객관식
Which organism is not correctly matched to its energy source?
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1. Introduction to Microbiology
Members of the Bacterial World
객관식
Which of the following characteristics would most likely rule out Pseudomonas as the identity of an unknown bacterial isolate?
A
The bacterium is motile by means of polar flagella.
B
The bacterium is oxidase positive.
C
The bacterium is Gram-positive.
D
The bacterium produces a green pigment.
검증된 단계별 안내1
Step 1: Understand the typical characteristics of Pseudomonas species. Pseudomonas are generally Gram-negative bacteria, motile by polar flagella, oxidase positive, and often produce a green pigment called pyocyanin.
Step 2: Analyze each characteristic given in the problem in relation to Pseudomonas traits: motility by polar flagella is consistent with Pseudomonas, oxidase positivity is also typical, and green pigment production aligns with known Pseudomonas pigments.
Step 3: Focus on the Gram stain characteristic. Since Pseudomonas are Gram-negative, a Gram-positive result would contradict this fundamental trait and thus rule out Pseudomonas as the identity of the isolate.
Step 4: Conclude that the characteristic which most likely rules out Pseudomonas is the bacterium being Gram-positive, because this is a key differential feature in bacterial classification.
Step 5: Summarize that when identifying bacteria, Gram stain results are critical initial tests that help narrow down possible genera, and a Gram-positive result excludes Gram-negative genera like Pseudomonas.
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