Microscopes

Question 1

Optical microscopes

Answer 1

-Uses light
-Light has relatively long wave length so poor resolution
-Cant see ribomes

Question 2

electron microscopes

Answer 2

-Use a beam of electrons instead of light
-Electrons have a shorter wavelength so better resolution
-Giving a more detail;image

Question 3

Transmission electron microscopes

Answer 3

An electron beam passes through a thin section of a specimen
-Parts absorb electrons and appear darker
-Image produced on a screen
+Give high resolution
+Allows internal structures within cells to be seen e.g. ribosome
-Can not observe live specimens
-Cant obverse colour

Question 4

Scanning electron microscopes

Answer 4

Scan beam of electrons accross specimens
-Bean bounces off the surface of a specimen, and electrons are detected forming an image
+Allow 3D image of specimen to be observed
+Can be used on thick specimens
-Lower resolution than TEM
-Can’t be used to observe live specimens

Question 5

How did scientists previously distinguish between artefacts and cell organelles

Answer 5

-Repeatedly prepared specimens in different ways using different techniques
-If they saw an object in a specimen prepared using one preparation technique but not another. The object was more likely to be an artefact than an organelle.

Question 6

Resolution

Answer 6

The ability to distinguish between 2 separate points

Question 7

Magnification

Answer 7

How many times bigger the image of the specimen appears compared to the actual size of the specimen

Question 8

Compare optical and electron microscopes

Answer 8

1. Optical shines light through a specimen, electron fires a beam of electrons
2. With optical specimens can be living or dead, electron the specimens are dead
3. Optical have low resolution due to long wavelength of light, electrons have shorter wavelength so higher resolution
4. Optical have a simple sample preparation, electron have a complicated sample preparation