Histology Testbank: Microscope 2a

Instructions: For each histology question, pick the one best answer. This histology test bank is also useful for the histology questions on the USMLE (USMLE step 1).

1.
When using a compound microscope, what is the magnification of the oil immersion lens?
a. 4X
b. 10X
c. 40X
d. 100X
e. 1000X

Answer: d

A compound microscope has two lenses: an eyepiece lens and objective lens. The eyepiece lens usually has a magnification of 10X. There are objective lenses on the revolving nosepiece with varying magnifications. Most compound microscopes have objective lenses with magnification of 4X, 10X, and 40X. Some compound microscopes also have an oil immersion lens with a magnification of 100X.

2.
What is the usual magnification of the ocular lens on a compound microscope?
a. 1X
b. 10X
c. 100X
d. 1000X
e. 10,000 X

Answer: b

The usual magnification of an ocular lens on a compound microscope is 10X. Some microscopes have a 15X eyepiece lens. The ocular lens is the lens at the top of the tube, the one that you first look through when using a microscope. It is also called the eyepiece lens.

3.
When using oil immersion to view a tissue, what is the refractive index of the oil?
a. Zero
b. Same as air
c. Same as glass
d. Same as water
e. None of the above

Answer: c

With light microscopy, there normally is a space of air between the slide and the lens. Oil immersion replaces that space of air with oil. The refractive index of the oil is the same as glass.

4.
What is the role of the condenser lens?
a. Control the aperture of light
b. Increase the magnification
c. Focus the light on the specimen
d. Initial magnification of 10X
e. Provide light

Answer: c

The role of the condenser lens is to focus light on the specimen. It is used with higher magnifications.

5.
On a microscope, what structure varies the diameter of the cone of light?
a. Base
b. Nosepiece
c. Stage
d. Tube
e. Diaphragm

Answer: e

The base is the bottom of the microscope. The revolving nosepiece is also called a turret. The objective lens are attached to the nosepiece (or turret). The slide rests on the stage. The tube is the structure which connects the eyepiece to the objective lenses (it is shaped like a tube; thus, its name). The diaphragm controls the diameter of the cone of light.

6.
Where do you place the slide when using a microscope?
a. Base
b. Nosepiece
c. Stage
d. Tube
e. Diaphragm

Answer: c

The base is the bottom of the microscope. The revolving nosepiece is also called a turret. The objective lens are attached to the nosepiece (or turret). The slide rests on the stage. The tube is the structure which connects the eyepiece to the objective lenses (it is shaped like a tube; thus, its name). The diaphragm controls the diameter of the cone of light.

7.
What is the bottom of a microscope called?
a. Base
b. Nosepiece
c. Stage
d. Tube
e. Diaphragm

Answer: a

The base is the bottom of the microscope. The revolving nosepiece is also called a turret. The objective lens are attached to the nosepiece (or turret). The slide rests on the stage. The tube is the structure which connects the eyepiece to the objective lenses (it is shaped like a tube; thus, its name). The diaphragm controls the diameter of the cone of light.

8.
What is another name for the bright field microscope?
a. Simple microscope
b. Compound microscope
c. Phase contrast microscope
d. Dissection microscope
e. Transmission electron microscope

Answer: b

A simple microscope has only one lens. A compound microscope utilizes two lenses: an ocular lens and an objective lens. The compound microscope is also referred to as a "light microscope" or "bright field microscope". A phase contrast microscope is useful for examining living cells, because the specimen does not need to be stained. A dissection microscope uses low power magnification. Things appear three dimensional with a dissection microscope. A transmission electron microscope does not use light, but rather a beam of electrons.

9.
Which microscope would be particularly useful for looking at living cells?
a. Simple microscope
b. Compound microscope
c. Phase contrast microscope
d. Dissection microscope
e. Transmission electron microscope

Answer: c

A simple microscope has only one lens. A compound microscope utilizes two lenses: an ocular lens and an objective lens. The compound microscope is also referred to as a "light microscope" or "bright field microscope". A phase contrast microscope is useful for examining living cells, because the specimen does not need to be stained. A dissection microscope uses low power magnification. Things appear three dimensional with a dissection microscope. A transmission electron microscope does not use light, but rather a beam of electrons.

10.
Which type of microscope has only one lens?
a. Simple microscope
b. Compound microscope
c. Phase contrast microscope
d. Dissection microscope
e. Transmission electron microscope

Answer: a

A simple microscope has only one lens. A compound microscope utilizes two lenses: an ocular lens and an objective lens. The compound microscope is also referred to as a "light microscope" or "bright field microscope". A phase contrast microscope is useful for examining living cells, because the specimen does not need to be stained. A dissection microscope uses low power magnification. Things appear three dimensional with a dissection microscope. A transmission electron microscope does not use light, but rather a beam of electrons.