Module 2 Section 1 - Microscopy

Question 1

what is magnification

Answer 1

how much bigger the image is than the specimen (the sample your looking at)

Question 2

what do microscopes produce

Answer 2

a magnified image

Question 3

how is magnification calculated

Answer 3

magnification = image size / object size

Question 4

what is resoultion

Answer 4

how well a microscope distinguishes between two separate points that are close together

Question 5

if a microscope cant separate two separate objects then….

Answer 5

increasing the magnification wont help

Question 6

what is the formula triangle which has image size, magnification and obejct size

Answer 6

image size
magnification x object size

Question 7

what are three microscopes we need to know

Answer 7

-light microscopes
-laser scanning confocal microscopes
-electron microscopes

Question 8

what does a light microscope use to form images

Answer 8

light

Question 9

what is said about the resolution of light microscopes

Answer 9

lower than electron microscopes

Question 10

what are light microscopes usually used for

Answer 10

whole cells or tissues

Question 11

what is typically the maximum useful magnification of light microscopes

Answer 11

x1500

Question 12

what do laser scanning microscopes use to from images

Answer 12

laser beams (usually tagged with fluorescent dye)

Question 13

what does thee laser do the dye

Answer 13

gives off light - light is then focused through a pinhole onto a detector

Question 14

what happens after light is focused on the detector

Answer 14

detector hooked up to a computer which generates an image - image can be 3D

Question 15

what does the pinhole mean

Answer 15

any out of focus light is blocked meaning microscope produces a much clearer image

Question 16

what can these microscopes also be for?

Answer 16

looking at different depths in thick specimens

Question 17

what do electron microscopes use to form images

Answer 17

electrons

Question 18

what two kinds of electron microscopes are there

Answer 18

-transmission electron microscope (TEM)
-Scanning electron microscope (SEM)

Question 19

what do transmission electron microscopes use to form images

Answer 19

electromagnets to focus a beam of electrons which is transmitted through the specimen

Question 20

why do some parts f TEM image look darker than others

Answer 20

because they are denser

Question 21

why are TEMs good

Answer 21

they provide high resolution images

Question 22

Why are TEMs not so good

Answer 22

Can only be used on thin specimens

Question 23

How do SEMs form images

Answer 23

They scan a beams of electrons across a specimen which knocks off electrons from the specimen gathered in a cathode ray tube to form an image

Question 24

Why are SEMs good

Answer 24

Shows the surface of the specimen and can be 3D

Question 25

What is the maximum resolution of a light microscope

Answer 25

0.2 micrometers

Question 26

What is the maximum resolution of TEMs

Answer 26

0.0002 micrometers

Question 27

What is the maximum resolution of SEMs

Answer 27

0.002 micrometers

Question 28

What is the maximum magnification of light microscopes

Answer 28

x 1500

Question 29

What the maximum magnification of TEMs

Answer 29

Can be more than x1 000 000

Question 30

What is the maximum magnification of SEMs

Answer 30

Usually less than x 500 000

Question 31

Why do you need to stain samples

Answer 31

Objects being viewed may be transparent so you stain the sample so components of the cell can be viewed

Question 32

What type of staining is used for light microscopes

Answer 32

Some sort of dye

Question 33

Different stains …..

Answer 33

Are used to make different things show up. More than one stain can be used at once

Question 34

What type of staining is used for electron microscopes

Answer 34

Objects are dipped in a solution of heavy metals

Question 35

Why are sample for electron microscopes dipped in heavy metals

Answer 35

The metal ions scatter the electrons, again creating contrast

Question 36

What do you need to view a specimen under a light microscope

Answer 36

A microscope slide

Question 37

What are the different types of slides

Answer 37

Dry Mount Wet Mount

Question 38

What is a dry mount

Answer 38

A specimen that is placed on a slide with or without a coverslip over it.

Question 39

What is wet mount

Answer 39

A specimen is placed on a drop of water on the slide, with a coverslip placed over it

Question 40

What is the first stage of using a microscope

Answer 40

-Clip the slide on the stage

Question 41

What is the second stage of using a microscope

Answer 41

Select the lowest powered objective lens

Question 42

What is the third stage of using a light microscope

Answer 42

Use the coarse adjustment knob to bring the stage just below the objective lens

Question 43

What is the fourth stage of using a light microscope

Answer 43

Look down the eyepiece, use the coarse adjustment knob to move the stage downwards until the image is roughly in focus

Question 44

What is the fifth stage of using a light microscope

Answer 44

Adjust the fine adjustment knob to focus until a clear image shows

Question 45

What is the sixth stage of using a light microscope

Answer 45

You can see the specimens under a greater magnification by swapping to a higher powered objective lens and refocus

Question 46

What is the eyepiece graticule used for

Answer 46

Finding the size of the specimen

Question 47

Where is the eyepiece graticule fitted

Answer 47

Onto the eyepiece

Question 48

What is a stage micrometer used for

Answer 48

Used to work out the value of the divisions of the eyepiece graticule at a particular magnification

Question 49

Why is the eyepiece graticule described as a transparent ruler

Answer 49

It is like a ruler but with no units or numbers