free microbiology test bank questions pdf

Correct Answer: B

Rationale: The correct answer is B: Endoplasmic reticulum. Prokaryotic cells lack membrane-bound organelles like the endoplasmic reticulum, which is present in eukaryotic cells. Prokaryotes do possess ribosomes for protein synthesis (A), a chromosome (C) for genetic material, and peptidoglycan (D) in their cell walls. The absence of endoplasmic reticulum is a key characteristic that distinguishes prokaryotic cells from eukaryotic cells.

Correct Answer: A

Rationale: The correct answer is A: Bubonic plague. Bubonic plague is characterized by high fever and large swollen lymph nodes (buboes). The case fatality rate in untreated cases can reach 60%. This form of plague is typically transmitted through the bite of an infected flea. B: Pneumonic plague presents with respiratory symptoms and is transmitted through respiratory droplets. C: Gastrointestinal plague is not a recognized form of plague. D: Septicemic plague is a severe form of plague where the bacteria multiply in the bloodstream. It may not always present with buboes.

Correct Answer: A

Rationale: The correct answer is A: Nucleus. DNA viruses replicate in the host cell's nucleus because they require access to the host cell's DNA replication machinery. The nucleus contains the necessary enzymes and factors for DNA replication to occur accurately. The DNA viruses need to utilize these host cell components to replicate their own genetic material. Summary of why other choices are incorrect: B: Cytoplasm - Cytoplasm lacks the necessary enzymes and machinery for accurate DNA replication. C: Endoplasmic Reticulum - ER is involved in protein synthesis and processing, not DNA replication. D: Golgi Apparatus - Golgi apparatus is responsible for processing and packaging proteins, not DNA replication.

Correct Answer: C

Rationale: The correct answer is C: Bacillus anthracoides. 1. The patient's symptoms align with cutaneous anthrax, caused by Bacillus anthracis. 2. Presence of immobile streptobacilli able of capsulation matches the characteristics of Bacillus anthracis. 3. Symptoms such as black crust, peripheral vesicular rash, and non-painful edema are classic for cutaneous anthrax. 4. Choice A: Bacillus antracis is a misspelling, not a valid option. 5. Choice B: Staphylococcus aureus does not match the symptoms described in the scenario. 6. Choice D: Bacillus megaterium is not associated with cutaneous anthrax.

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.