Sulfanilamide is an antimicrobial drug that mimics the shape of an important substrate for a particular bacterial enzyme and can bind in its active site, thereby inhibiting the enzyme. This type of inhibition is known as
allosteric inhibition.
competitive inhibition.
excitatory allosteric control.
noncompetitive inhibition.
feedback inhibition.
The Correct Answer is B
A. Allosteric inhibition:
Allosteric inhibition involves a molecule binding at a site other than the active site to change enzyme activity; the described action is binding at the active site, so this does not match.
B. Competitive inhibition:
A competitive inhibitor resembles the substrate and competes for binding at the enzyme’s active site; binding prevents the actual substrate from occupying the active site, which fits the description of sulfanilamide.
C. Excitatory allosteric control:
This term implies activation via an allosteric site rather than inhibition at the active site and does not describe substrate mimicry binding the active site.
D. Noncompetitive inhibition:
Noncompetitive inhibitors bind at a different site and reduce enzyme activity regardless of substrate concentration; they do not typically resemble the substrate or compete for the active site.
E. Feedback inhibition:
Feedback inhibition occurs when an end product of a metabolic pathway inhibits an enzyme earlier in that pathway, usually via allosteric binding; the scenario describes direct active-site competition rather than pathway end-product regulation.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A. The temperature of their environment: Temperature strongly affects enzyme activity, membrane fluidity, and overall metabolism, and thus directly influences microbial growth.
B. The acidity of their environment: Environmental pH affects enzyme function and membrane stability and is therefore a key factor in microbial growth.
C. The presence of non-essential nutrients: Non-essential nutrients are those the organism can synthesize or do not require for growth; their presence typically does not determine whether growth occurs, so they have minimal influence compared with essential factors.
D. The other microbes sharing their environment: Interactions with other microbes (competition, cooperation, predation, antibiotic production) can strongly influence growth rates and community composition.
Correct Answer is A
Explanation
A. Use a pressure cooker to sterilize the bottles, in steam: Steam under pressure (autoclaving or a pressure cooker) achieves high temperatures (e.g., 121 °C / 250 °F) with moist heat that inactivates microbes and spores much faster than dry heat ovens; switching to steam under pressure will greatly shorten sterilization time.
B. Increase the temperature of the oven by 5 degrees: A 5 °F increase is negligible relative to the large temperature and time changes required for faster sterilization and would not meaningfully speed up the process.
C. Pour an antimicrobial chemical into the bottles before placing into the oven: Adding chemicals may leave residues that are unsafe for baby feeding and would not substitute for validated sterilization; it also may not speed thermal sterilization.
D. Place the bottles outside in the sunlight and then place in the oven: Sunlight has limited disinfection ability (UV exposure) and will not meaningfully reduce the time required for oven sterilization; this step would not reliably speed the process.
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