free microbiology test bank questions pdf

Correct Answer: A

Rationale: The correct answer is A: Bacillus anthracis. This bacterium is known to cause anthrax, a serious infectious disease in humans and animals. Bacillus anthracis is a gram-positive, spore-forming bacterium that produces toxins leading to the characteristic symptoms of anthrax. Clostridium tetani causes tetanus, Mycobacterium tuberculosis causes tuberculosis, and Streptococcus pneumoniae causes pneumonia, none of which are related to anthrax. Therefore, based on the specific pathogen responsible for anthrax, Bacillus anthracis is the correct answer.

Correct Answer: D

Rationale: Step-by-step rationale: 1. The study results indicate water contamination. 2. Contaminated water poses health risks. 3. Therefore, the correct interpretation is that water is contaminated. Summary: - Choice A is incorrect as safety is not confirmed. - Choice B is too mild given the severity of contamination. - Choice C is also incorrect, as it does not accurately reflect the study findings.

Correct Answer: C

Rationale: Rationale: 1. Presence of gram-negative bacilli suggests Enterobacteriaceae family, which includes E. coli. 2. Green soluble pigment indicates pyocyanin production, characteristic of E. coli. 3. E. coli is the most common cause of acute cystitis due to its ability to colonize the urinary tract. Summary: A: Pseudomonas aeruginosa is not typically associated with acute cystitis and does not produce mucous colonies. B: Klebsiella pneumoniae may cause UTIs, but does not produce green pigment and is less common than E. coli. D: Salmonella enteritidis is associated with gastrointestinal infections, not cystitis.

Correct Answer: B

Rationale: The correct answer is B: Herpangina. Family Parvoviridae includes Parvovirus B19, which causes Fifth disease, aplastic crisis in chronic anemia, and fetal infections. Herpangina is caused by Enteroviruses, not Parvoviridae. Parvovirus B19 specifically targets erythroid progenitor cells, leading to anemia in susceptible individuals. Fetal infections can result in hydrops fetalis. Aplastic crisis occurs in patients with chronic anemia due to suppression of erythropoiesis by the virus.

Correct Answer: A

Rationale: The correct answer is A: Viruses. Viruses are acellular, meaning they lack cellular structure, protein synthesizing ability, enzymes, and energy systems. They are essentially genetic material (DNA or RNA) enclosed in a protein coat. Fungi (B), bacteria (C), and protozoa (D) are all cellular organisms with protein synthesizing, enzyme, and energy systems. Viruses rely on host cells to replicate and carry out metabolic functions, making them distinct from other groups.