microbiology an introduction 13th edition test bank -Nurselytic

Correct Answer: A

Rationale: The correct answer is A: protein envelope around the nucleic acid. Viral capsid is the protein coat that surrounds and protects the viral nucleic acid (DNA or RN
A). This structure helps in protecting the genetic material from degradation and facilitates the attachment of the virus to host cells. Option B is incorrect as it suggests the nucleic acid is coated with protein, which is not the case. Option C is incorrect as not all viruses have an outer membrane. Option D is incorrect as viruses typically do not have a lipoprotein membrane.

Correct Answer: D

Rationale: The correct answer is D because Mycobacterium tuberculosis is a straight or slightly curved rod with occasional polymorphism. This bacterium does not conform to the characteristics of gram-negative coccus (
A), gram-positive coccus (
B), or gram-negative rod (
C). Mycobacterium tuberculosis is characterized by its unique cell wall composition, which includes high lipid content and mycolic acids, contributing to its acid-fast staining property. The other choices are incorrect because they do not accurately describe the morphology of Mycobacterium tuberculosis.

Correct Answer: A

Rationale: The correct answer is A: Absence of a cell wall. L-form transformation is a phenomenon where the pathogen loses its cell wall, making it resistant to antibiotics like penicillin. The absence of a cell wall allows the pathogen to survive in a hostile environment.


Choice B: Absence of flagella is incorrect because flagella are responsible for motility and not directly related to L-form transformation.


Choice C: Absence of a capsule is incorrect as the capsule is a protective layer outside the cell wall and not affected by L-form transformation.


Choice D: Absence of a spore is incorrect because spores are a dormant form of bacteria and not related to L-form transformation.

Correct Answer: B

Rationale: The correct answer is B because transformation in bacteria refers to the uptake of naked DNA from the environment. During transformation, bacteria take up free DNA from their surroundings and incorporate it into their own genome. This mechanism allows bacteria to acquire new genetic material and traits.

Explanation for other choices:
A: Transfer of DNA via phages refers to transduction, not transformation.
C: Transfer of DNA via direct contact is known as conjugation, not transformation.
D: Spore formation is a method of bacterial survival but is not related to transformation.

Correct Answer: A

Rationale:
Step 1: Vibrio cholerae is a bacterium known to cause cholera, a foodborne illness transmitted through contaminated water.

Step 2: Cholera outbreaks are often linked to unsanitary water sources, making Vibrio cholerae the correct choice.

Step 3: Clostridium difficile causes gastrointestinal infections, not typically associated with contaminated water.

Step 4: Mycobacterium tuberculosis causes tuberculosis, a respiratory disease, not related to foodborne illnesses.

Step 5: Neisseria gonorrhoeae is a sexually transmitted bacterium, not linked to foodborne illnesses from contaminated water.