microscopy

Question 1

magnification

Answer 1

how much bigger the image is than the specimen

Question 2

magnification formula

Answer 2

magnification = size of image/size of real object

Question 3

resolution

Answer 3

how detailed the image is
it is how well a microscope distinguishes between two points that are close together
if a microscope lens can’t separate two objects, then increasing the magnification won’t help

Question 4

optical microscopes

Answer 4

use light to form an image
have a maximum resolution of 0.2micrometres
cant see ribosomes, endoplasmic reticulum and lysosomes
maximum useful magnification is about x1500

Question 5

electron microscopes

Answer 5

use electrons to form an image
have a higher resolution that optical microscopes so give a more detailed image
maximum resolution of about 0.0002 micrometers
maximum useful magnification is about x1500000

Question 6

transmission electron microscopes

Answer 6

use electromagnets to focus a beam of electrons, which is then transmitted through the specimen

denser parts of the specimen absorb more electrons, which makes them look darker on the image you end up with

good as they give high resolution images, so you can see the internal structure of organelles like chloroplasts

can only be used on thin speciments

Question 7

scanning electron microscopes

Answer 7

scan a beam of electrons across the specimen - knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image

the images you end up with show the surface of the specimen and they can be 3D

good because they can be used on thick specimens but give a lower resolution image than TEMs