microbiology basic and clinical principles test bank

Correct Answer: B

Rationale: The growth of bacteria is a result of water adsorption because water is essential for various metabolic processes within the bacterial cells, such as nutrient uptake, energy production, and waste removal. Water serves as a medium for chemical reactions to occur and provides structural support to the bacteria. Without sufficient water, bacteria cannot thrive and reproduce. A: Air consumption is incorrect because while bacteria may require oxygen for respiration, it is not the primary factor for their growth. C: Enzyme production is incorrect because enzymes are important for various cellular functions but do not directly influence bacterial growth. D: Radio isotopes are incorrect as they are not essential for bacterial growth and can even be harmful to bacterial cells.

Correct Answer: B

Rationale: Step-by-step rationale for why choice B (Tuberculin is introduced) is correct: 1. Tuberculin test helps identify individuals with latent TB infection. 2. Negative skin-allergic samples suggest absence of active TB. 3. Introducing tuberculin can help confirm latent TB infection. 4. Antibiotics are not prescribed for negative skin-allergic samples. 5. Vaccines are not administered for TB diagnosis. Summary: - Choice A is incorrect as antibiotics are not prescribed for negative skin-allergic samples. - Choice C is incorrect as vaccines are not used for TB diagnosis. - Choice D is incorrect as introducing tuberculin is the appropriate step in this scenario.

Correct Answer: A

Rationale: The correct answer is A: Streptococcus pyogenes. 1. Gram-positive cocci in chains suggest streptococci. 2. Beta-hemolytic activity indicates Streptococcus pyogenes. 3. Streptococcus pyogenes is commonly associated with sore throat (pharyngitis) and fever. 4. Streptococcus pneumoniae (choice B) is alpha-hemolytic and mainly causes pneumonia. 5. Enterococcus faecalis (choice C) is not typically associated with sore throat. 6. Staphylococcus aureus (choice D) is not commonly beta-hemolytic and is not a typical cause of pharyngitis.

Correct Answer: A

Rationale: The correct answer is A: Vibrios. Vibrios are gram-negative curved bacteria that are motile and do not form spores or capsules. The description of the bacteria in the question fits the characteristics of Vibrios. Vibrios are commonly found in aquatic environments and some species can cause gastrointestinal infections in humans. B: Spirochetes are also gram-negative curved bacteria, but they are spiral-shaped and have unique axial filaments for motility. The description in the question does not match the characteristics of spirochetes. C: Clostridia are gram-positive, spore-forming bacteria. The question specifically states that the bacteria are gram-negative and do not form spores, ruling out Clostridia. D: Corynebacteria are gram-positive, non-spore-forming bacteria. The description in the question does not match the characteristics of Corynebacteria.

Correct Answer: B

Rationale: Rationale: The correct answer is B because virulence factors of bacteria are characteristics that enable them to cause disease. Colonization allows bacteria to establish and multiply in the host. Invasion refers to the ability to penetrate host tissues. Toxins are substances produced by bacteria that harm the host. Adhesion is crucial for bacteria to attach to host cells. A: Size and mutation are not typical virulence factors. Resistance is not directly related to causing disease. C: While toxins and evasion of body defenses are correct, motility and size are not universally considered virulence factors. D: Chemotaxis and fermentation are not primary virulence factors, unlike colonization and toxins.