OPTICAL MICROSCOPES

Question 1

how to prepare a temporary mount

Answer 1

1. pipette a drop of water onto the slide
2. use tweezers to place a thin layer of cells / thin section of specimen onto the slide
3. add a drop of stain
4. lower a coverslip over the specimen using a mounted needle. the cover slip protects the specimen making sure no air bubbles get in

Question 2

about light microscopes

Answer 2

light passes through specimen and is focused through glass lenses, which project a magnified image
max resolution of 0.2 micrometers
cant view smaller organelles
specimen must be thin so light can pass through
stains e.g. KI make certain structures more visible

Question 3

advantages of light microscopes

Answer 3

can view live specimens
can show colour
less time consuming to prepare slides

Question 4

disadvantages of light microscope

Answer 4

lower resolution compared to elec
lower magnification compared to elec
cant view smaller organelles in detail

Question 5

what is an eyepiece graticule

Answer 5

scale in the eyepiece typically 10mm long and is divided into 100 sub sections

Question 6

what is a stage micrometer

Answer 6

a slide with a scale etched on, 10mm long with 1mm sub divisions and the smallest subdivisions of 0.1mm