Nokea
Which T cell type helps activate B cells?
- A. Cytotoxic T cells
- B. Helper T cells
- C. Regulatory T cells
- D. Memory T cells
Correct Answer: B
Rationale: The correct answer is B: Helper T cells. Helper T cells play a crucial role in activating B cells by releasing cytokines that stimulate B cell proliferation and differentiation into plasma cells, which produce antibodies. Cytotoxic T cells (A) are involved in directly killing infected cells. Regulatory T cells (C) suppress immune responses. Memory T cells (D) are responsible for maintaining immunological memory for future responses. Thus, Helper T cells are the key cell type that helps activate B cells.
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When comparing the types of viruses that infect bacteria, plants, and vertebrate animals, what trends appear from bacterial to vertebrate viral groups?
- A. Less complex-type forms
- B. more enveloped forms
- C. fewer enveloped forms
- D. same number of DNA-containing forms
Correct Answer: B
Rationale: The correct answer is B: more enveloped forms. This trend can be explained by the complexity of host organisms. Bacteria have simple cell structures, making enveloped viruses less common. As we move from bacteria to plants and vertebrate animals, the complexity of host cells increases, leading to a higher prevalence of enveloped viruses. This trend is due to the need for enveloped viruses to evade the host's immune system and facilitate entry into host cells. Choices A, C, and D are incorrect because they do not consider the relationship between virus structure and host complexity.
What is the prevalence of sarcoidosis in Ireland?
- A. One of the lowest globally
- B. Among the highest globally
- C. Similar to the global average
- D. Extremely rare
Correct Answer: B
Rationale: The correct answer is B: Among the highest globally. Sarcoidosis prevalence in Ireland is relatively high compared to other regions. This is due to genetic factors, environmental influences, and possibly healthcare practices. Sarcoidosis rates vary worldwide, with Ireland being noted for its higher prevalence. Choices A, C, and D are incorrect because Ireland's sarcoidosis prevalence is not among the lowest globally, similar to the global average, or extremely rare.
Which of the following represents the correct sequence of host immune defenses as encountered by a pathogen?
- A. Innate responses; physical barriers; adaptive responses
- B. Physical barriers; innate responses; adaptive responses
- C. Adaptive responses; physical barriers; innate responses
- D. Physical barriers; adaptive responses; innate responses
Correct Answer: B
Rationale: The correct sequence is B: Physical barriers; innate responses; adaptive responses. Physical barriers like skin and mucous membranes are the first line of defense, followed by innate responses (e.g., inflammation, phagocytosis) that provide immediate, non-specific protection. Adaptive responses (e.g., antibody production, T cell activation) are the final defense mechanism, specifically targeting the pathogen. Choices A, C, and D are incorrect because they do not follow the correct chronological order of how host immune defenses are encountered by a pathogen. Option A and D have the innate and adaptive responses in the wrong order, while option C places adaptive responses before physical barriers, which is not accurate in terms of the sequence of host immune defenses.
A segment of DNA that reads the same from forward and backward is called_____.
- A. Complementary DNA
- B. Palindromic DNA
- C. Copy DNA
- D. Transcribed DNA
Correct Answer: B
Rationale: The correct answer is B: Palindromic DNA. Palindromic DNA refers to a segment of DNA that reads the same from both directions. This property occurs when the nucleotide sequence on one strand of DNA is the reverse complement of the nucleotide sequence on the other strand. This symmetry allows the DNA sequence to be read the same forward and backward.
Incorrect choices:
A: Complementary DNA - Complementary DNA refers to a synthesized DNA strand that is complementary to a given DNA sequence.
C: Copy DNA - Copy DNA is not a commonly used term in molecular biology.
D: Transcribed DNA - Transcribed DNA refers to DNA that has been converted into RNA through the process of transcription, not DNA that reads the same forward and backward.
The nurse is reinforcing teaching to a person being tested for HIV in a clinic. Which test should the nurse explain is done first in HIV testing?
- A. ELISA test
- B. Western blot test
- C. Viral load studies
- D. Rheumatoid factor test
Correct Answer: A
Rationale: The correct answer is A: ELISA test. The ELISA test is typically the initial screening test for HIV due to its high sensitivity in detecting HIV antibodies. It is cost-effective and quick. Western blot test is a confirmatory test used if ELISA is positive. Viral load studies monitor the progression of the disease but are not typically done first. Rheumatoid factor test is unrelated to HIV testing. Therefore, the ELISA test is the most appropriate initial step in HIV testing.