Biology
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Answer pre-lab questions.
 Think, pair, share
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Location of Safety Equipment including
Emergency Exits
Safety Questions
Location of Lab Equipment
Identification of Lab Equipment
Analysis and Critical Thinking - HW
1.
Always follow the teacher’s directions. Never perform activities that
are not authorized by your teacher.
1.
Read ALL directions for an investigation several times. Follow the
directions exactly as they are written. If you are in doubt about any
part of the investigation, ask your teacher for assistance.
2.
Keep your laboratory area clean and free of unnecessary books,
papers, and equipment.
3.
Be serious and alert when working in the laboratory. Never “horse
around” in the laboratory.
4.
Never eat or taste anything in the laboratory unless directed to do so.
This includes food, drinks, and gum, as well as chemicals. Wash your
hands before and after every investigation.
6.
Report all accidents, no matter how minor, to your teacher
immediately.
7.
Point a test tube or bottle that is being heated away from you and
others. Chemicals can splash or boil out of a heated test tube.
8.
Never heat a liquid in a closed container. The expanding gases
produced may blow the container apart, injuring you or others.
9.
Never use broken or chipped glassware. If glassware breaks, notify
your teacher and dispose of the glassware in the proper trash
container.
10.
When an investigation is completed, clean up your work area and
return all equipment to its proper place.
1
3
2
4
5
Petri Dishes
Erlenmeyer
Flask
6
Slides
Forceps
7
Slide Covers
8
Graduate
d Cylinder
Dropper
11
10
Test
Tube
9
Thermometer
Funnel
Beakers
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List two of the top ten Science Safety Rules
that students should follow in the science
laboratory.
Eyepiece or Ocular Lens – contains a
magnifying lens usually 10x magnification
B. Arm – connects to base and supports
the body tube; when carrying
microscope one hand must hold the arm
C. Coarse focus – raises and lowers the
stage or body tube for focusing image;
use on LOW power objective only
D. Fine focus – slightly moves the stage or
body tube to sharpen (adjust) the image;
use on Medium or High power objective
A.
E.
F.
G.
H.
I.
Base – supports the microscope
Light source/Illuminator/Projection
Lens – produces light or reflects light
up toward the eyepiece (may be a
mirror)
Diaphragm – regulates the amount of
light passing up toward the eyepiece.
Stage – supports the slide being
observed
Stage Clips – holds slide firmly in
place
J.
K.
L.
M.
N.
High Power Objective Lens – focuses
minute details on slide; provides a
magnification of 40x
Medium Power Objective Lens – after
finding image on low power, use to sharpen
image; provides a magnification of 10x
Revolving Nosepiece – holds the objectives
and can be rotated to change magnification
Body Tube – maintains the proper distance
between the eyepiece and the objectives
Low Power Objective Lens – 1st objective
used for focusing; provides a magnification
of 4x (10x if no Medium power obj lens)
1.
Always carry the microscope in an upright
position with two hands. One hand should
support the base and the other should be on the
on the arm. Do NOT swing the microscope
CORRECT!!!
INCORRECT!!!
Never touch lens with your fingers! Oil produced
from your body smudges the glass.
3. Use lens paper and lens cleaning solution to clean
the lenses on the microscope.
2.
 Paper towel will scratch the lenses.
 Use a soft cloth to clean other parts of the microscope.
3.
4.
Always set your microscope on a clean, flat
surface.
When finished with the microscope, always
remove slides from the stage.
 Rotate the nosepiece to the lowest power.
 Clean stage with lens paper.
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Carry microscope with one hand under base and
grasp arm with other hand
Gently place the microscope on the table with arm
facing you.
Raise body tube by turning the course adjustment
knob until the objective lens is about 2 cm above
the opening of the stage.
Rotate the nosepiece so that the low power
objective is directly in line with the body tube.
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Look through the eyepiece and switch on the
lamp or adjust mirror to that a circle of light can
be seen.
 Moving the diaphragm lever permits a greater or
smaller amount of light to come through the opening of
the stage.
