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micro lab test 1
Stack #23741
| question | answer |
|---|---|
| How much larger will specimen appear with the oil immersion objective | 2.5 x larger |
| What lens is required to clearly see the great majority of bacteria | Oil objective(1000x) |
| What controls the amount of light passing thru a specimen | iris diaphragm |
| Is field of small or larger at higher magnification | smaller |
| What lens is good to use for scanning the slide to look for specimens | 40x |
| What is the purpose of the oil immersion objective | to resolve objects not easily resolved and provide greater detail |
| As magnification increas what happens to depth of focus | decreases |
| What is order of objectives | red,yellow,blue,white,red |
| What are the three types of bacteral shapes | bacillus, coccus, spirillium |
| What are cells | basic structural and functional units of living organisms |
| What is the size of a typical cell | 10-20 micrometers |
| What is the typical size of a bacterial cell | 0.5-6 micrometer depending on species |
| What do you use to clean lens of microscope | lens paper |
| What should position should scanning objective be in before putting microscope away | 40x |
| The coarse focus knob should only be used with ________ | scanning and low power objectives |
| The fine focus knob is used to ________ | bring the specimen into sharp focus |
| What is the scanning lens | 4x |
| What is the low power lens | 10x |
| What is the high power lens | 40x |
| What is the oil immersion lens | 100x |
| What is the amount of light necessary to get the best image | the least possible |
| What 2 factors does resolution depend on | wavelength and numeric aperture |
| What practical value does the hang drop method have | bacteira can be seen at greater depth |
| What practical value does the wet mount method have | fast way to observe bacteria with greater magnification |
| Whay are microorganisms hard to see in wet mount preparations | They ar eunstained and have no contrast |
| What is the shape of bacillus | rod shaped |
| What is the shape of cocci | round |
| Van Leeuwenhoek | first to observe microbes in suspension |
| Brightfield micrscopy | objects are dark and field is light |
| darkfield microscopy | Objects are light and field is dark |
| What is an innoculating loop | A Nichrome wire held with an insulated handle |
| Before and after it is used the innoculating loop is sterilized by? | flaming until red hot |
| Staining procedures that use only one stain are? | simple stains |
| The ion that is colored in stains is called a | chromophore |
| If the chromophore is a positive ion it is what kind of stain | basic stain |
| If the stain has a negative ion it is what kind of stain | acidic stain |
| A simple stain that stains the bacteria is called a | direct stain |
| A simple stain that stains the background but leaves bacteria unstained is a | negative stain |
| Simple stains are used to | determine the morphology size and arragement |
| A smear is made by | spreading a bacterial suspension on a clean slide and allowing it to air dry |
| How is bacteria heat fixed | after it is air dried you pass it thru the flame several times |
| How can bacteria be chemically fixed | cover the smear with 95% methyl alcohol for 1 minute |
| In negative staining why are bacteria not stained | because of ionic repulsion bacteria and stain both have negative charges |
| Are bacteria heat fixed in a negative stain | No |
| The negative stain is useful for determining | cell morphology or size |
| What kind of stain is the gram stain | differential stain |
| What is the mordant in a gram stain | grams iodine |
| What is the counter stain in a gram stain | safranin |
| Bacteria that decolorize easily are classified as | gram negative |
| What color are all bacteria after primary stain is applied | purple |
| Bacteria that decolorize slowly and retain primary stain are called | gram positive |
| In gram negative cells what does the decolorizing agent dissolve | outer lipopolysaccharide layer and the cv-i washes through the layer of petidoglycan |
| When is the gram stain most consistent | when done on young cultures |
| What are the steps for a gram stain | crystal violet, grams iodine, ethyl alcohol, safranin |
| Endospores are formed mainly by | Clostridium and bacillus |
| Endospores are called | resting bodies |
| When are endospores formed | When essential nutrients or water are not available |
| Once an endospore forms in a cell what happens to the cell | It disentagrates |
| Endospores are impermeable to most stains so how are they stained | Heat is applied to drive stain into cell |
| What are the stains used for endospores | malachite green and safranin |
Created by:
nurse d
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