Nokea
What structure is recognized by TLR4 in mammals?
- A. Peptidoglycan
- B. Lipopolysaccharide (LPS)
- C. Double-stranded RNA
- D. Mannose-binding lectin
Correct Answer: B
Rationale: The correct answer is B: Lipopolysaccharide (LPS). TLR4 recognizes LPS, a component of the outer membrane of Gram-negative bacteria, triggering an immune response. This recognition is crucial in detecting bacterial infections. Peptidoglycan (A) is recognized by other TLRs, not TLR4. Double-stranded RNA (C) is recognized by TLR3, not TLR4. Mannose-binding lectin (D) is a pattern recognition receptor that binds to carbohydrate structures, not specifically recognized by TLR4.
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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.
How do cytokines typically function in the body?
- A. In an endocrine manner
- B. In an autocrine and paracrine manner
- C. Solely by direct contact with pathogens
- D. By degrading immune cells
Correct Answer: B
Rationale: The correct answer is B because cytokines primarily function in an autocrine and paracrine manner. Autocrine signaling occurs when a cell produces a cytokine that acts on the same cell, while paracrine signaling involves cytokines acting on nearby cells. This allows cytokines to regulate immune responses locally. Option A is incorrect as endocrine signaling involves hormones acting on distant target cells via the bloodstream, which is not the primary function of cytokines. Option C is incorrect because cytokines do not require direct contact with pathogens to function. Option D is incorrect as cytokines do not degrade immune cells but rather regulate immune responses.
Identify the correct statement(s). In eukaryotic microorganisms:
- A. mRNA is short-lived (minutes).
- B. a single, circular chromosome is present.
- C. 5s, 16s, and 23s ribosomal RNA's are present.
- D. extrachromosomal DNA can be present.
Correct Answer: D
Rationale: The correct answer is D because extrachromosomal DNA, such as plasmids, can be present in eukaryotic microorganisms. This is true for certain organisms like yeast and some fungi. These DNA molecules are separate from the main chromosomal DNA and can carry additional genetic information.
A: mRNA in eukaryotic microorganisms is not short-lived; it can have varying lifespans depending on the specific mRNA molecule and cellular conditions.
B: Eukaryotic microorganisms typically have multiple linear chromosomes, not a single circular chromosome.
C: While 5s, 16s, and 23s ribosomal RNAs are present in prokaryotic organisms, eukaryotic microorganisms have different types of ribosomal RNA subunits.
What is the normal pH range of the blood and what ratio of base to acid does this reflect?
- A. 7.32 to 7.42; 25 to 2
- B. 7.32 to 7.42; 28 to 2
- C. 7.35 to 7.45; 20 to 1
- D. 7.35 to 7.45; 30 to 1
Correct Answer: C
Rationale: The normal blood pH range is 7.35–7.45, reflecting a bicarbonate-to-carbonic acid ratio of approximately 20:1.
The nurse is caring for a patient being tested for rheumatoid arthritis. In reviewing laboratory values, which should the nurse recognize as being diagnostic of rheumatoid arthritis?
- A. C-reactive protein = 12 mg/L
- B. Rheumatoid factor is negative.
- C. White blood cells = 6000/mm3
- D. Antinuclear antibody test is negative.
Correct Answer: A
Rationale: The correct answer is A because an elevated C-reactive protein level indicates inflammation, which is a key feature of rheumatoid arthritis. Rheumatoid factor (choice B) is positive in only 70-80% of patients with rheumatoid arthritis, so a negative result does not rule out the disease. White blood cell count (choice C) and antinuclear antibody test (choice D) are not specific to rheumatoid arthritis. In summary, an elevated C-reactive protein level is a more reliable indicator of the disease compared to the other options provided.