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if you are designing an experiment involving a photolithotrophic autotroph, in addition to light, which of the following would be most essential to maintaining growth of the organism?

a source of CO2

35 colonies grew in nutrient agar from 1.0ml of sample withdrawn from a solution diluted to 10^-5 in a standard plate count procedure. how many cels were in the original sample?


methanogens are potentially of great importance because...

they produce methane, and methane is an excellent energy source

cyanobacteria have,,,

a gram-negative cell wall

pseudomonads are a large group of bacteria which can...

spoil refrigerated food because they grow at 4C, cause disease in plants and animals, use a number of different substances for carbon and energy sources, and degrade proteins and lipids

when a young, vigorously growing culture of bacteria is transferred to fresh medium of different composition, the lag phase is usually short of absent


which of the following is a desirable general characteristic of antimicrobial drugs

selective toxicity, broad spectrum of activity, and bactericidal rather than bacteriostatic

the lowest concentration of an antibiotic that prevents growth is

minimal inhibitory concentration (MIC)

The chlamydias are

obligate intracellular parasites

methanogenic Archaea are

obligate anaerobes that produce methans

which of the following does not effect the concentration of a drug in the body

broad spectrum of activity

which of the following is useful mechanism of action for an antibacterial drug

inhibition of cell wall synthesis, inhibition of protein synthesis, interference with RNA and DNA synthesis

A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called ______ culture system


agents that are static and therefore do not kill infecting microorganisms are not useful as chemotherapeutic agents


heliobacter pylori is responsible for

peptic ulcer disease

the drug of last resort that is generally used in treating infections caused by methicillin resistant staphylococcus aureus is


which of the following affects the size of the clear zone in a disk diffusion test of antimicrobial susceptibility

the initial concentration of the drug, solubility of the drug, the diffusion rate of the drug

in order to determine the minimal lethal concentration (MLC) the culture is first inoculated into a medium containing the drug then subcultured into a medium containing

no drug

elements that are required in relatively large amounts by microorganisms are called


organisms that can use carbon dioxide as their sole or principal source of carbon are


which of the following can be used to isolate pure cultures of bacteria from mixtures

streak plate, spread plate, pour plate

organisms that obtain energy from light are


a wide variety of microorganisms are commercially used to manufacture ______ for human consumption


___________ membranes allow some molecules to pass but not others

selectively permeable

agar is an excellent gelling agent microbiological media because

it is not degraded by most microorganisms and solid agar remains solid until the temperature is raised to 100C and liquid agar remains liquid if the temperature is lowered to 45C are correct

the movement of molecules across a membrane from an area of higher concentration to an area of lower concentration with the use of a carrier molecule embedded in the membrane is called

facilitated diffusion

whooping cough is caused by

bordetella pertussis

the spirochetes include the causative agents for

lyme disease

which of the following is the major reason why it has been difficult to treat viral infections with chemotherapeutic agents?

viruses use the metabolic machinery of their hosts, which limits many of the potential points of attack

coxiella burnetii is responsible for


the most selective antibacterial agents are those that interfere with bacterial cell wall synthesis. This is because ...

bacterial cell wall snythesis is easily inhibited whereas animal cell wall synthesis is more resistant to the actions of the drugs

chemotherapeutic agents that are chemically modified natural products of microorganisms are most specifically referred to as...

semisynthetic drugs

organisms that ignore oxygen and grow equally well in its presence of absence is called


which of the following is a reason for the occurrence of a lag phase in a bacterial growth curve

cells may be old, the medium may be different, organisms could have been injured and need time to recover

an organism with a temperature growth optimum near 80C and a pH growth optimum between 1.0 and 6.5 is usually referred to as


chlamydiae are incapable of producing their own ATP and must rely on their host to supply it


the total number of viable microorganisms remains constant in stationary phase because

either there is a balance between cell divisions and cell death, or there is a cessation of cell division even though the cells may remain metabolically active

which of the following processes can be used to bring nutrients into a cell against a concentration gradient

active transport

members of the genus Rhizobium...

grow symbiotically in root nodules of legumes where they fix nitrogen

the process of conversion of ammonia to nitrate is referred to as


members of the genus Neisseria cause which of the following human diseases


the causative agent of cholera in humans is a member of the genus


which of the followinmg is used by microorganisms to become resistant to a particular drug

enzymatic inactivatino of the drug, exclusion of the drug from the cell, an alternate metabolic pathway that bypasses the drug-sensitive step

which of the following is not a major class of growth factors

nucleic acids

which of these methods can be used to determine the number of viable microorganisms in a sample

measuring colony forming units per ml

organisms that are damaged by normal atmospheric levels or oxygen (20%) but require oxygen levels of 2-10% for growth are called


organisms that do not require oxygen for growth but grow better in its presence are called

facultative anaerobes

most microorganisms maintain their internal pH

near neutral pH7

which of the following can be used to estimate the number of microorganisms in a culture

direct counts of microbial cells, counts of viable cells using colony growth procedures, measurement of microbial biomass

defining features of the halobacteria include

absolute dependence on a high concentration of NaCl for growth

which of the following contribute to the differences between archaea and bacteria

archaea lack muramic acid

the length of the lag phase of growth can vary depending on

the condition of microorganisms, the nature of the growth medium, the temperature

which of the following groups of photosynthetic bacteria are capable of oxygenic photosynthesis

the cyanobacteria

the infectious stage of chlamydiae is called...


gliding motility can be used to propel bacteria

across a solid substrate

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