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Unformatted text preview: Chapter 1- Microscopy Objective- Produces a magnified image of the object observed. Ocular (Eyepiece)- Magnifies the image produced by the objective. Compound microscope- Contains a single compound lens system with magnifications of 40X, 100X and 400X. Illumination occurs below the stage. Objects observed must be transparent at varying degrees to see contrast. Dark objects absorb more light. Dissecting microscope- Has two complete compound lens systems and magnifies from 8X to 50X. Illumination occurs above the stage. The objective collects light reflected by the object to form an image. Light microscopy- Uses glass lenses and visible radiation. The image observed is produced by the light reflected from or transmitted through the object. Resolving power limited by wavelength of radiation used (longer wavelengths). Electron microscopy- Uses electromagnetic or electrostatic lenses and fast-moving electrons. Resolving power increased by shorter wavelengths used. Limited by a narrow angular aperture. Substage condenser- A lens that focuses light on the object lying on the stage. Resolving power- The empirical estimate of optical resolution. Depends on the wavelength of radiation, refractive index of the medium, and the acceptance angle of the objective lens. Is found by 0.6 / n sin or 0.6 / numerical aperture. -Improves with decreasing wavelength-Improves with increasing numerical aperture-Improves with increasing refractive index-Improves with increasing acceptance angle Minimal resolvable distance- Measures the resolving power, and is the minimal distance between two point objects that can be distinguished in their images formed by the lens. Decreases as resolution and resolving power improves. Acceptance angle- The angle subtended by the apex of the cone. Numerical aperture- n sin . Total magnification- The product of the magnifying powers of the objective and ocular. Transmission electron microscopy- Depends on transmission of electrons through the object. Requires very thin sections. Metal ion staining is used to create contrast. Very good magnification and resolution. Scanning electron microscopy- Uses electron gun, does not use lenses. Electrons striking object causes secondary electrons to emit from object. Metal coating results in enhanced scattering. Specimen thickness not critical. Very good depth of field and 3D view of object. Chapter 2- Biology as a Science The Scientific Method 1. Observation and hypothesis formation 2. Making predictions and testing hypotheses 3. Analysis and interpretation Research (working) hypothesis- Tentative explanation for the new observation. Inductive logic- Involves making a general statement that summarizes specific observations and attempts to make them consistent with an explanatory system....
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This note was uploaded on 04/07/2008 for the course BIO G 103 taught by Professor Chen,k.c during the Fall '06 term at Cornell University (Engineering School).
- Fall '06