Correct Answer: A

Rationale: The correct answer is A: Peritoneum. Normal flora refers to the microorganisms that naturally inhabit the human body without causing harm. The peritoneum is a sterile area, so it does not harbor normal flora. The urethra, vagina, and mouth all have normal flora due to their moist and warm environments, which provide an ideal habitat for microorganisms to thrive. The peritoneum, being a sterile cavity that houses organs like the stomach and intestines, does not have a natural microbial population like the other areas mentioned.
Therefore, it does not contain normal flora.

Correct Answer: A

Rationale: The correct answer is A: Mycobacterium tuberculosis. This bacterium is responsible for causing tuberculosis. It is a slow-growing, acid-fast bacillus that primarily affects the lungs. Mycobacterium tuberculosis is transmitted through the air via respiratory droplets.
Choice B, Streptococcus pneumoniae, is a common cause of pneumonia but not tuberculosis.
Choice C, Salmonella enterica, causes food poisoning.
Choice D, Neisseria meningitidis, causes meningitis, not tuberculosis.
Therefore, Mycobacterium tuberculosis is the correct answer based on its characteristics and mode of transmission.

Correct Answer: C

Rationale: The Baltimore classification system categorizes viruses based on their genome type and replication strategy. It divides viruses into seven groups: Group I (dsDN
A), Group II (ssDN
A), Group III (dsRN
A), Group IV (ssRNA(+)), Group V (ssRNA(-)), Group VI (ssRNA-RT), and Group VII (dsDNA-RT). Each group represents a distinct viral genome and replication method.
Therefore, the correct answer is C. The other choices are incorrect because the Baltimore classification system specifically identifies viruses into seven groups, not four, five, or nine.

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known for producing a blue-green pigment called pyocyanin, which gives the characteristic color seen in the wound abscess. The distinctive odor of jasmine is also a key feature of Pseudomonas aeruginosa. Proteus vulgaris (
B) and Klebsiella pneumoniae (
D) do not produce blue-green pigment or have a jasmine-like odor. Escherichia coli (
C) typically does not produce blue-green pigment or have a jasmine-like odor.

Correct Answer: A

Rationale: The correct answer is A: TRUE. Poxviruses are indeed the largest viruses, ranging from 200-450 nm in size, which is close to the resolution limit of a light microscope. This makes them almost visible under a light microscope. The other choices are incorrect because poxviruses are not smaller or uncertain in size (choices B and
C), nor are they partially visible - they are almost visible due to their relatively large size.