What measurement system do most
Scientists use?
How are light microscopes and Electron
microscopes similar?
How are they different?
Ladder Method
1
2
KILO
1000
Units
HECTO
100
Units
3
DEKA
10
Units
DECI
0.1
Unit
Meters
Liters
Grams
How do you use the “ladder” method?
1st – Determine your starting point.
2nd – Count the “jumps” to your ending
point.
3rd – Move the decimal the same number
of jumps in the same direction.
CENTI
0.01
Unit
MILLI
0.001
Unit
4 km = _________ m
Starting Point
Ending Point
How many jumps does it take?
4. __. __. __. = 4000 m
1
2
3
Conversion Practice
Try these conversions using the ladder method.
1000 mg = _______ g
1 L = _______ mL
160 cm = _______ mm
14 km = _______ m
109 g = _______ kg
250 m = _______ km
Compare using <, >, or =.
56 cm
6m
7g
698 mg
Length
Length is the distance
between two points.
The SI base unit for
length is the meter.
We use rulers or meter
sticks to find the length of
objects.
Analyzing Biological Data
Scientists collect data to find out whether
certain factors change or remain the same.
Often, the simplest way to do that is
to record the data in a table and then
make a graph
Computers help scientists to gather, analyze, and
present large quantities of data.
Analyses of data are used to make predictions about
complex phenomena.
Microscopes
Microscopes are devices that produce magnified
images of structures that are too small to see with
the unaided eye.
Scientists today use
Two kinds of microscopes:
Light
Electron
A light microscope, also called an optical
microscope, is an instrument to observe small
objects using visible light and lenses.
Onion Peel
Stained animal
cheek cell
The electron microscope is a type of microscope
that uses a beam of electrons to create an
image of the specimen
Dust mite
House Fly
In order for a microscope to be useful, there
must be two important properties----
magnification and resolution
Magnification is the ability to make things
larger than they are
Resolution-the sharpness of an image
What’s my power?
To calculate the power of magnification, multiply
the power of the ocular lens by the power of the
objective.
6 steps of how to view a specimen under a
microscope:
1. Turn on the light
2. Lower the stage to minimum and click low
objective in
3. Slide over light hole
4. Focus slide/course adjustment
5. Click on high lens
6. Focus with fine adjustment
Compound light microscopes
• allow light to pass through
the specimen
• use two lenses to form
an image.
• Light microscopes make it
possible to study dead
organisms and their parts
• to observe some small
organisms and cells while
they are still alive.
Laboratory Techniques
• biologists place a single cell into a dish
• contains a nutrient solution.
The cell is able to reproduce so that a group of
cells, called a
cell culture,
develops from
the single
original cell.
Mosquito Cell Culture
Cell cultures
can be used to:
•test cell responses under controlled conditions
•study interactions between cells
•select specific cells for further study
Centrifuge
• Cells are broken into pieces in a special blender.
• The broken cell bits are added to a liquid and
placed in a tube.
• The tube is inserted into a centrifuge that spins,
causing the cell parts to separate, with the most
dense parts settling near the bottom of the
tube.
• A biologist can then remove the specific part
of the cell to be studied by selecting the
appropriate layer.