Midterm Study Guide

Midterm Study Guide - Vandan Desai Section: 201 Biology 100...

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Vandan Desai Section: 201 1 f g m k i j e d h b c a l Biology 100 Lab—Midterm Study Guide I. Lab #1: Cells and Microscopes A. Learn names and functions (what they do) of parts of microscope i. Microscopes —designed to make objects visible that are too difficult or too small to see with unaided eye a light source b condenser …used to focus or concentrate light on the specimen c iris diaphragm …used to adjust the amount of light on specimen d objectives …contain lens system (4X—scanning; 10X—intermediate 40X—high-power; longest) e revolving nosepiece …holds objectives f ocular or eyepiece …typically 10X; binocular = 2 eye pieces g body tube h stage …this is where specimen sits i course adjustment knob …provides course adjustments of focus j fine adjustment knob …provides fine adjustments of focus k stage clips …holds specimen in place l base …acts as a stand and houses the lamp m arm …supports stage and condenser lens n head …supports the two sets of magnifying lenses Figure 1: Compound Microscope Components B. Learn the terminology used to describe the features of microscopes i. Parfocal lens —little reinforcing required when moving from one lens to another ii. Interpupillary distance —distance between the eyepieces iii. Field of view —amount of specimen that is visible in the scope; circle of light visible iv. Working distance —the distance between the objective tip and the sample slide v. “Depth of field” —the thickness of specimen that is simultaneously in focus 1. Large = all threads focused at the same time (4X) 2. Small/Narrow = only one/part focused (40X, 10X) C. Learn how the different types of microscopes work i. Compound light microscope: 1. Uses two sets of lenses (ocular and objective) to magnify the object 2. Illumination provided by a light source on the base of the microscope 3. Coverslip must always be used to… a) Flatten the preparation, b) Keep the preparation from drying out, and c) Protect the objective lens ii. Stereoscopic microscope (dissecting microscope): 1. Greater depth of field (objects seen in 3D) 2. Light source directed down/up an object—permits viewing of thick objects a. Light directed down on the object—reflected/incident light n
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Vandan Desai Section: 201 2 b. Light passing through the object—transmitted light 3. Specimen can be viewed without a coverslip iii. Electron microscope: 1. Electrons as illumination 2. Image magnified by electromagnets 3. Uses objective, condenser, and is always binocular 4. Have greater resolving power b/c uses electrons (have shorter wavelength) instead of light to illuminate the specimen D. Learn when it’s appropriate to use each type of microscope / Know the limits (relative size and type of specimen) of each type of microscope i. Compound light microscope: 1. Magnification (40X – 1000X); 2. Used with objects that range in size from 100nm – 2mm ii. Stereoscopic microscope: 1. Relatively low magnification (7X – 30X) 2. For viewing large/thick objects iii. Electron microscope: 1.
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Midterm Study Guide - Vandan Desai Section: 201 Biology 100...

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