This document consists of in depth notes written to equip you with all the knowledge required to achieve high results in Biology AS / A-level exams, written by a biology student who took her exams in summer of 2022. With these notes as my main source of revision, I achieved an A* and believe that i...
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↳ maximum image size
magnification 1500 ✗ actual
-_
=
size magnification
↳ resolution __
the smallest distance between two A M
distinguishable points 200hm
-_
.
magnification
↳
limited resolution also limits the .
anything magnified over 1500 ✗ would Deoutoffocust detail wouldn't be seen
'
.
differential staining DARKRED
↳ stain acetic orcein
__
a coloured chemical which binds to structures inoroncells DNA -
-
making them easier to see
cytoplasm → eosin
↳ increases contratasdifferent cellular
components within a cell lipids Sudan red
-
BLUE / BLACK
will take up different stains to different degrees
.
+ cell walls → iodine
↳
allows
todifferentiatebetweencellstypesofcells between tissues
cellulose
r
↳
also allows to differentiate between organelles within a cell . appears violet
under microscope)
electron microscopes
↳ transmission electron microscopes create black white 2D
a +
image
can upto 2. million times
magnify scanning electron microscopes can magnify
-
-
resolution of around 501pm 200,000
-
✗
resolution 210hm
-
eyepiece graticule :
↳ have an
arbitrary scale
used to measure objects seenina microscope at 40×1
-
.
eyepiece
graticule
graticule calibrated at each
magnification
↳ must be
with a
stage micrometer 1111 !:/
-
11111
"
111111111
stage micrometer mi¥8%eer
:
↳ nasa predetermined of 1mm
length
has 100 divisions on it 110µm
↳
. each)
at IOOX :
↳ to calibrate micrometer
, lineup the stage eyepiece graticule
+ .
↳
measure how
eyepiece 11111111111
long one division on the
ii. 1111111
:
graticule is
↳ divide the number of
stage micrometer intervals by
thenumberofeyepiecegraticulesitavers
togetthelengtnofone eyepiece graticule matnsy method
'
:
↳
use this measurement to measure objects if 45 1mm
eyepiece
__
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