Sec. 4- Tools and Procedures Metric system-decimal system of measurement whose units are based on certain physical standards –Scaled on multiples of ten LengthMassVolumeTemperature 1 m= 100 cm1 kg= 1000 g1 L= 1000 mL0 deg Cel= freezing pt of water 1 m= 1000 mm1 g= 1000 mg1 L= 1000 cm3100 deg C= boiling pt of water 100 m= 1 km1000 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.