NURSING EXAM QUESTIONS
MICROBIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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a selective medium.
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a differential medium.
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an enrichment culture.
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both a selective and differential medium.
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Detailed explanation-1: -e. 14. A culture medium on which only gram-positive organisms grow and a yellow halo surrounds Staphylococcus aureus colonies is called a(n) Selective medium.
Detailed explanation-2: -Gram-positive cocci include Staphylococcus (catalase-positive), which grows clusters, and Streptococcus (catalase-negative), which grows in chains. The staphylococci further subdivide into coagulase-positive (S. aureus) and coagulase-negative (S. epidermidis and S. saprophyticus) species.
Detailed explanation-3: -The answer is (d) Stationary phase. This is because penicillin targets the cell wall of bacteria, and gram-positive bacteria have a thicker cell wall than gram-negative bacteria. Therefore, they will be most susceptible to penicillin during the stationary phase when they are actively synthesizing cell wall components.