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BI Lab 4
Term | Definition |
---|---|
all organisms are composed of one or more cells, the cell is the basic living unit of organization, and all cells arise from pre-existing cells | cell theory |
compound light microscope | contains two or more lenses that collect and focus light passing through a transparent specimen producing a magnified image |
magnification | the degree to which the image of a specimen is enlarged |
resolution | resolving power; how well specimen detail is preserved during the magnifying process |
contrast | the ability to see specimen detail against its background |
field of view | the circle of light one sees in the microscope when looking through the eyepiece |
decreases, meaning a smaller area of the slide is visible | as magnification increases, the field of view _______________ |
working distance | the space between the slide and the objective |
depth of field | vertical depth of an image that remains in sharp focus under a particular magnification |
ocular or eyepiece | located in the upper end of the body tube. the magnification power is 10x |
arm | functions as the handle of the microscope |
objective lenses | attached to the revolving nosepiece. housed in one end of several steel tubes that are threaded into the revolving nosepiece |
stage | large platform just below the revolving nosepiece |
mechanical stage | apparatus located on the stage that holds a specimen mounted on a glass slide in place suspended over the stage opening |
mechanical stage knobs | one moves the slide forward and back and the other moves the slide from side to side |
coarse adjustment knob | used to move the stage up and down, so that you can bring the specimen into focus (only when using 4x) |
fine adjustment knob | use when looking at objects using the low power objective (10x) and the high dry power objective (40x). used to bring the specimen into sharp focus |
condenser | located between the diaphragm and the stage; converges light rays from the light source so that they pass through the specimen on the slide and into the objective lens |
condenser adjustment knob | located underneath the stage on the left side just behind the condenser; adjusts the condenser for proper positioning to converge light rays passing through the specimen |
iris diaphragm | lever located below the stage that regulates the amount of light passing through a specimen, thus improving the contrast of the image |
illuminator | located below the condenser; contains the light source - a light bulb |
base | lowermost part of the microscope and is in contact with the table |
light switch | back of the microscope next to the electric cord mount |
rheostat | varies the intensity of light coming from the illuminator; located on the top of the base |
total magnification | multiply the power of the eyepiece times the power of the objective lens being used |
permanent slide | purchased from a biological supply house and is sealed with a permanent glue |
temporary wet mount | prepared in the lab usually using water as the suspension medium |
parfocal | the ability of the microscope to remain in focus when switching from one objective lens to the next highest power |
chloroplasts | function in photosynthesis and are necessary for plant life |
cell wall | important for structural support and is not found in animal cells |
plasma membrane | located inside the cell wall, is not visible bc it is pressed tightly against the cell wall and bc it is beyond the resolving power of the light microscope |
cytoplasmic streaming | positions the chloroplasts toward light and distributes heat throughout the cell |
central vacuole | provide hydrostatic pressure or turgor within individual cells |
turgor | hydrostatic pressure |
nucleus | control center of the cell; houses the DNA |
plasma membrane | surrounds the cell and regulates what moves into and out of the cell |
cytoplasm | the jelly-like material found between the cell's nucleus and plasma membrane |
organelles | structures which perform specific cell functions |
stereomicroscope | has two eyepieces that give a three-dimensional view of the specimen |