microbiology an introduction test bank

Correct Answer: A

Rationale: The correct answer is A because the secondary immune response is quicker due to memory B and T cells being already present from the primary response. These memory cells can quickly recognize and respond to the antigen upon re-exposure, leading to a faster and more efficient immune response. Choices B and C are incorrect as the secondary response produces more antibodies and requires fewer antigen stimulations. Choice D is also incorrect as the secondary response is faster than the primary response.

Correct Answer: A

Rationale: Rationale for correct answer (A: Escherichia coli): 1. Endo agar selects for Gram-negative bacteria. 2. Red colonies on Endo agar indicate lactose fermentation, characteristic of E. coli. 3. E. coli is a common cause of pneumonia, especially in immunocompromised patients. Summary of why other choices are incorrect: - B: Klebsiella pneumoniae: Typically forms mucoid colonies on agar. - C: Pseudomonas aeruginosa: Produces characteristic greenish-blue colonies on agar. - D: Proteus mirabilis: Does not typically ferment lactose, so would not produce red colonies on Endo agar.

Correct Answer: A

Rationale: The correct answer is A: Clostridium perfringens. This bacterium is an anaerobic, Gram-positive rod that forms terminal spores and produces gas. It is commonly associated with wound infections and gas gangrene. Clostridium botulinum causes botulism and does not typically present with gas production. Bacillus anthracis is an aerobic, Gram-positive spore-forming bacterium causing anthrax. Clostridium tetani causes tetanus and does not produce gas. Thus, based on the characteristics described in the question, Clostridium perfringens is the most likely causative agent.

Correct Answer: B

Rationale: The correct answer is B (2). During glycolysis, one glucose molecule is broken down into two molecules of pyruvate. In this process, a net gain of 2 ATP molecules is produced through substrate-level phosphorylation. Specifically, ATP is generated during the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate and during the conversion of phosphoenolpyruvate to pyruvate. The other choices are incorrect because the net gain of ATP molecules in glycolysis is not 1, 3, or 4; it is 2 based on the specific enzymatic reactions involved in the pathway.

Correct Answer: A

Rationale: The correct answer is A because the secondary immune response is quicker due to memory B and T cells being already present from the primary response. These memory cells can quickly recognize and respond to the antigen upon re-exposure, leading to a faster and more efficient immune response. Choices B and C are incorrect as the secondary response produces more antibodies and requires fewer antigen stimulations. Choice D is also incorrect as the secondary response is faster than the primary response.