Question

Sherman is a medical researcher trying to find the causitive agent of a very sick patient with a lung disease. He is

fairly sure that the germ causing the illness is not a bacteria, because saliva samples from the patient have not
grown any bacteria in the lab. He has also not seen any cells under the lab's basic microscope. All signs seem to
be pointing towards the germ being a virus. To know for sure, Sherman needs to see the germ under a
microscope and determine its 3-dimensional shape.
Which type of microscope should Sherman use to try to see the 3-dimensional shape of a virus in the patient's
sample?

A.) Light microscope
B.) Stereomicroscope
C.) Scanning electron microscope
D.) Transmission electron microscope

Answer 1

C.) Scanning electron microscope

Step-by-step explanation:

A scanning electron microscope (SEM) sends a tightly focused beam of electrons over a surface of a sample. The narrow beam gives the SEM a great depth of field and gives the sample a 3D appearance.

With a typical magnification limit of about 100 000×, a SEM can measure particles in the range of 1 nm to 5000 nm with resolutions as good as 1 nm.

Most viruses have diameters ranging from 50 nm to 400 nm, so an SEM is the correct instrument to use.

For example, the Ebola virus has a diameter of 80 nm. The image below is a colourized SEM image of the virus.

A.) is wrong. Most light microscopes have a magnification limit of 1000×.

B.) is wrong. Most stereo microscopes have a maximum magnification of 45×.

D.) is wrong. A transmission electron microscope requires ultra-thin specimens less than 100 nm thick.