Nokea
A major antibody-mediated mechanism of defense against parasitic worms involves:
- A. Neutrophil degranulation
- B. Opsonization
- C. Triggering of physiological responses (such as coughing) that expel the worm
- D. Neutralization by IgE along the mucosal surface of the gut
Correct Answer: D
Rationale: The correct answer is D because neutralization by IgE along the mucosal surface of the gut is a major antibody-mediated mechanism against parasitic worms. IgE binds to antigens on the worm's surface, leading to the release of histamine and other mediators that help expel the worm. Neutrophil degranulation (A) is more associated with bacterial infections, opsonization (B) is mainly for phagocytosis of pathogens, and triggering physiological responses (C) is not a direct antibody-mediated defense against parasitic worms.
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NAD and FAD are hydrogen carriers, but cytochromes are electron carriers in bacteria. What happens to the protons (Hâº) in electron transport chains?
- A. They go into solution inside the cytoplasm.
- B. They are taken back by NAD and FAD.
- C. They are carried from cytochromes to oxygen to form water.
- D. They go into solution outside the cytoplasmic membrane.
Correct Answer: D
Rationale: The correct answer is D because in the electron transport chain, protons (H⁺) are pumped across the membrane to create a proton gradient. This gradient is utilized by ATP synthase to produce ATP. Therefore, protons go into solution outside the cytoplasmic membrane. Choices A and B are incorrect because protons do not simply stay in the cytoplasm or get taken back by NAD and FAD. Choice C is incorrect as protons do not directly form water when carried by cytochromes.
Which of the following is a feature of antigen recognition by B cells?
- A. Their antigen receptors are never secreted
- B. Their antigen receptors recognize a fragment of protein in combination with an MHC molecule
- C. Their receptors each have two identical antigen binding sites
- D. They recognize pattern associated molecular structures (PAMPs) that are unique to a particular pathogen
Correct Answer: C
Rationale: The correct answer is C because B cell receptors, known as antibodies, are Y-shaped proteins with two identical antigen-binding sites. This feature allows B cells to bind to specific antigens with high specificity. Each B cell receptor can bind to a unique antigen, leading to the initiation of an immune response.
Choice A is incorrect because B cell receptors can be secreted as antibodies to target antigens outside the cell.
Choice B is incorrect because B cell receptors recognize antigens directly, not in combination with MHC molecules.
Choice D is incorrect because B cells primarily recognize specific antigens rather than general PAMPs associated with pathogens.
Which of the following statements is NOT true?
- A. Plague or Black Death is the disease that devastated Europe in Medieval times (1350-1400) with about 50% of the European population having been wiped out.
- B. There are reports of Black Death dating as early as 1000 B.C. making plague probably the most ancient disease and the first recorded
- C. Plague is still endemic in some countries
- D. Plague can be cured with antibiotics
Correct Answer: B
Rationale: The correct answer is B because there are no reports of the Black Death dating back to 1000 B.C. The Black Death specifically refers to the pandemic outbreak of the bubonic plague in the 14th century. The first recorded pandemic of the Black Death occurred in the 14th century, not in 1000 B.C. The other choices are incorrect because A is true as the Black Death did devastate Europe in the 14th century, C is true as plague is still present in some countries, and D is true as plague can be treated with antibiotics if caught early.
Which of the following white blood cells is small,present in blood and migrates to tissue as necessary?
- A. Neutrophils
- B. Leukocytes
- C. Monocytes
- D. Lymphocytes
Correct Answer: D
Rationale: Lymphocytes are small white blood cells that circulate in the blood and migrate to tissues as needed to participate in immune responses.
A good vaccine will:
- A. Be highly pathogenic
- B. Be highly immunogenic
- C. Induce herd immunity in a vaccinated individual
- D. All of the above
Correct Answer: B
Rationale: The correct answer is B: Be highly immunogenic. A good vaccine should effectively stimulate the immune system to produce a strong immune response against the targeted pathogen while being safe for the individual. This is crucial for developing immunity without causing harm.
Choice A (Be highly pathogenic) is incorrect because a vaccine should not cause disease or harm to the individual receiving it. Choice C (Induce herd immunity in a vaccinated individual) is also incorrect as herd immunity refers to protection of a population, not an individual.
In summary, a good vaccine should be highly immunogenic to effectively trigger an immune response without causing harm, leading to protection against the targeted pathogen.