Nokea
A cell type capable of killing virus-infected cells that provides early protection against viral infection is
- A. Eosinophils
- B. NK cells
- C. Neutrophils
- D. Mast cells
Correct Answer: B
Rationale: The correct answer is B: NK cells. NK cells are part of the innate immune system and can directly kill virus-infected cells, providing early protection against viral infections. They do not require prior exposure to the virus to initiate their killing mechanism, making them crucial for early defense. Eosinophils (A), Neutrophils (C), and Mast cells (D) are not primarily involved in killing virus-infected cells. Eosinophils are more associated with parasitic infections, Neutrophils are primarily involved in bacterial infections, and Mast cells are involved in allergic reactions.
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What is the diversity of pattern recognition receptors (PRRs) like?
- A. Highly diverse due to somatic recombination
- B. Limited because they are germline-encoded
- C. Constantly changing in response to infections
- D. Specific to individual antigens
Correct Answer: B
Rationale: The correct answer is B because pattern recognition receptors (PRRs) are encoded in the germline, meaning they are genetically determined and do not change during an individual's lifetime. This ensures consistency in detecting various pathogens across different individuals. Choices A, C, and D are incorrect because PRR diversity is not influenced by somatic recombination, does not change constantly in response to infections, and is not specific to individual antigens.
What is the medical term for excessive bleeding?
- A. Thrombosis
- B. Embolus
- C. Hemorrhage
- D. Hemostasis
Correct Answer: C
Rationale: The correct answer is C: Hemorrhage. Hemorrhage refers to excessive bleeding. Thrombosis (A) is the formation of blood clots, not excessive bleeding. Embolus (B) is a blood clot that travels through the bloodstream and blocks a blood vessel. Hemostasis (D) is the process of stopping bleeding, not the term for excessive bleeding. In summary, only choice C directly relates to the medical term for excessive bleeding.
Viral antigenic shift
- A. Is caused by multiple random mutations
- B. Is caused by a single mutation
- C. It affects only internal viral proteins not recognized by preexisting antibodies
- D. It refers to the appearance of new HA variants not recognized by preexisting antibodies
Correct Answer: D
Rationale: Step 1: Viral antigenic shift involves major changes in the surface proteins of the virus, particularly the hemagglutinin (HA) protein.
Step 2: These changes result in the emergence of new variants that are not recognized by preexisting antibodies.
Step 3: This process is distinct from antigenic drift, which involves minor changes due to random mutations.
Step 4: Choice D correctly states that viral antigenic shift refers to the appearance of new HA variants not recognized by preexisting antibodies.
Summary: Choice A is incorrect because viral antigenic shift is not caused by multiple random mutations. Choice B is incorrect as antigenic shift involves major changes, not a single mutation. Choice C is incorrect as it affects surface proteins like HA, not just internal proteins.
Which of the following statements accurately describe genetic testing (select all that apply)?
- A. Results of genetic testing may raise psychologic and emotional issues.
- B. An ethical issue that is raised with genetic testing is protection of privacy to prevent discrimination.
- C. Genetic testing of the mother can be used to determine an unborn child’s risk of having genetic conditions.
- D. An example of genetic testing that is required by all states is premarital testing of women for the hemophilia gene.
Correct Answer: B
Rationale: Genetic testing raises psychological and ethical concerns, helps assess risks in unborn children, and includes tests like BRCA1/BRCA2 mutation screening. Premarital hemophilia testing is not universally mandated.
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.