1: Electron Microscopes and Ultrastructure Flashcards Preview

IB Biology SL > 1: Electron Microscopes and Ultrastructure > Flashcards

Flashcards in 1: Electron Microscopes and Ultrastructure Deck (15):
1

Define resolution.

1. is the ability of the microscope to show two close objects separately in the image

2

How do you know when the resolution of the microscope has been exceeded?

1. the point above which the image can no longer be focused sharply

3

What does resolution depend on?

1. the wavelength of the rays used to form the image
2. the shorter the wavelength, the higher the resolution

4

What has a shorter wavelength: electrons or light? What does this mean for microscopes?

1. electrons
2. electron microscopes have a higher resolution than light microscopes
3. they can therefore produce a sharper image at much higher magnifications

5

What is the resolution in a light microscope and electron microscope, respectively?

1. light: 0.25 um
2. electron: 0.25 nm

6

What is the maximum magnification in a light microscope and electron microscope, respectively?

1. light: x500
2. electron: x500,000

7

Name two types of electron microscope and their uses.

1. Transmission electron microscope (TEM): used to view ultra-thin sections
2. Scanning electron microscope (SEM): produce an image of the surfaces of structures

8

Draw and label a scanning electron microscope (SEM). (p5)

1. voltage feed
2. electron gun
3. vacuum
4. electron beam
5. condenser
6. specimen
7. objective lens
8. intermediate lens
9. projector lens
10. viewing port
11. fluorescent screen

9

There is an important trend in science related to technology and discovery. What is it? Give an example.

1. improvements in technology or apparatus lead to developments in scientific research
2. invention of the electron microscope led to a much greater understanding of the structure of cells known as the ultrastructure

10

You need to be able to recognise different ultracellular components of a cell, and label a micrograph. This needs exam question practice and knowledge of the ultrastructure of eukaryotic cells (next deck).

They may also ask you to "deduce the function of the specialised cell" e.g. chloroplasts + large vacuole so function = photosynthesis"

11

What do chloroplasts do?

1. carry out photosynthesis

12

What does the cell wall do?

1. supports and protects the cell

13

What does the plasma membrane do?

1. controls entry and exit of substances

14

What do the (free) ribosomes do?

1. synthesize cytoplasmic proteins

15

What does the nuclear membrane do?

1. protects the chromosomes

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