Parts and functions of microscope

Question 1

Arm

Answer 1

Connects the ocular to the rest of the microscope

Question 2

Base

Answer 2

Provides a stable platform for the microscope

Question 3

Body tube

Answer 3

Connects the ocular lenses to the arm

Question 4

Ocular lens

Answer 4

Used to view the specimen

Question 5

Stage clip

Answer 5

Holds the slide or specimen in place

Question 6

Objective lens

Answer 6

Used to magnify the specimen for examination

Question 7

Lamp/light

Answer 7

Provides light that will pass through the specimen enabling viewer to view specimen

Question 8

Light switch

Answer 8

Turns on the lamp

Question 9

Rheostat

Answer 9

Allows the operator to adjust the lamps output

Question 10

Mechanical stage

Answer 10

The platform on which the glass slide containing the specimen rest. Has Clips and now I’m stuck with the slide in place/move side to side

Question 11

Mechanical stage control knobs

Answer 11

Moves slide up and down and side to side

Question 12

Iris diaphragm control lever

Answer 12

Adjust the amount of light passing through the specimen

Question 13

Revolving nose piece

Answer 13

Holds the various objective lenses. Revolves to let user switch from lens to lens

Question 14

Substage condenser

Answer 14

Focuses light on the specimen

Question 15

Coarse adjustment knob

Answer 15

Raises/lower stage and large increments to focus specimen

Question 16

Fine adjustment knob

Answer 16

Raises/lowers stage in very small increments

Question 17

Diopter adjustment ring

Answer 17

Allows compensation for differences between the users two eyes

Question 18

Resolution

Answer 18

Refers to a lens’s ability to distinguish between objects that are close together

Question 19

Contrast

Answer 19

Refers to the differences in color& light between parts of an object or between an object and its background.

Question 20

Parfocal

Answer 20

Refers to different eyepieces that all focus their images in the same plane, so they can be interchanged without adjusting.

Question 21

If you are using the oil immersion lens, how can resolution increase?

Answer 21

Oil has a greater refractive index than air, giving it more resolving power.

Question 22

Why must immersion oil be used with the oil immersion lens?

Answer 22

Immersion oil is only used with 100X because examining a specimen on different power would not provide enough resolution.

Question 23

How does immersion oil increase resolution with the oil immersion lens?

Answer 23

Light does not bend as much through oil as it does glass.(air RI = 1.00, oil RI = 1.52)

Question 24

How can one increase contrast working with wet mounts?

Answer 24

Staining can increase contrast when working with wet mounts?

Question 25

Describe the proper way to examine a bacterial smear, beginning with the scanning lens and working up to the oil immersion lens.

Answer 25

Use the stage controls to move the slide until plate from lamp passes through the specimen, focus specimen with course adjustment using find adjustment for sharp image. Move the lens up to 100 X using rheostat to adjust light.

Question 26

How does one properly clean lenses and prepare the microscope to be returned to the microscope cabinet?

Answer 26

Clean the lenses with lens paper until no oil is present. Lower stage to lowest position, move the stage clips so it is flush with the left side. Remove the slide, return objective lens to 4X. Turn off the power, return the rheostat to one. Wrap the cord around the arm and leg.

Question 27

Procedure for making a wet mount

Answer 27

Place a drop of water on slide. Then place specimen in water. Next place a clean coverslip at a 45° angle and fall to the side. Finally examine the specimen identifying structures.

Question 28

What are the advantages of a wet mount over a heat fixed and stained smear?

Answer 28

Wet mounts allow us to examine living specimens while staining usually kills the specimen.

Question 29

What is the “field of view”.

Answer 29

The area that can be viewed at one time through a given object.

Question 30

Describe Endosymbiotic theory

Answer 30

A model for the evolution of eukaryotes which states that organelles arose from prokaryotic cells living inside a host prokaryote

Question 31

What is the relationship between primitive cyanobacteria and eukaryotic chloroplasts?

Answer 31

The cyanobacteria evolved to become the chloroplasts. Chloroplasts may be descendants of photosynthetic prokaryotes ingested by an ancestral eukaryote.