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Place prepared slide on the stage so that the
specimen is over the center of the opening.
 Use stage clips to hold slide in place.
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Look at the microscope from the side. Carefully turn
the coarse adjustment knob to raise the stage until the
low power objective almost touches the slide or until
the body tube can no longer be moved.
 Do NOT allow the objective to touch the slide
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Look through the eyepiece and observe the specimen.
If the field of view is out of focus, use the course
adjustment knob to LOWER the stage while looking
through the eyepiece until the object comes into focus.
 You are moving the slide AWAY from the objective lens
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Focus the image as best you can with coarse
adjustment knob. Then use fine adjustment knob to
focus the image more sharply.
Adjust diaphragm lever to allow the right amount of
light to enter.
To change the magnification, rotate the nosepiece
until the desired objective is in line with the body
tube. ONLY use FINE adjustment knob with
medium and high power lens
 FIRST use medium power lens to sharpen image.
 SECOND use high power lens to focus minute details.
Three types of microscopes
Compound Light Microscope
Transmission Electron Microscope (TEM)
Scanning Electron Microscope (SEM)
•
•
Magnification – increase of an object’s
apparent size
• Total magnification: mag. of eyepiece x mag. of
objective lens
 Ex: (10X) x (4X) = 40X
Resolution (resolving power) – the distance
needed to distinguish 2 points as separate
Resolving Power
The human eye is capable of distinguishing objects down to a fraction
of a mm. With the use of light and electron microscopes it is possible
to see down to an angstrom and study everything from different cells
and bacteria to single molecules or even atoms.
•
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Specimen is enlarged as light passes through set
of glass lenses
Can be used to view living specimens
Resolving power is limited to the physical
character of light – up to 200 nm
Magnification up to 2000x
 beyond ~2000x the image becomes
blurry
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•
•
Cannot be used to view living specimens
Transmits a beam of electrons focused by a
set of magnetic lenses through a specimen
Creates a flat image
Magnification – up to 5,000,000x
Resolution – up to 0.2nm
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Cannot be used to view living specimens
A narrow beam of electrons is pass over the
surface of the specimen, which is coated with
a thin layer of metal, producing a 3D image
Magnification up to 500,000X
Resolution – up to 10 nm
Microscope
Compound
Light
Scanning
Electron
(SEM)
Function
 Uses visible
light to
illuminate a
thin section of
sample
Max
Magnification
 Approx. 2000x
 School light
microscopes
40-400x
 Lets you look at  Approx
the surfaces of
500,000x
objects at high
resolution
 Lets you look at  Approx.
a very thin
5,000,000x
Transmission cross-section of
an object (such
Electron
as a cell)
(TEM)
Best for
 Looking at some living
things (ex – a single cell
layer
 Looking at cells and tissues
(preparation steps are less
critical than for electron
microscopy)
 Getting an overvies of a
sample
 Looking at the surfaces of
objects
 Looking at objects in 3D
Disadvantages
 Low resolution compared
to the electron microscope
 Resolution often not as
high as the transmission
electron microscope
 Can’t be used to look at
living things (samples
need to be dried and
coated in metal before
visualizing)
 Costly to run
 Looking at internal structure  Can’t be used to look at
of objects
living things (samples
need to be prepared
 Looking at objects at very
extensively before
high resolution
visualizing
 Looking at relationships
 Costly to run
between stuctures at high
resolution
http://www.sciencelearn.org.nz/Contexts/Exploring-with-Microscopes/Sci-Media/Interactives/Which-microscope
Transmission electron microscope image of a human
leukocyte (also known as a white blood cell), showing the
Golgi apparatus, which is a structure involved in protein
transport in the cytoplasm
of the cell.
http://www.sciencelearn.org.nz/Contexts/Exploring-with-Microscopes
A head louse clasping a human hair. The image was taken using an SEM at
110x magnification. At low magnifications like this, SEM generates threedimensional images that are in focus throughout the depth of the sample.
http://www.sciencelearn.org.nz/Contexts/Exploring-with-Microscopes
http://remf.dartmouth.edu/imagesindex.html