A microbe recovered from an environment sample grows on a medium composed of agar and a mix of salts. The agar is not digested during incubation. The growth rate increases in high CO2 conditions. The organism is likely an _______.
autotroph
A cell that uses an organic carbon source and obtains energy from light would be called a
photoheterotroph
A _____ organism requires oxygen for growth.
obligate aerobic
An aquatic microbe that can grow only near the surface of the water is probably which of the following?
phototroph
An organism that produces catalase enzyme is protected from the harmful effects of
peroxide anion
All of the following are used to protect organisms from the toxic by-products of oxygen EXCEPT
protease
A microbe that grows only at the bottom of a tube of thioglycollate medium is probably a
obligate anaerobe
Nitrogen is a growth limiting nutrient for many organisms because
only a few microbes can extract it from the atmosphere, but all organisms require it for amino acid and nucleotide synthesis
An organism that requires chemical nutrients which serve as final electron acceptors is an
chemotroph
At temperatures higher than the maximum growth temperature for an organism,
hydrogen bonds are broken, proteins are denatured, and membranes become to fluid.
Human pathogens are classified as
mesophiles
In the process of _____ microbes detect the presence and density of other microbes and modify their metabolic activity in response.
quorum sensing
Which of the following organisms would be most likely to contaminate a jar of pickles?
an acidophile
Organisms that can grow with or without oxygen present are
either facultative anaerobes or aerotolerant anaerobes
A fastidious organism might be grown on which of the following types of media?
enriched media
Obligate anaerobes may be cultured in the laboratory
in a reducing medium
Joan wants to discover a microbe capable of degrading an environment contaminant. Which of the following is the process she should use?
enrichment culture
A microbiologist inoculates a growth medium with 100 bacterial cells/ml. If the generation time of the species is 1 hour, and there is no lag phase, how long will it be before the culture contains more than 10,000 cell/ml?
7 hours
An epidemiologist is investigating a new disease and observes what appear to be bacteria inside tissue cells in clinical samples from victims. The scientist wants to try to isolate the bacteria in the lab. What culture conditions are most likely to be successful?
inoculation of cell cultures
Microbial growth rates are controlled in a chemostat by
controlling the amount of a limiting nutrient
MacConkey agar plates represent ______ medium.
both a differential and a selective
A Petroff-Hauser counting chamber is a
glass slide containing an etched grid for counting microbes directly using a microscope
A means of reproduction in which duplicate DNA molecules are separated by cell elongation, followed by formation of a septum to divide the cytoplasm is called
binary fission
A device that removes wastes and adds fresh medium to bacterial cultures in order to prolong the log phase of a culture is called a
chemostat
The ______ of a population is the time it takes for the cells to double in number.
generation time
Which of the following is an indirect method for estimating the number of microbes in a sample?
turbidity
During which growth phase are bacteria more susceptible to antimicrobial drugs?
log phase
The use of salt and sugar in preserving various types of foods is an application of which of the following concepts?
osmotic pressure
A clinical sample labeled as "sputum" was collected from
the lungs
The method of obtaining isolated cultures that utilizes surface area to physically dilute specimens is called
the streak-plate technique
______ are complex communities of various types of microbes that adhere to surfaces.
Biofilms
The ______ method provides an estimate of the CFUs (colony-forming units) in a sample
viable plate-count
Blood agar plates are an example of _____ medium.
differential
Sodium thioglycollate is associated with which of the following types of media?
reducing media
Which of the following quantification techniques can distinguish living cells from dead cells in a culture?
metabolic activity
The correct sequence for the phases indicated by the letters A,B,C and D is
lag phase, log phase, stationary phase, death phase
The generation time of bacterial cells is shortest during the _____ phase.
log
When cells are metabolically active but not dividing, they are in the ____ phase.
lag
Metabolic activity is at maximum level in the _____ phase of growth.
log
Creating conditions in the laboratory that promote the growth of some microbes while inhibiting the growth of others is called
selective enrichment culturing
A laboratory protocol lists the following ingredients: 1 g sucrose, 16.4 g Na2HPO4, 1.5 g (NH4)3PO4, 0.02 g CaCO3, KNO3, water to 1 liter and autoclave. This recipe is for a ______ medium.
defined broth
A capnophile is a microorganism that thrives in conditions of high
carbon dioxide levels
A microorganism found living under conditions of high ____ is a barophile.
hydrostatic pressure
Microaerophiles are microbes that grow best at low
oxygen levels
A 100ul sample containing 1000 bacterial cells/ul in log phase growth is added to 9.9 ml of fresh culture medium broth. assuming no nutrients are in limited supply, and a generation time of 30 minutes, how many bacteria will be present in the entire broth culture after six hours?
4.096 x 108
The conversion of nitrogen gas to ammonia is called nitrogen (metabolism/ fixation).
fixation
Organisms that require organic sources of carbon and energy are called (chemoheterotrophs/ chemoautotrophs/ auxotrophs).
chemoheterotrophs
The (peroxide/ superoxide/ hydroxyl) radical if formed during the incomplete reduction of O2 during electron transport in aerobes.
superoxide
The (optimum/ range/ minimum) growth temperature is the temperature at which an organism exhibits the highest growth rate.
optimum
The preferred method for long term storage of bacteria is (freezing/ refrigeration/ lyophilization).
lyophilization
Alkalinophiles can survive in water up to pH (11.5/ 10/ 7.0).
11.5
Many photosynthetic organisms produce (catalase/ carotenoids/ dismutase) to protect themselves from the damaging effects of singlet oxygen (1O2).
Cartenoids
A (culture/ specimen/ inoculum) is a sample of microorganisms introduced into a growth medium.
inoculum
A pure culture is composed of cells that arise from a single ( cell/inoculum/ sample).
cell
A gelling agent derived from algae that is useful for crating solid growth media is called (broth/ agar/ starch)l
agar
A sample placed into fresh medium is initially in the (lag/ log/ stationary) phase of microbial growth in most instances.
lag
A growth curve plots the (number/ concentration) of viable organisms in a growing population over time.
number
Flow (spectrohotometry/ cytometry) is a method of counting cells that have been stained or tagged with fluorescent dyes.
cytometry
A clinical sample of (urine/ sputum/ tissue) is called a biopsy.
tissue
A (cytometer/ spectrophotometer) can measure changes in the turbidity of a bacterial culture.
spectrophotometer