Nokea
The nurse is counseling a group of individuals over the age of 50 with average risk for cancer about screening tests for cancer. Which screening recommendation should be performed to screen for colorectal cancer?
- A. Barium enema every year
- B. Colonoscopy every 10 years
- C. Fecal occult blood every 5 years
- D. Annual prostate-specific antigen (PSA) and digital rectal exam
Correct Answer: B
Rationale: Colonoscopy every 10 years is recommended for colorectal cancer screening in individuals over 50 with average risk.
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What is the structural composition of an antibody?
- A. Two heavy chains and two light chains
- B. Three heavy chains and one light chain
- C. Two heavy chains and three light chains
- D. Four heavy chains
Correct Answer: A
Rationale: The correct answer is A: Two heavy chains and two light chains. Antibodies are composed of two identical heavy chains and two identical light chains. Heavy chains provide structural support and effector functions, while light chains contribute to antigen binding. Choice B is incorrect as antibodies do not have three heavy chains. Choice C is incorrect as antibodies do not have three light chains. Choice D is incorrect as antibodies do not have four heavy chains.
What is a defining characteristic of immunology as a scientific field?
- A. It is largely static, with few modern discoveries
- B. It is a dynamic field, continually evolving through research
- C. It exclusively studies pathogen biology
- D. It focuses solely on innate immunity
Correct Answer: B
Rationale: The correct answer is B: It is a dynamic field, continually evolving through research. Immunology is constantly evolving due to new discoveries and advancements in technology. Research in immunology leads to a deeper understanding of the immune system and its interactions with pathogens, cancer, and other diseases. This ongoing evolution is essential for the development of new treatments and vaccines.
Explanation of why other choices are incorrect:
A: It is largely static, with few modern discoveries - This is incorrect as immunology is a rapidly advancing field with numerous breakthroughs and discoveries.
C: It exclusively studies pathogen biology - This is incorrect as immunology also encompasses the study of the immune system's responses to various stimuli, not just pathogens.
D: It focuses solely on innate immunity - This is incorrect as immunology covers both innate and adaptive immunity, as well as the interactions between them.
What distinguishes Type V hypersensitivity from Type II?
- A. It is mediated by T cells
- B. Antibodies stimulate receptors instead of destroying them
- C. It involves immune complex formation
- D. It does not involve the immune system
Correct Answer: B
Rationale: The correct answer is B because Type V hypersensitivity involves antibodies stimulating receptors instead of destroying them. In Type II hypersensitivity, antibodies target antigens on cell surfaces, leading to cell destruction. In Type V, antibodies bind to cell receptors, causing abnormal receptor activation. Choices A, C, and D are incorrect because Type V hypersensitivity is not mediated by T cells (A), does not involve immune complex formation (C), and does involve the immune system (D). Therefore, the unique characteristic of Type V hypersensitivity is the stimulation of receptors by antibodies, making choice B the correct answer.
Why is plasmapheresis indicated in the treatment of autoimmune disorders?
- A. Obtain plasma for analysis and evaluation of specific autoantibodies
- B. Decrease high lymphocyte levels in the blood to prevent immune responses
- C. Remove autoantibodies, antigen-antibody complexes, and inflammatory mediators of immune reactions
- D. Add monocytes to the blood to promote removal of immune complexes by the mononuclear phagocyte system
Correct Answer: C
Rationale: Plasmapheresis removes harmful autoantibodies, immune complexes, and inflammatory mediators from the bloodstream.
Which of the following DNA polymerases cleaves a DNA sequence at the direction of 5' → 3'?
- A. DNA polymerase I
- B. DNA polymerase II
- C. DNA polymerase III
- D. DNA polymerase IV
Correct Answer: A
Rationale: The correct answer is A: DNA polymerase I. DNA polymerase I has both 5' to 3' polymerase activity and 5' to 3' exonuclease activity, allowing it to cleave DNA in the 5' to 3' direction. This enzyme can remove RNA primers during DNA replication by cleaving them in the 5' to 3' direction and replace them with DNA nucleotides. DNA polymerase II, III, and IV do not have the same exonuclease activity as DNA polymerase I, so they are not capable of cleaving DNA sequences in the 5' to 3' direction like DNA polymerase I.