microscopes

Question 1

define magnification

Answer 1

how big an object appears to be compared to its actual size

Question 2

define resolution

Answer 2

the smallest distance that can be seen between two points

Question 3

what are the three types of microscope

Answer 3

laser scanning microscopes
optical microscopes
electron microscopes

Question 4

what are the advantages of an optical microscope

Answer 4

relatively cheap, easily portable, easy to use

Question 5

what are the disadvantages of an optical microscope

Answer 5

they can only magnify x1500-2000 so cant see smaller structure such as ribosomes

Question 6

describe laser scanning (confocal) microscopes

Answer 6

use laser light to scan an object point by point and display the image on a computer. they can be used on living cells and tissues and they show high resolution and high contrast.

Question 7

describe electron microscopes

Answer 7

use a beam of fast travelling electrons and so have a much greater resolution and can be used to give a clearer and more magnified image that light microscopes

Question 8

describe transmission electron microscopes

Answer 8

specimen has to be chemically fixed or stained. beam of electrons pass through the specimen. electrons form a 2D black ad white image

Question 9

describe scanning electron microscopes

Answer 9

electrons don’t go through specimen but secondary electrons bounce off the specimen’s surface and focused on a screen to give of a 3D image. computer can add false colour but is seen in black and white