Nokea
Which of the following is NOT commonly associated with granulomatous hypersensitivity?
- A. Crohn's disease
- B. Sarcoidosis
- C. Systemic lupus erythematosus (SLE)
- D. Tuberculosis
Correct Answer: C
Rationale: Granulomatous hypersensitivity is characterized by the formation of granulomas in response to persistent antigen exposure. Systemic lupus erythematosus (SLE) is an autoimmune disease involving immune complex deposition and inflammation, not granuloma formation. Crohn's disease, sarcoidosis, and tuberculosis are commonly associated with granulomatous hypersensitivity due to their chronic inflammatory nature and granuloma formation in affected tissues. SLE does not typically present with granulomas, making it the correct answer.
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The basic structure of an antibody molecule is
- A. One light chain and one heavy chain that are covalently linked and form one antigen binding site
- B. Two identical heavy chains and two identical light chains that are covalently linked and form two antigen binding sites
- C. Two identical heavy chains and two identical light chains covalently linked to form one antigen binding site
- D. Two identical light chains that form the antigen binding site and two identical heavy chains that mediate the effector functions of antibodies
Correct Answer: B
Rationale: Rationale for Answer B:
1. Antibody structure consists of two identical heavy chains and two identical light chains.
2. These chains are covalently linked to form the Y-shaped structure of an antibody.
3. Each chain contributes to the formation of antigen-binding sites.
4. Therefore, two identical heavy chains and two identical light chains form two antigen-binding sites.
Summary of Incorrect Choices:
A: Incorrect because it describes only one antigen-binding site formed by one light chain and one heavy chain.
C: Incorrect because it describes one antigen-binding site formed by two identical heavy chains and two identical light chains.
D: Incorrect because it incorrectly describes the roles of light and heavy chains in antibody structure.
What is the medical term for an abnormal decrease in platelets?
- A. Leukopenia
- B. Thrombocytopenia
- C. Anemia
- D. Hemolysis
Correct Answer: B
Rationale: The correct answer is B: Thrombocytopenia, which refers to an abnormal decrease in platelets. Platelets are crucial for blood clotting. Leukopenia (A) is a decrease in white blood cells, not platelets. Anemia (C) is a decrease in red blood cells, not platelets. Hemolysis (D) is the breakdown of red blood cells, not related to platelet count. Therefore, B is the correct answer as it specifically addresses a decrease in platelet count, leading to potential bleeding issues.
What is the typical outcome of a C1q deficiency in the complement system?
- A. Enhanced inflammation
- B. Reduced phagocytosis
- C. Autoimmune diseases such as SLE
- D. Increased cancer risk
Correct Answer: C
Rationale: The correct answer is C: Autoimmune diseases such as SLE. C1q is essential for the classical pathway of the complement system, which plays a crucial role in clearing immune complexes. A deficiency in C1q can lead to impaired immune complex clearance, resulting in the development of autoimmune diseases like Systemic Lupus Erythematosus (SLE).
Choice A (Enhanced inflammation) is incorrect because a deficiency in C1q would actually lead to decreased inflammation due to impaired complement activation.
Choice B (Reduced phagocytosis) is incorrect because phagocytosis is primarily mediated by the alternative pathway of the complement system, not the classical pathway involving C1q.
Choice D (Increased cancer risk) is incorrect as C1q deficiency is not directly associated with an increased risk of cancer.
Following class of restriction endonucleases is commercially available and used in recombinant DNA technology:
- A. Class 1
- B. Class 2
- C. Class 3
- D. Class 5
Correct Answer: B
Rationale: The correct answer is B: Class 2. Class 2 restriction endonucleases are commonly used in recombinant DNA technology due to their specificity for recognizing short DNA sequences and cleaving within or near these sequences. They are commercially available, easy to use, and have well-defined recognition sites, making them ideal for molecular cloning applications.
Choice A (Class 1) is incorrect because Class 1 enzymes require both ATP and S-adenosyl methionine for activity, making them less practical for routine laboratory use.
Choice C (Class 3) is incorrect because Class 3 enzymes cleave DNA at two sites, potentially leading to unwanted DNA fragmentation in recombinant DNA technology.
Choice D (Class 5) is incorrect because Class 5 restriction enzymes do not exist in the classification system of restriction endonucleases.
You give an intradermal injection of allergen to a patient who is undergoing skin testing for allergies. A few minutes later,the patient complains about feeling anxious short of breath and dizzy. You notice that the patient has reddened blotches on the face and arms. All of these therapies are available on your emergency cart. Which action should you take first?
- A. Start oxygen at 4 L/min using a nasal cannula.
- B. Obtain IV access with a large-bore IV catheter.
- C. Administer epinephrine (Adrenalin) 0.3 mL subcutaneously.
- D. Give albuterol (Proventil) with a nebulizer.
Correct Answer: C
Rationale: The patient is showing signs of anaphylaxis,a life-threatening allergic reaction. The first priority is to administer epinephrine which acts quickly to reverse the symptoms by constricting blood vessels relaxing airway muscles and increasing heart rate. Oxygen and IV access are important but secondary to the immediate administration of epinephrine. Albuterol may be used for bronchospasm but is not the first-line treatment for anaphylaxis.