microbiology chapter 13 test bank

Correct Answer: B

Rationale: The correct answer is B: eukaryotic. Eukaryotic cells have a well-defined nucleus that encloses the genetic material. The nucleus is a distinguishing feature of eukaryotic cells, separating them from prokaryotic cells (choice A) which lack a nucleus. Anucleate cells (choice C) are cells that do not have a nucleus at all. Haploid cells (choice D) contain a single set of chromosomes, but this does not necessarily imply the presence of a nucleus. Therefore, the presence of a nucleus is what categorizes cells as eukaryotic.

Correct Answer: B

Rationale: The correct answer is B: Capsule. Capsules are a protective layer outside the bacterial cell wall that helps bacteria evade phagocytosis by immune cells. The capsule inhibits phagocytic cells from engulfing the bacteria, making it difficult for them to be recognized and destroyed. A: Flagella - Flagella are not involved in protecting bacteria from phagocytosis. They are responsible for bacterial movement. C: Endospore - Endospores are dormant, resistant structures formed by some bacteria in response to harsh conditions. They do not directly protect against phagocytosis. D: Pili - Pili are hair-like structures used for adhesion and conjugation, not for protection against phagocytosis.

Correct Answer: C

Rationale: The correct answer is C: green monkeys. The Marburg virus was first identified in 1967 in Marburg and Frankfurt, Germany, after outbreaks in lab workers exposed to infected African green monkeys. These monkeys were imported from Uganda. The virus is believed to be originally endemic in certain species of African bats and is transmitted to humans through contact with infected animals. Choice A, laboratory rats, is incorrect as the virus did not originate from rats. Choice B, birds, and Choice D, wild turkeys, are also incorrect as there is no evidence linking these animals to the transmission of the Marburg virus.

Correct Answer: D

Rationale: The correct answer is D: Chocolate agar. Neisseria meningitidis is a fastidious organism that requires enriched media for growth. Chocolate agar contains heat-treated blood that provides essential nutrients for the growth of N. meningitidis. The other choices, A: Levine agar, B: Lowenstein-Jensen agar, and C: TCBS agar, do not provide the specific nutrients required for the growth of N. meningitidis. Therefore, only choice D, Chocolate agar, supports the growth of N. meningitidis due to its enriched composition.

Correct Answer: A

Rationale: The correct answer is A: Streptococcus pyogenes. This bacterium fits all the given characteristics: Gram-positive cocci arranged in chains, catalase-negative, and beta-hemolytic on blood agar. Streptococcus pyogenes is known for causing skin and soft tissue infections. Staphylococcus aureus (B) is catalase-positive and typically forms clusters, not chains. Enterococcus faecalis (C) is catalase-negative but not beta-hemolytic. Micrococcus luteus (D) is catalase-positive and not typically associated with wound infections.