Microbial Growth Test Questions – Flashcards

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Buffer
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Used in media to neutralize acids
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Psychrophile
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The general term for organisms capable of growth at

0°C

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Thermophile
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Capable of growth at high temperatures;

optimum 50-60°C

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Extreme Halophile
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Adapted to high salt concentrations, which are required for growth
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Plasmolysis
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A phenomenon that occurs when bacteria are placed in high salt concentrations
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Psychrotrophs
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Term used in text for organisms that grow well at refrigerator temperatures; optimum growth is at temperatures of 20-30°C
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Capnophile
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Microbes that grow better at high CO2
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Hyperthermophile
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Members of the archaea with an optimum growth temperature of 80°C or higher
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Hydrogel
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The matrix that makes up a biofilm
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Catalase
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An enzyme acting upon hydrogen peroxide
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Nitrogen Fixation
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Rhizobium bacteria do this in symbiosis with leguminous plants
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Obligate Aerobe
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Requires atmospheric oxygen to grow
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Microaerophile
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Requires atmospheric oxygen, but in lower than normal concentrations
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Aerotolerant anaerobe
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Does not use oxygen, but grows readily in its presence
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Obligate Anaerobe
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Does not use oxygen and usually finds it toxic
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Peptones
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Important source of energy, carbon, nitrogen, and sulfur requirements in complex media
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Peroxidase
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Breaks down hydrogen peroxide without generation of oxygen
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Hydroxyl Radical
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Formed in cytoplasm by ionizing radiation
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Catalase
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An enzyme that converts hydrogen peroxide into oxygen and water
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Superoxide radicals
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The toxic form of oxygen that is neutralized by superoxide dismutase - synonym for superoxide anions
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Oxyrase
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A component added to some culture media that makes the Petri plate into a self-contained anaerobic chamber
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Streak Plate
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Isolation method for getting pure cultures; uses an inoculating loop to trace a pattern of inoculum on a solid medium
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Spread Plate
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Colonies grow on agar surface for identification
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Differential Medium
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Used to increase the numbers of a small minority of microorganisms in a mixed culture to arrive at a detectable level of microorganisms
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Lyophilization
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Preservation method that uses quick-freezing and a high vacuum
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Colonies
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Accumulations of microbes large enough to see without a microscope
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Inoculum
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Microbes added to initiate growth
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BSL-3
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Usual laboratory designation for safe handling of tuberculosis
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BSL-4
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Laboratory designation for the most dangerous microorganisms; personnel wear "space suits"
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BSL-1
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A routine microbiology teaching laboratory would be designated this
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Stationary phase
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New cell numbers balanced by death of cells
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Lag Phase
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No cell division, but intense metabolic activity
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Log Phase
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A logarithmic plot of the population produces an ascending straight line
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Reducing Media
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Used to grow obligate anaerobes; generally contain ingredients such as sodium thioglycolate that chemically combine with dissolved oxygen
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Selective Media
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Designed to suppress the growth of unwanted bacteria and to encourage growth of desired microbes
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Complex Media
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Nutrients are digests or extracts; exact chemical composition varies slightly from batch to batch
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Polysaccharide
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Agar is a             derived from a marine alga.
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cyanobacteria
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A few bacteria and the photosynthesizing                    

are able to use gaseous nitrogen directly from the atmosphere

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Mesophiles
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The most common microbes; their optimum growth temperatures are 25-40°C
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Nutrient broth
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A complex medium in liquid form
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Absorbance (OD)
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How turbidity is usually recorded in a spectrophotometer
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Dry weight measurement
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How the growth of filamentous bacteria is usually recorded
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Facultative anaerobes
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Grow more efficiently aerobically than they do anaerobically
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Facultative halophiles
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do not require high salt concentrations, but they are able to grow at salt concentrations that may inhibit the growth of many other bacteria.
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Phsophate salts, amino acids, and peptones
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are examples of buffers found in complex media
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Culture Medium
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Any nutrient material prepared fro the growth of bacteria in a laboratory
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Agar
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melts at about the boiling point of water but remains liquid until the temperature drops to about 40°C
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Pour plate method
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Dilutions of a bacterial mixture are poured into a Petri dish and mixed with melted agar; this is a plate counting method.

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Peptones
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Partially digested protein products that are used in complex media
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Living host cells
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Usually necessary to grow obligate intracellular parasites such as rickettsias and chlamydias
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Reduction
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The general term for tests that estimate microbial growth by the time required for them to deplete oxygen in the medium is                   tests.
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Colony-forming Unit
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When a single colony arises from a clump a bacteria, it is recorded as a(n)                      .
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