Nokea
What is the role of macrophages in granuloma formation?
- A. Neutralizing histamine
- B. Engulfing antigens but failing to destroy them
- C. Stimulating IgE production
- D. Producing antibodies against antigens
Correct Answer: B
Rationale: The correct answer is B because macrophages play a crucial role in granuloma formation by engulfing antigens but failing to destroy them, leading to the formation of a cluster of immune cells to contain the persistent antigen. Macrophages present antigens to T cells, triggering an immune response. Other choices are incorrect as macrophages do not neutralize histamine, stimulate IgE production, or produce antibodies against antigens in the context of granuloma formation.
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Mutations in which of the following genes are considered a risk factor for Crohn's disease?
- A. TLR-4
- B. NOD2
- C. NADPH oxidase
- D. IL-2
Correct Answer: B
Rationale: The correct answer is B: NOD2. Mutations in the NOD2 gene have been strongly associated with an increased risk of Crohn's disease. NOD2 is involved in the immune response to bacteria in the gut, and mutations in this gene can lead to dysregulation of the immune system, contributing to the development of Crohn's disease.
A: TLR-4 is involved in the recognition of bacterial components but mutations in this gene are not strongly linked to Crohn's disease.
C: NADPH oxidase is important for the production of reactive oxygen species in immune cells but mutations in this gene are not known to be a risk factor for Crohn's disease.
D: IL-2 is a cytokine involved in immune regulation but mutations in this gene are not associated with an increased risk of Crohn's disease.
Which scientist is credited with introducing the germ theory of disease?
- A. Louis Pasteur
- B. Edward Jenner
- C. Elie Metchnikoff
- D. Paul Ehrlich
Correct Answer: A
Rationale: Louis Pasteur is credited with introducing the germ theory of disease. He conducted experiments that demonstrated the role of microorganisms in causing infections. He also developed pasteurization to kill harmful bacteria in food and beverages. Edward Jenner is known for developing the smallpox vaccine, not the germ theory. Elie Metchnikoff studied the immune system and phagocytosis. Paul Ehrlich is known for his work on chemotherapy and the concept of the "magic bullet," targeting specific pathogens.
Agricultural uses of plant hormones include
- A. Control of fruit production, ripening, and dropping
- B. Production of seedless fruits
- C. Use as weed killers
- D. All above
Correct Answer: D
Rationale: The correct answer is D because plant hormones are used in agriculture to control fruit production, ripening, dropping, and to produce seedless fruits. Choice A is correct as plant hormones regulate these processes. Choice B is also correct as certain plant hormones can induce seedless fruit formation. Choice C is incorrect as plant hormones are not typically used as weed killers in agriculture. Overall, the correct answer, D, encompasses all the agricultural uses of plant hormones listed in the other choices.
Which of the statements below is NOT true. Integration is a stage of HIV life cycle that
- A. Utilizes a host enzyme called integrase
- B. Is a target of some anti-HIV drugs
- C. Allows duplication of proviral DNA when the infected cell divides
- D. Requires the formation of double stranded DNA
Correct Answer: A
Rationale: The correct answer is A. Integration is a stage of HIV life cycle that involves the insertion of viral DNA into the host cell's genome, facilitated by the enzyme integrase. To explain why A is incorrect, integrase is a viral enzyme, not a host enzyme.
B is correct as some anti-HIV drugs target the integration stage to prevent viral replication.
C is correct as integrated proviral DNA allows for duplication during cell division.
D is correct as integration requires the formation of double-stranded viral DNA.
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.