Chapter 1 Sect 1- 4
Reference:
Modern Biology
Pgs. 21 - 24
BIG IDEA
•Scientific tools and
techniques enable
Biologists to probe
deeper into the secretes
of life
TOOLS OF THE TRADE:
MICROSCOPES
One of the most widely used tools
in Biology is the Microscope.
WHAT DOES A MICROSCOPE DO?
• Enlarges an image as well as shows
detail.
• Magnification-the amount an object’s size
is increased
• Resolution-the power to show details
clearly
•
Microscopes vary in powers of magnification
and resolution.
LIGHT MICROSCOPES
*Compound Light Microscope
A Compound microscope has a series of
lenses to collect and focus the light
transmitted through the specimen
mounted on a glass slide
•Must be thinly sliced or very small
•Pair of lenses
o Ocular lens (eye piece)
o Objective lens (nose piece)
•Magnification determined by
multiplying power of both lenses
o Eyepiece 10X times Objective power
(10X, 20X, 40X…)
•Highest Maximum magnification is
around 1000X
•Can be used to study LIVE specimens
LIGHT MICROSCOPES
ELECTRON MICROSCOPES
*Transmission Electron Microscope (TEM)
•Uses a beam of electrons to produce an
enlarged image of very thinly sliced specimen
on screen or photographic plate
•Image focused by magnetic lenses
•200,000X magnification
•Cannot be used to view living specimens
ELECTRON MICROSCOPES
*Scanning Electron Microscope (SEM)
•3D image
•Specimens not sliced for viewing
•Surface sprayed with fine metal coating
•Also uses electron beam and fluorescent
screen or photographic plates
•100,000X magnification
•Cannot be used to view living specimens
Ocular Lens
Body Tube
Revolving Nosepiece
Arm
Objective lens
Objective lens
Stage
Objective lens
Stage Clips
Course Focus / Adjustment
Diaphragm
Fine Focus / Adjustment
Light source
Base
Tools of the trade
The International System of
Measurement, or SI is the one
system of measurements
scientists use.
ALSO KNOWN AS:
The Metric System
Tools of the trade
The Metric System
– Uses Base Units
• Describes what you are measuring.
»
»
»
»
»
Length-meter (m)
Volume-liter (L)
Mass-gram (g)
Temperature-Celsius (C)
Time-second (s)
BASE UNIT
MEASURES
Meter
Length
Liter
Volume
Gram
Mass
Tools of the trade
The Metric System
• Major advantages:
– It is a decimal system based on multiples or
fractions of 10’s
– Commonly used among all scientists
– Easy to convert between unit prefixes:
–
–
–
–
–
Kilo – 1000
Deci – 1/10th
Centi – 1/100th
Milli – 1/1,000th
Micro – 1/1,000,000th …of the base UNIT
TOOLS OF THE TRADE
PREFIX
…PLUS BASE UNIT
Kilo – 1/1000th
Kilo+gram =
Kilogram
Hecto – 1/100th
Hecto+liter =
hectoliter
Deka – 1/10th
Deka+gram =
dekagram
Deci - 10
Deci+liter =
deciliter
Centi - 100
Centi+meter =
centimeter
Milli - 1000
Milli+meter =
milliliter
In SI, prefixes are added to the
base unit to signify the value.
•Prefixes are multiples of 10…
•For example:
1 kilogram = 1000 grams
•1 centimeter = 1/100th of a
meter
•1 milliliter is 1/1000th of a
liter, or 1000 X smaller than a
liter
TOOLS OF THE TRADE
The SI System makes
conversions easier!
•1 mile=1760 yards=5280 feet= 63,360
inches – Ugh!!
•Because all of the unit relationships in
the metric system are based on multiples
of 10, it is easy to convert between prefix
units - just multiply or divide by 10!
•100,000 cm = 1000 meters = 1 kilometer
•1 kilometer = 1000 meters = 100,000 cm
Tools of the trade
For example:
• Centimeters are 10 times larger than
millimeters
So..
• 1 centimeter = 10 millimeters
Kilo-
Hecto-
.001
.01
Deka-
.10
BASE UNIT
Meter
Gram
liter
1
Deci-
10
Centi-
100
Milli-
1000
TOOLS OF THE TRADE
US Conversions within the
Metric
System
A QUICK SIDE NOTE…
Mass vs. Weight
(Not the same!)
Mass-How much matter (particles) you are
made of.
Weight-How much gravity pulls on you.