Nokea
What does the mechanism of chemotaxis accomplish?
- A. Causes the transformation of monocytes into macrophages
- B. Involves a pathway of chemical processes resulting in cellular lysis
- C. Attracts the accumulation of neutrophils and monocytes to an area of injury
- D. Slows the blood flow in a damaged area, allowing migration of leukocytes into tissue
Correct Answer: C
Rationale: Chemotaxis is the process by which immune cells such as neutrophils and monocytes are attracted to the site of injury or infection through chemical signals. These signals guide the cells to areas where they are needed most.
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Hfr strains of bacteria:
- A. do not have an 'F' (fertility) factor.
- B. have an 'F' factor plasmid.
- C. have an 'F' factor integrated in the bacterial chromosome.
- D. transfer the genetic information to other bacteria with ow frequency.
Correct Answer: C
Rationale: The correct answer is C because Hfr strains of bacteria have the F factor integrated into their bacterial chromosome. This integration allows for the transfer of genetic material during conjugation. This integration results in a high frequency of genetic information transfer to recipient cells, which is a characteristic of Hfr strains.
Choice A is incorrect because Hfr strains do have the F factor, but it is integrated into their chromosome, not absent. Choice B is incorrect because Hfr strains do not just have an F factor plasmid; it is integrated into the chromosome. Choice D is incorrect because Hfr strains actually transfer genetic information with high frequency, not low frequency.
The rearrangement of B cell antigen receptor genes occurs in
- A. Germinal centres
- B. Cortical areas of lymph nodes
- C. Bone marrow
- D. All secondary lymphoid organs
Correct Answer: C
Rationale: The rearrangement of B cell antigen receptor genes occurs in the bone marrow. This process involves the assembly of variable (V), diversity (D), and joining (J) gene segments to generate a diverse repertoire of B cell receptors. The bone marrow provides the necessary environment for this gene rearrangement to take place, ensuring the development of functional B cells. Germinal centers and cortical areas of lymph nodes are involved in B cell activation and differentiation, not gene rearrangement. While secondary lymphoid organs support B cell activation and immune responses, they are not specifically where the gene rearrangement occurs.
Peyer's patches are found in the:
- A. Intestine
- B. Spleen
- C. Lungs
- D. Skin
Correct Answer: A
Rationale: Peyer's patches are lymphoid nodules located in the small intestine, specifically in the ileum. They play a crucial role in the immune response of the gut. The correct answer is A: Intestine because Peyer's patches are specifically found in the intestine. The other choices are incorrect because the spleen is a different organ involved in filtering blood, the lungs are primarily involved in respiration, and the skin is the body's largest organ responsible for protection and thermoregulation.
Flu neuraminidase is
- A. A protein that allows the virus to escape the host immune response
- B. A surface protein that allows the release of newly formed viral particles
- C. The target of Tamiflu
- D. Both B and C are correct
Correct Answer: D
Rationale: The correct answer is D because flu neuraminidase is a surface protein that allows the release of newly formed viral particles and it is also the target of Tamiflu. Neuraminidase helps the virus spread by cleaving sialic acid from host cells, facilitating the release of viral particles. Tamiflu inhibits neuraminidase, preventing the spread of the virus. Option A is incorrect because neuraminidase does not directly help the virus escape the host immune response. Option B is partially correct but incomplete without mentioning Tamiflu. Option C is also partially correct but incomplete without mentioning the role of neuraminidase in releasing viral particles.
An older adult has fallen and sprained his ankle in a local park. Which action should the responder perform first?
- A. Elevate the foot.
- B. Apply ice.
- C. Administer aspirin.
- D. Assist the patient with ambulation.
Correct Answer: A
Rationale: The correct action is to elevate the foot first. Elevating the foot helps reduce swelling and pain by promoting better circulation. This step is crucial in the initial management of a sprained ankle. Applying ice and administering aspirin can come after elevating the foot. Assisting with ambulation should only be considered after the initial measures are taken to address the sprained ankle.