Your bacterium is growing on a type of medium called casein agar, which contains milk protein (casein). There is a clear zone around the growth area of the bacterium, showing that it is synthesizing the enzymes needed to catalyze the breakdown of casein. These enzymes are considered:
apoenzymes.
exoenzymes.
ribozymes.
regulated enzymes.
endoenzymes.
The Correct Answer is B
A. Apoenzymes: Apoenzymes are the protein portion of enzymes and do not indicate whether the enzyme is secreted or extracellular.
B. Exoenzymes: Exoenzymes are secreted by the cell into the surrounding medium to hydrolyze large extracellular substrates like casein, producing clear zones around colonies.
C. Ribozymes: Ribozymes are RNA molecules with catalytic activity that function mainly inside cells; they are not secreted protein enzymes that digest extracellular proteins like casein.
D. Regulated enzymes: The enzymes degrading casein may be regulated, but the defining feature shown (activity outside the colony) is secretion, so regulated describes control rather than location of action.
E. Endoenzymes: Endoenzymes act inside the cell; enzymes that produce extracellular clearing of casein are acting outside the cell and therefore are not endoenzymes.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. Antiseptic: Antiseptics are chemical agents suitable for application to living tissue to reduce microbial load on skin and mucous membranes before invasive procedures.
B. Disinfectant: Disinfectants are intended for inanimate surfaces and are often too harsh or toxic for direct use on patient skin.
C. Surfactant: Surfactants (detergents) help remove soils and some microbes but are not the primary agents used to achieve surgical skin antisepsis.
D. Antibiotic: Systemic or topical antibiotics treat or prevent infection but are not the standard topical agent used to prepare skin immediately before surgery.
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.
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