Microscopes Flashcards

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1
Q

What do we need microscopes for?

A

To study most cells

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2
Q

What are the two types of microscopes?

A

Light and electron

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3
Q

When is light microscopes used?

A

When relativity low magnification and resolution is enough

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4
Q

What are light microscopes used to study?

A

Living cells

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5
Q

What type of microscope is for regular use?

A

Light

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6
Q

What do electron microscopes provide higher than light microscopes?

A

Magnification and resolution images

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7
Q

What can’t electron microscopes be used to view?

A

Living cells

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8
Q

What happened in the 1590s to develop light microscopes?

A

Janssen experimented with putting lenses in tubes- the first compound microscope.

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9
Q

How magnified we’re the 1590s compound microscopes thought to have magnified to?

A

3x to 9x

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10
Q

What happened in 1650s to develop light microscopes?

A

British scientist Robert Hooke observed and drew cells using a compound microscope

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11
Q

What happened in the late 1600s to develop light microscopes?

A

Antonio can Leeuwenhoek constructed a microscope with a single spherical lens

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12
Q

How magnified was the late 1600s microscope?

A

X275

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13
Q

What’s the maximum magnification of a light microscope today?

A

X2000

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14
Q

How magnified are light microscopes usually used in schools?

A

X400

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15
Q

Name the components of a light microscope

A

Eyepiece
Coarse focus
Objective lenses
Stage clip
Condenser
Mirror
Fine focus
Arm
Stage

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16
Q

Give the formula for calculating the magnification of light microscopes

A

Magnification of the microscope=magnification of the eye piece X magnification of the objective

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17
Q

If the magnification of an eye piece is x10 and the objective is x4, what’s the magnification of the microscope? Give working out

A

10 X 4 = 40

18
Q

Give the formula for calculating magnification

A

Magnification= size of image/real size I object (I= a/m) (I AM)

19
Q

If the real size of a cell is 0.05mm and the real size is 100mm, what’s it’s magnification? Give working out

A

100/0.05=2000mm

20
Q

What’s the aim for preparing light microscope slides?

A

To prepare and stain cells for examination with a light microscope

21
Q

What’s the small square of circle of thin glass called that’s placed over the specimen?

A

Coverslip

22
Q

What’s does the coverslip do?

A

Prevents the slide from drying out when it’s being examined

23
Q

What’s does iodine do?

A

Stain plant cells to make the internal structures more visible

24
Q

What dye is used to stain cheek cells?

A

Methylene blue

25
Q

Name the risks of a light microscope (preparing a slide) practical

A

-care must be taken when looking down the microscope if the illumination is too bright
-care when using microscope stains
-care when handling coverslips and microscope slides

26
Q

What do electron microscopes use to work?

A

A beam of electrons

27
Q

Why can’t living cells be observed using an electron microscope??

A

Samples are placed in a vacuum

28
Q

What are the two types of electron microscopes?

A

Transmission electron microscope (TEM)
Scanning electron microscope(SEM)

29
Q

What is the TEM microscope used to examine?

A

Thin slices or sections of cells or tissues

30
Q

What is the SEM microscope used to examine?

A

Surface structure of specimens

31
Q

Why can the SEM microscope be used to examine the surface structure of specimens?

A

It has a large depth of field

32
Q

What’s the TEMs maximum magnification?

A

X1000000

33
Q

What’s the limit of a TEM?

A

Less than 1nm

34
Q

If we’re comparing the size of a bacteria cell with a HIV. The bacterium is 1000nm and the HIV is 100nm. Work out the size difference.

A

1000nm/100nm= 10
The length of the bacterium is 10 times that of the HIV

35
Q

What do magnitudes go up in?

A

Factors of 10

36
Q

Give examples of numbers in the magnitude 10^2

A

200,300

37
Q

Give examples of numbers in the magnitude 10^3

A

2000,3000

38
Q

What’s the aim/s of the practical- analysing biological specimens using microscopes?

A

-to use a light microscope to examine animal and or plant cells
-to make observations and draw scale diagrams of cells

39
Q

Give the method for analysing biological specimens using microscopes.

A

1) rotate the objectives so that the low power objective lens(eg. X10)is in line with the stage
2) turn the coarse focus to adjust the space between the stage and the objective lens
3)place the microscope slide on the stage. Line it up so that the specimen is in the centre of the stage, where the light passes through
4) focus the slide by turning the coarse focus adjustment
5) draw a low power image. Rotate the objectives do that the high power objective(eg.40) is in line with the stage
6) bring the slide back into focus using the fine focus adjustment. If you don’t succeed, go back to low power and re-focus and start again

40
Q

Name the risks of doing the analysing biological specimens using microscopes practicals

A

-care must be taken when looking down the microscope- illumination is not too bright as eye damage could be caused
-using some microscope stains as some are harmful
-handling coverslips and microscope slides-broken glass could cut the skin

41
Q

Give the method to measure cell size

A

1) place a stage micrometer on the stage of the microscope
2) line up one of the division on the eyepiece graticule with a fixed point on the stage micrometer
3) count the number of divisions on the eyepiece graticule that correspond with a set measurement on the stage micrometer.
4) calculate the distance in micrometers of one division on the eyepiece graticule