Chapter 1 Sect 1- 4

Reference:Modern Biology

Pgs. 21 - 24

•Scientific tools and techniques enable Biologists to probe deeper into the secretes of life

BIG IDEA

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.

TOOLS OF THE TRADE: 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 lenseso 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

LIGHT 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

ELECTRON MICROSCOPES

Body Tube

Ocular Lens

Revolving Nosepiece

Objective lens

Objective lens

Objective lens

Stage Clips

Diaphragm

Light source

Arm

Stage

Course Focus / Adjustment

Fine Focus / Adjustment

Base

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)

Tools of the trade

BASE UNIT MEASURES

Meter Length

Liter Volume

Gram Mass

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

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 TRADEPREFIX …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

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

millimetersSo..• 1 centimeter = 10 millimeters

1 10 100 1000.10.01.001

Kilo- Hecto- Deka-BASE UNITMeterGramliter

Deci- Centi- Milli-

Tools of the trade

US Conversions within theMetric System

TOOLS OF THE TRADE

Mass vs. Weight(Not the same!)

Mass-How much matter (particles) you are made of.Weight-How much gravity pulls on you.

A QUICK SIDE NOTE…