openstax microbiology test bank

Correct Answer: D

Rationale: The correct answer is D. Sepsis is a systemic response to infection resulting in organ dysfunction. A: Sepsis can be caused by bacterial infection, but it is not solely defined by the presence of bacteria in the blood. B: Bacteremia is the presence of bacteria in the blood, which can be a component of sepsis, but sepsis involves a broader systemic response beyond just bacteremia. C: Sepsis can lead to the release of toxins and organ failure, but sepsis itself is not defined solely by the massive proliferation of toxins. Therefore, the correct answer is D, as sepsis can involve the presence of bacteria, bacteremia, systemic manifestations, and organ failure.

Correct Answer: A

Rationale: The correct answer is A: Anaerobic. Pulpitis is an inflammatory condition of the dental pulp, often caused by bacterial infection. Anaerobic bacteria are commonly associated with dental infections, making it likely to find them in the inoculated culture medium. Anaerobic bacteria thrive in the absence of oxygen, which is typical of the dental environment. Acid-resistant (B) and acidophilic (C) microorganisms are not specifically linked to pulpitis. Haemolytic (D) microorganisms typically lyse red blood cells, which is not a characteristic feature of bacteria causing pulpitis. Therefore, the most likely microorganisms to be found in the culture medium would be anaerobic bacteria.

Correct Answer: B

Rationale: The correct answer is B: placenta. The placenta is a highly specialized structure that forms during pregnancy and serves as a barrier, protecting the fetus from harmful microorganisms that could potentially harm the developing baby. It facilitates the exchange of nutrients, oxygen, and waste between the mother and fetus while preventing the passage of most bacteria and viruses. The uterus (A) is the organ where the fetus develops, but it does not have the specific protective functions of the placenta. The vagina (C) is the birth canal and does not provide protection from microorganisms for the fetus. The mammary gland (D) is responsible for producing milk after birth and is not directly involved in protecting the fetus from microorganisms during pregnancy.

Correct Answer: C

Rationale: The correct answer is C: Binding of mast cell-fixed IgE. The Bezredka method involves introducing small amounts of the antigen to which the individual is allergic, leading to the binding of mast cell-fixed IgE. This process desensitizes the immune system and prevents anaphylactic shock by reducing the release of histamine and other mediators from mast cells. Rationale: 1. A: Stimulation of antigen-specific IgG2 is incorrect because the Bezredka method primarily targets IgE, not IgG2. 2. B: Stimulation of the immunological antigen tolerance is incorrect as this method aims to block the allergic response rather than induce tolerance. 3. D: Blocking of mast cell mediators synthesis is incorrect because the Bezredka method does not directly inhibit the synthesis of mast cell mediators, but rather blocks their release by binding IgE.

Correct Answer: D

Rationale: Interferon is a cell-specific protein that is produced and released from infected cells in response to viral infections. It acts extracellularly to interfere with viral replication, not to inactivate the virus itself. Interferon is not coded for by cellular DNA, but by viral RNA during infection. Therefore, the correct answer, D, is that interferon is not virus-specific but is cell-specific. This is because interferon can be produced by various cell types in response to different types of viral infections, making it a broad-spectrum antiviral defense mechanism.