Microbiology LAB Exam 1 with Complete Solutions

Microbiology LAB Exam 1 with Complete Solutions Microscope- The Condenser focuses the light ging into the objective lens Microscope- The Iris Diaphragm adjusts the amount of light going into the objective lens Microscope- Nosepiece holds the objective lenses and rotates to change from one objective to another Microscope- Coarse Objective Knob moves the stage larger distances to help get the object in focus Microscope- Fine Adjustment Knob moves the stage smaler increments to help get the object in better focus Microscope- Objective Lens magnifies the object. It is located near the object. Microscope- Occular Lens magnifies the image of the object from the objective lens. It is located near the eye. Steps in using the microscope 1) scanner power in place 2) place slide of specimen stage in place with stage clips 3) Using the course adjustment knob, raise the stage all the way up and then down slowly until you can see image of specimen 4) Readjust with fine adjustment knob Describe the purpose of the oil immersion lens Used when oil is added to the slide. Oil must touch the object and objective lens to that the light does not refract futher Parfocal Parfocal microscopes are able to move from one objective to the next and still be in focus due to the length of the objective lenses Resolution The ability to distinguish between two objects that are very close together. What is resolving power? The measurement of resolution What are two ways to increase resolving power? 1. By decreasing the wavelength of light (using a blue filter) 2. Increasing the numerical aperature What units are used to express resolving power? nm or nanometers What is better, smaller or larger resolving power? Smaller is better Light microscopes have a 200nm resolving power Electron microscopes have a .2nm resolving power What is chromatic aberration? The effect when many colors are seen toward the edge of the microscope field of vision (like a prisim) How are microscopes corrected for chromatic aberration? With a special achromatic lens (corrected for red and blue light) or by using a blue filter. The lab has blue filters in their microscopes which also increase resolution. Describe the process of making a wet-mount slide 1) Add the specimen to the slide 2) Touch the edge of the cover slip with one edge of drop of specimen. 3) Let the cover slip drop gradually to the slide, covering the drop of specimen. Describe the purpose of making a wet-mount slide To be able to see living organisms under the microscope in their natural state. What is the advantage of using a wet-mount slide?