Nokea
Which cells are involved in innate immunity?
- A. B lymphocytes
- B. T lymphocytes
- C. Natural killer cells
- D. Plasma cells
Correct Answer: C
Rationale: The correct answer is C: Natural killer cells. Natural killer cells are part of the innate immune system and play a crucial role in identifying and destroying infected or abnormal cells. They are able to recognize and target cells that lack specific markers, providing a rapid response to infections.
Explanation for incorrect choices:
A: B lymphocytes are part of the adaptive immune system, not innate immunity.
B: T lymphocytes are also part of the adaptive immune system, not involved in innate immunity.
D: Plasma cells are differentiated B cells that produce antibodies in the adaptive immune response, not part of innate immunity.
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The annotation B refers to which DNA component?
- A. Recombinant DNA
- B. Plasmid DNA
- C. Vector DNA
- D. Insert DNA
Correct Answer: C
Rationale: The correct answer is C: Vector DNA. In genetic engineering, a vector is a DNA molecule used to carry foreign genetic material into another cell. Plasmid DNA (choice B) is a type of vector, but not all vectors are plasmids. Recombinant DNA (choice A) refers to DNA that has been artificially created by combining DNA from different sources. Insert DNA (choice D) is the foreign genetic material that is inserted into a vector. Therefore, the most specific and accurate choice is C, Vector DNA, as it encompasses all types of vectors used in genetic engineering.
Phagocytes were discovered by:
- A. Ilya Metchnikoff
- B. Louis Pasteur
- C. Emil von Behring
- D. Robert Koch
Correct Answer: A
Rationale: The correct answer is A: Ilya Metchnikoff. He discovered phagocytes through his research on immune responses in starfish larvae. Metchnikoff observed cells engulfing foreign particles, leading to the discovery of phagocytosis. Louis Pasteur is famous for his work in microbiology and vaccination. Emil von Behring discovered antitoxins. Robert Koch is known for his work in bacteriology and identifying the causative agents of diseases. Therefore, the correct answer is A as Metchnikoff specifically discovered phagocytes.
Which immunoglobulins will initially protect a newborn baby of a breastfeeding mother (select all that apply)?
- A. IgA
- B. IgD
- C. IgE
- D. IgG
Correct Answer: A
Rationale: IgA is transferred through breast milk and provides mucosal immunity, while IgG crosses the placenta during pregnancy to provide systemic protection.
EcoRI restriction endonuclease reactions produce fragments with
- A. 3' cohesive ends
- B. blunt ends
- C. 5' cohesive ends
- D. none of the options are correct
Correct Answer: C
Rationale: EcoRI recognizes the palindromic sequence GAATTC and cuts between G and A on both strands, producing 5' cohesive ends. Cohesive ends can base-pair with complementary ends, facilitating DNA ligation. Blunt ends (choice B) are produced by enzymes that cut both DNA strands at the same position. Choice A is incorrect as EcoRI produces 5' cohesive ends, not 3' cohesive ends. Choice D is incorrect as EcoRI does produce cohesive ends.
Which of the following is a physical barrier provided by innate immunity?
- A. Antibodies
- B. T lymphocytes
- C. Tight junctions in epithelial cells
- D. Phagocytosis
Correct Answer: C
Rationale: The correct answer is C: Tight junctions in epithelial cells. These junctions physically prevent pathogens from entering the body. Antibodies (A) and T lymphocytes (B) are components of adaptive immunity, not physical barriers. Phagocytosis (D) is a cellular process, not a physical barrier.