microbiology an introduction 12th edition test bank

Correct Answer: A

Rationale: The correct answer is A because immunity in syphilis is nonsterile, meaning that individuals who have been infected may still carry the bacteria and be capable of transmitting the disease. This is due to the ability of the bacterium causing syphilis, Treponema pallidum, to evade the immune system by hiding within host cells. Option B, antitoxic, is incorrect because syphilis is not caused by a toxin produced by the bacteria, but rather by the bacterium itself. Option C, humoral, is also incorrect as syphilis immunity involves both humoral (antibody-mediated) and cell-mediated immune responses, not solely humoral immunity. Option D is incorrect as it includes all three options, whereas in reality, the immunity in syphilis is primarily nonsterile.

Correct Answer: A

Rationale: The correct answer is A: Triatomine bug. Triatomine bugs, also known as "kissing bugs," are the specific carrier of the trypanosomes that cause Chagas disease. These bugs transmit the parasite through their feces, which contain the infectious forms of the trypanosomes. When the bug bites a human or animal, it defecates near the bite wound, allowing the parasites to enter the bloodstream through the broken skin. Mosquitoes (B) transmit diseases like malaria and dengue fever, not Chagas disease. Tsetse flies (C) are known for transmitting African trypanosomiasis (sleeping sickness), not Chagas disease. Cockroaches (D) are not known to transmit Chagas disease.

Correct Answer: C

Rationale: Sterilization refers to the complete elimination of all microorganisms, including their spores, which are the most resistant form of microbial life. Spores have a tough outer coating that protects them from harsh conditions, making them more difficult to destroy compared to vegetative cells, viruses, and protozoa. Therefore, the correct answer is C because sterilization targets and eliminates all forms of microorganisms, including spores. Choices A, B, and D are incorrect because sterilization goes beyond just targeting vegetative cells, viruses, or protozoa; it aims to eliminate all microorganisms present.

Correct Answer: D

Rationale: The correct answer is D, Cholera. Cholera is caused by the bacterium Vibrio cholerae and primarily affects the intestines, leading to severe watery diarrhea and dehydration. It does not damage the respiratory tract. Choice A, Tularemia, affects the respiratory tract and other organs. Choice B, Plague, can cause respiratory symptoms like cough and difficulty breathing. Choice C, Anthrax, can affect the respiratory tract if inhaled in its spore form.

Correct Answer: C

Rationale: The correct answer is C: Respiratory tract. The respiratory tract is likely the most frequently used portal of entry for pathogens because it is constantly exposed to the external environment and has a large surface area lined with mucous membranes that can trap and facilitate the entry of pathogens. Additionally, the respiratory tract serves as a direct pathway for pathogens to reach the bloodstream and other organs. Skin (choice A) is a physical barrier that can prevent pathogen entry, while the gastrointestinal tract (choice B) has acidic pH and enzymes that can kill many pathogens. Conjunctiva (choice D) is a less common portal of entry compared to the respiratory tract due to its smaller surface area and protective mechanisms such as tears.