1.1 World Of The Microscope

Question 1

magnification

Answer 1

The number of times bigger the image looks compared to the real object

Question 2

image

Answer 2

what you see when you look through the microscope; the image of the real object appears magnified

Question 3

real object

Answer 3

the specimen you put under the microscope

Question 4

magnification =

Answer 4

magnification = size of image/ size of real object

Question 5

size of image =

Answer 5

magnification x size of real object

Question 6

size of real object =

Answer 6

size of image/ magnification

Question 7

Resolving power

Answer 7

The measure of the ability to distinguish two separate points that are very close together

Question 8

How does a light microscope work and what is its maximum magnification?

Answer 8

Uses a beam of light to form an image of an object and can magnify up to 2000 times

Question 9

What are some advantages of the light microscope?

Answer 9

Relatively cheap
Easy to use
Can be used almost anywhere
Can magnify live specimens

Question 10

What are some disadvantages of the light microscope?

Answer 10

Magnification isn’t very high: you can see cells and some structures but not the details of organelles

Question 11

When was the electron microscope invented?

Answer 11

In the 1930s

Question 12

How does an electron microscope work and what is the maximum magnification?

Answer 12

Electron microscopes use a beam of electrons to form an image and can magnify and object up to around 2,000,000 times

Question 13

What are some advantages of the electron microscope?

Answer 13

• Scanning electron microscope can create dramatic 3d images
• Transmission electron microscope has very high magnification

Question 14

What are some disadvantages of the electron microscope?

Answer 14

• Very expensive
• Hard to use
• Has to be kept in temperature, pressure and humidity-controlled room
• Can’t magnify live specimens (specimen has to be kept in a vacuum)

Question 15

What is the difference between magnification and resolution?

Answer 15

Magnification refers to the degree of enlargement of an object. Resolution is the ability to distinguish between 2 points in an object, showing how clear and sharp the image is.

Question 16

Compare and contrast the magnification and resolution obtained by using light and electron microscopes.

Answer 16

Light microscopes use visible light and have lower magnification and resolution compared to electron microscopes, which use electron beams. Electron microscopes provide higher magnification and resolution, allowing for detailed imaging of smaller structures compared to light microscopes.

Question 17

Evaluate the use of an electron microscope and a light microscope, giving one example where each type of microscope might be used.

Answer 17

Electron microscopes
magnify up to around ×2 000 000
have a resolving power of about 10 nm (scanning electron microscope) or 0.2 nm (transmission electron microscope)
may be used to examine subcellular structures (e.g., chromosomes during cell division)
light microscopes
magnify up to around ×2 000
have a resolving power of about 200 nm
may be used to look at cells dividing (e.g., stained onion cells)

Question 18

Explain the importance of microscopes in the development of our understanding in cell biology

Answer 18

Without microscopes we cannot see most cells.
Light microscopes
- show cellular structure of living organisms and some subcellular structures (e.g., nucleus and chloroplasts)
- allow observation of living cells and staining of cells to show different features
Electron microscopes
-enable examination of cells in great detail
- help determine what goes on within individual body cells
- can only be used for dead specimens in a vacuum

Question 19

When we’re the fist light microscopes developed?

Answer 19

Mid 17th century

Question 20

Why would you have to change the objective lens to its lowest

Answer 20

Easier to focus and gives largest field of view

Question 21

How could you adjust a microscope to see an object more clearly?

Answer 21

TURN the fine focus knob

Question 22

What is the magnification and resolving power of a light microscope?

Answer 22

Magnification: x2000
Resolving power: 200nm

Question 23

What is the magnification and resolving power of an electron microscope?

Answer 23

Magnification: x2,000,000
Resolving power: 10nm(SEM), 0.2nm (TEM)