Introduction to Cells
Topic 2: Investigating Cells
Standard Grade Biology
Magnification
Cells can be seen more clearly using
microscopes
magnify
Microscopes _________________________
the cells
Microscopes may have two or
objective lenses
three__________________________________________
and one
eyepiece lens
___________________________________________.
Calculating Magnification
To work out Total Magnification use the
following formula
TOTAL
MAGNIFICATION
=
magnification of
eyepiece lens
x
magnification of
objective lens
Since microscopes magnify cells we
have a new unit of measurement.
These new units are called
microns
_________________________.
1mm
1
1000
=
=
1000 µm
1 µm
Measuring Cell Size
We can use microscopes to estimate the
size of cells we are looking at
e.g. if we know the diameter of the field of
our field of view we can then estimate the
size of the cells
a)if the field of view = 1mm
Field of view
Onion cell
then onion cells are
1mm (1000 µm)
0.5
______________ mm
500 microns
or ______________(µm)
in length
b)if the field of view = 0.5mm or 500µm
then these cheek cells would be
500
5
100 µm in length
mm or ______________
0.5 mm (500 µm)
Human cheek
cell
Magnification
mm
Field of View
Microns (µm)
X40
4
4000
X150
1
1000
X400
0.5
500
Staining Cells
Animal and plant cells can be
stained
_________________________
so that the
structures within cells
____________________________________
seen more clearly
can be______________________________
_________________________
stains the
Iodine
nucleus
_________________________
of onion
cells and also its
cell wall
_________________________.
Methyl Blue
_________________________ is
used to stain the
nucleus
_________________________ of
human cheek cells
__________________________.
Acetic orcein
_________________________ is used to
chromosomes
stain the _________________________
present in the nucleus of cells which are
about to divide.
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