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chapter 7 microbial nutrition ecology & growth
chapter 7 from microbiology a systems approach, cowan & talaro
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Microbiology
02/28/2010

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Term
Aerobe
Definition
A microorganim that lives and grows in the presence of free gaseous oxygen (O2)
Term
Anaerobe
Definition
A microorganism that grows best, or exclusively, in the absence of oxygen
Term
Binary Fision
Definition
The formation of two new cells of approximately equal size as the result of parent cell division
Term
Commensalism
Definition
An unequal relationship in which one species derives benefit without harming the other.
Term
Diffusion
Definition
The dispersal of molecules, ions or microscopic particles propelled down a concentration gradient by spontandious random motion to achieve a uniform distribution.
Term
Essential nutrient
Definition
Any ingredient such as a certain amino acid, fatty acid, vitamin or mineral that cannot be formed by an organism and must be supplied in the diet. A growth factor.
Term
Heterotroph
Definition
An organism that relies on organic compounds for its carbon and energy needs.
Term
Lag phase
Definition
the early phase of population growth during which no signs of growth occur
Term
normal microbial flora
Definition
the native microbial forms that an individual harbors.
Term
nutrients
Definition
any chemical substance that must be provided to a cell for normal metabolism and growth. Macronutrients are required in large amounts and micronutrients in small amounts.
Term
Obligate
Definition
Without alternative; restricted to a particular characteristic. Ex: an obligate parasite survives and grows only in a host; an obligate aerobe must have O2 to grow; an obligate anaerobe is destroyed by O2.
Term
Opportunistic
Definition
An infection, ordinarily nonpathenogenic or weakly pathogenic microbes, that causes disease primarily in immunologically compromised host.
Term
Parasite
Definition
An organism that lives on or within another organism (host), from which it obtains nutrients and enjoys protection. Produces some degree of harm in the host.
Term
Pathogen
Definition
Any agnet, usually a virus, bacterium, fungus, protozoan or helminth, that causes disease.
Term
Photoautotroph
Definition
An organism that utilizes light for its energy and carbon dioxide mainly for its carbon needs.
Term
Saprobe
Definition
A microbe that decomposes organic remains from dead organisms. Also known as a sprophyte or saprotroph.
Term
Symbiosis
Definition
An intimate association between individuals from two species; used as a synonym for mutualism.
Term
What kind (mesophile, psychrophile, thermophile) of organism is typically associated with human disease?
Definition
Mesophile (optimal growth/metabolism is from 20-40 degrees C)
Term
What kind (mesophile, psychrophile, thermophile) of organism is typically responsible for food poisoning?
Definition
Psychrophile (optimal growth/metabolism is from 0-15 degrees C)
Term
What will happen to the growth of a thermophile adapted to 67 degrees C when it is grown at 55 degrees C?
Definition
It will continue to grow/thrive because it's still in the optimum growth/metabolism range of 45-80 degrees C; 70 degrees C is ideal.
Term
Where does a capnophile live?
Definition
In environments with a higher-than-normal concentration of carbon dioxide.
Term
Define autotroph
Definition
Self-feeder; A microorganism that requires only inorganic nutrients and whose sole source of carbon is carbon dioxide.
Term
Define phototroph
Definition
Microbes that use photosynthesis (sunlight) to feed; they derive their energy from sunlight & transform light rays into chemical energy.
Term
An organism adapted to saltwater is transported to a freshwater lake. Will osmosis cause it to shrink, swell or show no change?
Definition
Swell. That's because water moves toward the higher solute concentrated areas ... this is a hypotonic situation.
Term
How does diffusion differ from active transport?
Definition
Diffusion is the net movement of molecules from a high concentration area to a low-concentration area; there's no semi-permeable membrane; no energy is expanded.

Active transport requires energy (ATP)
Term
How do the terms osmosis and chemiosmosis differ?
Definition
Osmosis is diffusion of water through a permeable but selective membrane.

Chemiosmosis is diffusion of a chemical other than water.
Term
How do amoebas drink?
Definition
Pinocytosis. They engulf droplets of water to bring into the cell (active transport).
Term
What happens when a facultative anaerobe is placed in an oxygen-free environment?
Definition
A facultative anaerobe adapts, uses anaerobic respiration or fermentation.
Term
What happens when an obligate anaerobe is placed in an oxygen-free environment?
Definition
An obligate anaerobe will grow and metabolize in an oxygen-free environment because O2 isn't needed, and is in fact toxic to the cell.
Term
Coral reefs are a symbiotic relationship between and algae and a microscopic animal where both benefit ... what is this termed?
Definition
Mutualism (rely on each other for growth)
Term
What kind of relationship exists between humans and Plasmodium?
Definition
Parasitism (host/microbe relationship where the host is negatively impacted)
Term
During stationary phase, cells are dividing and dying at (constant, lagarithmic, flat or geometric) rates?
Definition
Flat (equal)
Term
What is the definition of generation time?
Definition
The time it takes for one cell to divide; The time required for a complete fission cycle - from parent cell to two new daughter cells. Also called doubling time.
Term
Describe three ways of determining the number of bacteria in a culture.
Definition
1. Turbidity: % of light transmitted through test-tube. the greater the turbidity, the larger the population size.
2. Direct cell count: count the total dead/live cells in special microscopic slide with a pre-measured grid.
3. Standard Plate Count: Start with unknown concentration of specimen; take mL and add to 99 mL of water; take 1 mL of that solution and add to 99 mL of water; repeat 2 more times; count the colonies in last solution when poured onto plate w/agar.
Term
Spring water has (more/fewer) water molecules than pure water or sea water?
Definition
Fewer
Term
Sea water has (more/fewer) water molecules than pure water?
Definition
Fewer
Term
What is the purest type of water?
Definition
18 Mega-ohm water
Term
Amoebas are in what Kingdom?
Definition
Protista
Term
In osmosis, water moves from a ______ to a _____ concentration of water molecules.
Definition
higher to lower
Term
The source of the necessary elements of life is...
Definition
an inorganic environmental resevoir
Term
An organism that can synthesize all its required organic components from CO2 using energy from the sun is a ...
Definition
Phtotoautotroph
Term
Chemoautotrophs can survive on ______ and ______ alone.
Definition
minerals and CO2
Term
All organisms require _____________ nutrients.
Definition
inorganic
Term
A pathogen would most likely be described as: parasite, commensal, saprobe or symbiont?
Definition
parasite
Term
Passive transport requires a __________.
Definition
gradient
Term
A cell exposed to a hypertonic environment will _______ by osmosis.
Definition
lose water
Term
Psychrophiles would be expected to grow __________________.
Definition
at refrigerator temperatures
Term
Superoxide ion is toxic to strict anaerobes because they lack _____________.
Definition
dismutase
Term
In a viable plate count, each ______ represents a _______ from the sample population.
Definition
colony; cell
Term
An organic nutrient essential to an organism's metabolism is caled a ______ factor.
Definition
growth