T or F Micro 2 test
The usefulness of agar in solidifying microbiological growth media is limited because it does not remain solid at temperatures about 28 degrees C.
False
Ultraviolet radiation is generally more harmful than ionizing radiation.
False
When a young, vigorously growing culture of bacteria is transformed to fresh medium of the different composition, the lag phase is usually short or absent.
False
The Michaelis constant (Km) of an enzyme is the substrate concentration that produces maximum velocity.
False
Blood agar is both a differential and enriched medium.
True
Alcohols are widely used as antiseptic and disinfectants because they are effective against endospores as well as vegetative cells.
False
Dry heat methods usually require lower temperatures and shorter exposure times than moist heat methods to achieve the same degree of killing because of the drying effects of this form of heat.
False
During the lag phase of microbial growth, the cells are metabolically inactive.
False
Germicides kill all pathogenic organisms and endospores.
False
Grisofulvin is used to treat systemic mycoses.
False
Phosphorous can be obtained from organic sources only.
False
A drug that disrupts a microbial function not found in animal cells usually has a lower therapeutic index.
False
A drug that disrupts a microbial function not found in animal cells usually has a higher therapeutic index.
True
Aerobic organisms do produce protective enzymes called superoxide dismutase and catalase.
True
Dry heat methods usually require higher temperatures and longer exposure times than moist heat methods to achieve the same degree of killing because of the drying effects of this form of heat.
True
Endospores have a high content of dipicolinic acid.
True
Ethylene oxide can be used to sterilize materials in sealed plastic wrap because it can penetrate the wrapping material.
True
Grisofulvin is used to treat superficial mycoses
True
Heavy metals are effective antimicrobial agents but are not widely used because of their high toxicity to humans.
True
One of the major advantages of a continuous culture system is that the cells can be maintained in the exponential growth phase for extended periods of time.
True
Penicillin is frequently injected but not normally given orally because it is rapidly degraded in the stomach.
True
Permease proteins that aid in the transport of nutrients resemble enzymes in their specificity for the substance to be transported. Each carrier is selective and will transport only a closely related set of substances.
True
The Michaelis constant (Km) of an enzyme is the substrate concentration that produces half velocity.
True
The effects of most antimicrobial drugs are greater if the microorganisms are actively growing.
True
The primary mechanism by which DNA is damaged by ultraviolet radiation involves the formation of thymine dimmers.
True
The rate of killing by an antimicrobial agent may slow when the microbial population has been greatly reduced because the remaining population may have a higher proportion of resistant organisms.
True
The trace amounts of micronutrients needed by microorganisms can usually be supplied in water and regular media components.
True
Treatment of fungal infections is more difficult than treatment of bacterial infections because the greater metabolic similarity between the fungi and their hosts limits the ability of a drug to have selective toxicity.
True
Ultraviolet radiation is an effective means of sterilizing surfaces.
True
Water activity is inversely proportional to osmotic pressure
True
When a young, vigorously growing culture of bacteria is transformed to fresh medium of the same composition, the lag phase is usually short or absent.
True
