microbiology chapter 1 test bank

Correct Answer: B

Rationale: The correct answer is B because the capsule of bacteria is mainly composed of polysaccharides or polypeptides. This outer layer helps bacteria evade the host's immune system and protects them from desiccation. Peptidoglycan (choice A) is a component of the bacterial cell wall, not the capsule. Flagellin (choice C) is a protein component of the bacterial flagella, not the capsule. Choice D is incorrect as the capsule is indeed composed of polysaccharides or polypeptides.

Correct Answer: B

Rationale: The correct answer is B because peritrichous bacteria have flagella distributed all over their surface, allowing them to move in various directions. Choice A is incorrect because bacteria with a single flagellum at one pole are called monotrichous. Choice C is incorrect as bacteria with a single flagellum at each pole are known as amphitrichous. Choice D is incorrect because peritrichous bacteria have multiple flagella all over their surface, not limited to one or both poles.

Correct Answer: B

Rationale: The correct answer is B: Tuberculosis and mycobacterioses. Mycobacterium tuberculosis, the causative agent of tuberculosis, and other mycobacteria can survive in the soil for extended periods. Here's the rationale: 1. Mycobacteria have a waxy cell wall that provides resistance to harsh environmental conditions. 2. The slow growth rate of mycobacteria allows them to persist in the soil for long periods. 3. Tuberculosis and mycobacterioses are known to be transmitted through environmental exposure, including soil. 4. Colibacillosis and cholera (Choice C) are caused by enteric bacteria that do not survive well in soil. 5. Leptospirosis and plague (Choice D) are bacterial diseases transmitted through animal hosts and are not known to be soil-borne.

Correct Answer: A

Rationale: The correct answer is A: Salk and Sabin vaccines are vaccines against polio. Both Salk and Sabin vaccines are indeed vaccines specifically developed to prevent polio. The Salk vaccine is an inactivated polio vaccine, while the Sabin vaccine is an oral live attenuated vaccine. Therefore, choice B is incorrect as the Sabin vaccine is live attenuated, not inactivated. Choice C is also incorrect because the Salk vaccine is inactivated, not live attenuated. Choice D is incorrect because not all statements are true; only statement A is accurate.

Correct Answer: D

Rationale: The correct answer is D: mixed infection. In a mixed infection, multiple infectious agents establish themselves at the same site, leading to a complex and diverse infection. This type of infection can involve different types of pathogens such as bacteria, viruses, fungi, and parasites. It can be challenging to diagnose and treat due to the presence of multiple pathogens. A: Chronic infection refers to an infection that persists over a long period but is typically caused by a single pathogen. B: Necrotizing infection is characterized by rapid tissue destruction but does not necessarily involve multiple infectious agents. C: Fatal infection does not specify the presence of multiple infectious agents, it simply implies that the infection leads to death. In summary, the correct answer, mixed infection, is the only choice that specifically describes the scenario of multiple infectious agents establishing themselves at the same site.