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openstax microbiology test bank Questions
Question 1 of 5
Extrachromosomal carriers of the genetic information in bacteria are:
Correct Answer: B
Rationale: The correct answer is B: Plasmids. Plasmids are extrachromosomal DNA molecules found in bacteria that can replicate independently of the bacterial chromosome. They carry additional genetic information, such as antibiotic resistance genes or virulence factors. Mesosomes (choice A) are not involved in carrying genetic information; they are infoldings of the cell membrane. Ribosomes (choice C) are cellular organelles responsible for protein synthesis, not carriers of genetic information. Choice D is incorrect as plasmids are indeed extrachromosomal carriers of genetic information in bacteria.
Question 2 of 5
Bacteria associated with hospital-acquired infections:
Correct Answer: B
Rationale: The correct answer is B: Pseudomonas aeruginosa. This bacterium is commonly associated with hospital-acquired infections due to its ability to survive in hospital environments, resist antibiotics, and infect immunocompromised patients. Streptococcus pneumoniae (choice A) is more commonly associated with community-acquired pneumonia. Vibrio cholerae (choice C) causes cholera, a waterborne disease, and is not typically associated with hospital-acquired infections. Choice D is incorrect because Pseudomonas aeruginosa is indeed associated with hospital-acquired infections.
Question 3 of 5
A smear of sputum from the patient with suspected lobar pneumonia was stained with the use of the following stains and reagents: solution of gentian violet, Lugol’s solution, 960 alcohol, watermagenta. What staining method was applied in this case?
Correct Answer: A
Rationale: The correct answer is A: Gram staining method. The rationale is as follows: 1. Gentian violet is a primary stain used in the Gram staining procedure to stain the bacterial cells. 2. Lugol's solution is a mordant that helps to fix the crystal violet stain in Gram-positive bacteria. 3. 95% alcohol is used as a decolorizing agent in the Gram staining process to remove the stain from Gram-negative bacteria. 4. Watermagenta is not a standard reagent in the Gram staining method. Therefore, based on the reagents mentioned, the staining method applied in this case is the Gram staining method. Other choices are incorrect: B: Ziehl-Nielsen's - This staining method is used for acid-fast staining, not for lobar pneumonia. C: Romanovsky - This staining method is used for blood smears, not for bacterial staining in pneumonia. D: Neisser - This staining method is not commonly used in routine bacterial staining procedures.
Question 4 of 5
Which of the following is an active transport mechanism?
Correct Answer: D
Rationale: The correct answer is D: pinocytosis. This is an active transport mechanism where cells engulf fluids or solutes through vesicles. Energy is required to transport substances against a concentration gradient. A is incorrect as pinocytosis is an active process, not passive like pinocytosis. B is incorrect as facilitated diffusion is a passive process that uses carrier proteins to move substances down a concentration gradient. C is incorrect as filtration is a passive process that relies on pressure gradients to move substances across a barrier. Therefore, D is the correct choice as it involves the active transport of substances into the cell.
Question 5 of 5
Conidiospores that bud off from a vase-shaped spore-bearing cell are referred to as:
Correct Answer: C
Rationale: The correct answer is C: phialospores. Phialospores are conidiospores that bud off from a vase-shaped spore-bearing cell called a phialide. This structure is characteristic of fungi in the genus Penicillium. Arthrospores (A) are formed by the fragmentation of hyphae, porospores (B) are not a recognized term in mycology, and blastospores (D) are produced by budding from yeast cells. Therefore, C is the correct choice based on the specific description provided in the question.