Nokea
The site where B cells mature is
- A. Lymph nodes (LN)
- B. Spleen
- C. Bone marrow
- D. Thymus
Correct Answer: C
Rationale: The correct answer is C: Bone marrow. B cells undergo maturation in the bone marrow, where they develop from hematopoietic stem cells. This is where they acquire their antigen receptors and differentiate into mature B cells. Lymph nodes (A) are primarily responsible for filtering lymph and containing immune cells. The spleen (B) is involved in filtering blood and storing immune cells. The thymus (D) is where T cells mature, not B cells. Therefore, the correct site for B cell maturation is the bone marrow.
You may also like to solve these questions
The nurse realizes that the patient understands the teaching about decreasing the risk for antibiotic-resistant infection when the patient says which of the following?
- A. I know I should take the antibiotic for one day after I feel better.
- B. I want an antibiotic ordered for my cold so I can feel better sooner.
- C. I always save some pills because I get the illness again after I first feel better.
- D. I will follow the directions for taking the antibiotic so I will get over this infection.
Correct Answer: D
Rationale: Following the prescribed regimen ensures complete eradication of the infection and reduces the risk of resistance development.
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 condition is caused by a Type IV hypersensitivity reaction?
- A. Anaphylaxis
- B. Sarcoidosis
- C. Grave's disease
- D. Goodpasture's syndrome
Correct Answer: B
Rationale: The correct answer is B: Sarcoidosis. Type IV hypersensitivity reactions are mediated by T cells and are characterized by delayed onset inflammatory responses. Sarcoidosis is a granulomatous disease where T cells form granulomas in affected tissues. Anaphylaxis (A) is a Type I hypersensitivity reaction involving IgE antibodies. Grave's disease (C) is an autoimmune disorder caused by Type II hypersensitivity reaction mediated by antibodies. Goodpasture's syndrome (D) is a Type II hypersensitivity reaction involving antibodies attacking basement membranes. Therefore, the correct answer is B as it fits the characteristics of a Type IV hypersensitivity reaction.
Which part of an antibody determines its antigen specificity?
- A. Fc fragment
- B. Fab region
- C. Heavy chain constant region
- D. Light chain constant region
Correct Answer: B
Rationale: The correct answer is B: Fab region. The Fab region of an antibody contains the antigen-binding site, where specific interactions with antigens occur. This region is formed by the variable regions of both the heavy and light chains. The Fc fragment (choice A) is responsible for effector functions, not antigen specificity. The heavy chain constant region (choice C) and light chain constant region (choice D) are not involved in antigen binding, but rather provide structural support and determine the antibody class. Therefore, the Fab region is crucial for antigen specificity due to its variable regions that directly interact with antigens.
Virulence factors can be transferred from pathogenic to non-pathogenic bacterial strains that are part of the normal flora. An example of a commensal bacterial species that has turned into a pathogenic strain is:
- A. E. coli 0157:H7
- B. M. tuberculosis
- C. Group A S. pyogenes
- D. All opportunistic bacterial species
Correct Answer: A
Rationale: The correct answer is A: E. coli 0157:H7. This strain of E. coli has acquired virulence factors that allow it to cause severe illness in humans, such as bloody diarrhea and kidney failure. The transformation of E. coli from a commensal to a pathogenic strain is well-documented. In contrast, choices B and C involve species that are inherently pathogenic and not commensal. Choice D is too broad and includes a wide range of bacterial species that do not necessarily originate from the normal flora. Therefore, E. coli 0157:H7 is the best example of a commensal bacterium that has turned pathogenic due to the acquisition of virulence factors.