any fluid for viewing under the vacuum.
3. At the critical drying point, there is no surface tension between ________________
a) gas and oil
b) gas and liquid
c) liquid and liquid
d) oil and liquid
Explanation: Critical drying point is the technique used to prepare samples for the scanning electron microscopy (SEM). At this point the density of the liquid and the gas is equal and hence there is no surface tension between the two.
4. In SEM, the image is formed by the electrons that _________________
a) reflect back
c) undergo inversion
d) pass through
Explanation: Unlike in transmission electron microscopy (TEM) in which image is formed when the electrons pass through the sample, in case of scanning electron microscope the electrons are reflected back and that leads to the formation of an image.
5. The AFM uses a _______________ to scan the surface of a molecule.
a) X-ray film
b) Nanosized tip
c) Non-metal tip
Explanation: The atomic force microscope (AFM) uses a nanosized tip that probes the surface of materials. Atomic force microscopy is a technique of importance in molecular biology and nanotechnology.
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