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37 Cards in this Set
- Front
- Back
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What is science? |
A way of investigating how the world works. |
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Name the steps of the scientific method. |
Observations, Hypothesis, Experimentation, Revised-Hypothesis, Theory, Predictions |
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Which objective lens has the largest depth of field? |
4x |
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What should you do when putting away the microscope? |
Turn the lamp down to 1, turn the light switch off, and turn the nosepiece to the 4x objective lens. |
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When examining a sample under a microscope, what objective lens should you start with? |
4x |
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Oil immersion involves filling the space between nosepiece and sample because... |
Oil has the same optical properties as glass. |
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What is the purpose of the microscope stage? |
To provide a secure place for the specimen slide to rest during observation. |
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When using a high magnification lens, only use this to focus the sample: |
Fine focus knob |
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What is resolution? |
The smallest distance between two points that one's microscope can allow a viewer to distinguish between two distinct points. |
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The highest effective magnification that can be achieved with a light microscope is about: |
1000-fold |
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All bacteria can be divided into what two groups? |
Gram-Positive and Gram-Negative |
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The presence of lactose-fermenting, gram-negative bacteria in water is a good indicator of what? |
Human fecal contamination in the sample. |
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A differential bacterial medium serves what purpose? |
It allows one to distinguish between different groups of bacteria. |
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Eosin, Methylene Blue (EMB) agar is a bacterial media with what properties? |
It is both differential and selective. |
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What temperature is best for incubation of bacterial plates? Why not human body temperature? |
25* Celsius - Human body temperature (37* Celsius) is too warm a temperature for many environmental bacteria. |
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What is the purpose of a plankton net? |
To concentrate eukaryotic microbes in water samples. |
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When creating a spread plate, what must be done with the bent glass rod before using it to spread the bacterial sample? |
It must be dipped in ethanol and passed through a flame for sterilization. |
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What is the purpose of adding methyl cellulose to a concentrated water sample? |
The methyl cellulose increases the sample fluid's viscosity and slows down the microorganisms found therein. |
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What contribution did Robert Koch make to biology? What is its significance? |
Koch developed solid media, allowing for the discovery of individual species of bacteria. |
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Why are Petri dishes helpful for growing bacteria? |
They provide a sterile environment while allowing gas exchange. |
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What are the characteristics that can be used to distinguish bacterial colonies? |
Form, Elevation, Margin, Pigmentation |
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What is the difference between a simple stain and a differential stain? |
A simple stain uses only one dye, while a differential uses multiple. |
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What are the two most common bacterial cellular morphologies? |
Coccus and bacillus |
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What does CFU stand for? |
Colony Forming Units |
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Why do lactose fermenters appear black or purple on an EMB plate? |
Lactose fermentation produces acidic waste products that lower the ambient pH. |
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When streaking for isolation, what must be done to the wire loop? |
It must be passed through a flame for sterilization. |
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What should not be done when staining bacteria? |
Blowing on bacteria to dry the slide, rubbing the slide dry, using too much bacterial sample, over-fixing the sample in flame. |
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What should be done after using the oil-immersion lens? |
Move the 4x objective into place: not the 40x. |
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Can bacteria grow in normal fresh water? |
Yes. |
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Name a modern molecular biology technique that can be used to identify bacteria. |
DNA sequencing. |
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Define polymorphisms. |
Differences in DNA sequences between individuals. |
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Which gene can be used to identify bacterial species? |
16S ribosomal RNA gene. |
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After Gram staining, why do G+ bacteria appear purple while G- bacteria appear pink? |
G+ bacteria have a thick peptidoglycan cell well that absorbs the violet stain. |
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What are the steps in a polymerase chain reaction experiment? |
Denaturation, Annealing, Extension |
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Gram staining allows for differentiation between what two bacterial subsets?
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Gram Positive and Gram Negative bacteria. |
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Gram-Positive and Gram-Negative bacteria are generally stained what two colors? |
Purple for G+, red for G-. |
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What reagents are used in differential Gram staining? |
Crystal violet, Iodine, Decolorizer, and Safranin. |
