microbiology chapter 11 test bank

Correct Answer: B

Rationale: The correct answer is B: antitoxin. Antitoxin is the specific antidote to botulinum toxin as it helps neutralize the toxin in the body. Sodium bicarbonate (A) is used to treat acidosis, pralidoxime (C) is used for organophosphate poisoning, and naloxone (D) is used for opioid overdose. Antitoxin directly targets and counteracts the botulinum toxin, making it the appropriate antidote in cases of botulism.

Correct Answer: A

Rationale: The correct answer is A: IgG. Anti-tetanus gamma globulin is produced by hyperimmunization, leading to a high concentration of specific antibodies, predominantly IgG. IgG is the most abundant immunoglobulin in the blood and provides long-term immunity against tetanus. IgA is mainly found in mucosal areas, not in gamma globulin preparations. IgM is the first antibody produced in response to an infection and is not the prevailing class in this preparation. IgE is associated with allergic reactions and parasitic infections, not with anti-tetanus immunity.

Correct Answer: A

Rationale: Rationale for Correct Answer A (Lamblia): 1. Pyriform protozoa with twin nuclei, four pairs of flagella, and a suctorial disc match the characteristics of Giardia lamblia. 2. The presence of two supporting filaments between the nuclei is a unique feature of Giardia lamblia. 3. Giardia lamblia is known to infect the duodenum and cause symptoms such as diarrhea and abdominal pain. Summary of Incorrect Choices: B: Toxoplasma - Toxoplasma gondii is not characterized by four pairs of flagella or supporting filaments in the nuclei. C: Leishmania - Leishmania species do not typically have the described morphology or location in the duodenum. D: Intestinal trichomonad - Intestinal trichomonads do not exhibit the specific features mentioned in the question, such as twin nuclei and supporting filaments.

Correct Answer: C

Rationale: The correct answer is C because Leptospira cannot be cultivated on blood and chocolate agar. The bacterium requires specialized media such as Ellinghausen-McCullough-Johnson-Harris (EMJH) medium for growth. Blood and chocolate agar do not provide the necessary nutrients for the bacterium's growth. Leptospira is a fastidious organism that has unique culture requirements. Therefore, the statement that Leptospira can be cultivated on blood and chocolate agar is incorrect. The other choices are correct: A - Leptospirosis is an acute infectious disease with a typical geographic distribution, B - Reservoirs of leptospira are different wild and domestic animals, mainly rodents, and D - Doxycycline and penicillins are drugs of choice for the treatment of leptospirosis.

Correct Answer: B

Rationale: The correct answer is B: 3.5 to 4.0 billion years. Prokaryotic fossils date back to around 3.5 to 4.0 billion years ago, based on scientific evidence. This timeframe aligns with the earliest known evidence of life on Earth. Choices A, C, and D have incorrect timelines that do not correspond to the established age range of prokaryotic fossils. Choice A is too broad and includes a range that extends beyond the known fossil record. Choices C and D have much younger timelines, which do not match the historical evidence of prokaryotic life dating back billions of years.