Sec. 4- Tools and Procedures Metric system-decimal system of measurement whose units are based on...
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Transcript of Sec. 4- Tools and Procedures Metric system-decimal system of measurement whose units are based on...
Sec. 4- Tools and Procedures
• Metric system-decimal system of measurement whose units are based on certain physical standards– Scaled on multiples of ten
Length Mass Volume Temperature
1 m= 100 cm 1 kg= 1000 g 1 L= 1000 mL 0 deg Cel= freezing pt of water
1 m= 1000 mm 1 g= 1000 mg 1 L= 1000 cm3 100 deg C= boiling pt of water
100 m= 1 km 1000 kg= 1 metric ton
Microscope• What is the most widely used tool in
biology?– Microscope
• What is a microscope used for?– View object too small to be seen with the
naked eye.• How does a microscope enlarge an object?
– By magnification with lenses• What is magnification?
– It is a microscope’s power to increase an object’s apparent size.
Light Microscope• This microscope uses a beam of light (sun or light
bulb) to pass through a series of lenses to produce an enlarged image.– Can use it on dead or alive organisms– Can magnify the object a 1000 times
• 2 lenses used in the light microscope– 1. Objective lens – closest to the specimen
being viewed. Usually 3 objectives.– 2. Eyepiece (ocular lens) – closest to the eye
• How is magnification figured in a microscope?– Eyepiece magnification X Objective
magnification
Electron Microscope• An electron microscope works by beam of
electrons being shot onto the specimen, which enlarges the object as an image.
• You cannot observe living organisms with this microscope.
• 2 main types of electron microscopes
– 1. Transmission electron microscope (TEM) – uses an extremely thin sliced specimen.
• It magnifies all the way up to 2 million times.
2. Scanning electron microscope (SEM) – scans the surface of an object through the use of an electron beam. The object is prepared by covering the object with a thin layer of gold and platinum spray. The image produce is a 3-D image.
• It magnifies the image 50,000 to 100,000 times.
• Copies can be printed off from the image.
• It costs between $30,000 – $80,000
Microscope Parts• 1. Field- area seen through the
eyepiece.• 2. Eyepiece or Ocular lens• 3. Course focus- used first when
focusing• 4. Fine focus- to fine focus the object.• 5. Low power- field is larges and least magnified.• 6. High power- field is smallest and
most magnified.
• 7. Diaphragm- regulates amount of light allowed in.
• 8. Objective- adjustable lenses.
• 9. Resolution- the clarity of the field.
• 10. Micron- microscope’s unit of measurement.
• Light Microscope is limited to about 1,000 X.