Microscopes

Question 1

Compound light microscope

Answer 1

A microscope with a light and glass lenses used to magnify objects. (Compound means more than one type of lens.)

Question 2

Magnification for compound microscope

Answer 2

Eyepiece=10x, low/scanning objective lens=4x, medium objective lens=10x, high objective lens=40x. Up to 2000x.

Question 3

How do you find overall magnification for a compound light microscope?

Answer 3

For overall magnification, multiply eyepiece magnification by chosen lens. Ex: If you use low/scanning objective lens at 4x, then overall magnification is 40x.

Question 4

Resolution

Answer 4

The quality or clarity of an image. You want the highest resolution.

Question 5

What does resolution depend on?

Answer 5

Angular aperture (which we don’t use in PB bio), refractive index (medium/substance light travels through: air or oil), and wavelength of light (shorter wavelength, like violet or blue, gives greater resolution).

Question 6

Making Wet mounts

Answer 6

Place one drop of water on the center of the slide. Place specimen on top. Hold coverslip @ 45 angle above water with one edge resting on the slide. Slowly lower to prevent air bubbles.

Question 7

Air bubbles

Answer 7

They are round and have dark edges under the microscope.

Question 8

Why do you use coverslips for wet mounts?

Answer 8

They protect lens from water, keep specimen in place, and protect the specimen.

Question 9

Field of view

Answer 9

How much of the object you can see.

Question 10

Which lens has the greatest field of view?

Answer 10

The scanning/low objective lens.

Question 11

Stains

Answer 11

Artificial color to make transparent images easier to see.

Question 12

Scanning electron microscope (SEM)

Answer 12

Scans specimen’s surface. Electron beams are used to magnify objects instead of using light. Magnetic lenses and electrons are used to magnify objects up to 250,000x. Metal coating is used on the specimen so that the magnetic lenses will work.

Question 13

Electron microscope (SEM and TEM)

Answer 13

Electron beams are used to magnify objects instead of using light.

Question 14

How much do SEMs cost? What kind of images do they produce?

Answer 14

$30,000-$100,000. The image is 3D and black and white unless color is added later.

Question 15

Transmission electron microscope (TEM)

Answer 15

Transmits electrons through a thin slice of the specimen. Electron beams are used to magnify objects instead of using light. Takes up a whole room. Metal coating on specimen because of magnetic lenses.

Question 16

What does a TEM cost? How much can it magnify an object? What is one thing it can look at and what kind of image is produced?

Answer 16

Costs $100,000-$200,000. Up to 2,000,000x for magnification. 2D black and white image unless computer adds color. Can look at viruses.

Question 17

Microtome

Answer 17

A diamond knife for cutting thin slices.

Question 18

Centrifuge

Answer 18

Spins substances like blood to either mix or separate them; it depends on the substance.

Question 19

Cell culture

Answer 19

Growing cells in a lab.

Question 20

Nosepiece

Answer 20

Holds the objective lenses above the stage and rotates so that all lenses may be used.

Question 21

Diaphragm

Answer 21

Adjusts the amount of light passing through the slide and into the lens.

Question 22

Base and arm

Answer 22

Base supports the microscope; arm supports the body above the stage.

Question 23

Stage clip

Answer 23

Holds a slide in place on the stage.

Question 24

Body

Answer 24

Separates the lens in the eyepiece from the objective lenses below.

Question 25

Stage

Answer 25

Supports the object being viewed.

Question 26

Light source

Answer 26

Illuminates specimen being viewed.

Question 27

Coarse adjustment

Answer 27

Used to focus the image of an object when it is viewed through the scanning and low-power lenses.

Question 28

Fine adjustment

Answer 28

Used to focus when using the high power lens.