Nokea
Molecules that are considered members of the 'immunoglobulin superfamily':
- A. Contain one or more protein domains with a compact barrel structure
- B. Are always lymphocyte antigen receptors
- C. Are highly unstable relative to other proteins
- D. All of the above
Correct Answer: A
Rationale: The correct answer is A because molecules in the immunoglobulin superfamily typically contain one or more protein domains with a compact barrel structure. This structure is characteristic of immunoglobulin-like domains found in proteins involved in immune responses. Choice B is incorrect because not all members of the immunoglobulin superfamily are lymphocyte antigen receptors. Choice C is incorrect as these molecules are not necessarily highly unstable compared to other proteins. Therefore, the correct answer is A as it accurately describes a common structural feature of molecules in the immunoglobulin superfamily.
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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.
Although the cause of autoimmune disorders is unknown, which factors are believed to be present in most conditions (select all that apply)?
- A. Younger age
- B. Male gender
- C. Inheritance of susceptibility genes
- D. Initiation of autoreactivity by triggers
Correct Answer: C
Rationale: Autoimmune disorders are often associated with genetic predisposition and environmental triggers that initiate autoreactivity.
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.
To raise antibodies that interfere with the interaction of HIV with CD4+ T cells, vaccines should target which of the following HIV antigens
- A. gp41
- B. Reverse transcriptase
- C. gp120
- D. Matrix proteins
Correct Answer: C
Rationale: The correct answer is C: gp120. This is because gp120 is a key HIV antigen that plays a crucial role in binding to CD4 receptors on T cells, facilitating viral entry. By targeting gp120, vaccines can induce antibodies that block this interaction, preventing HIV from infecting CD4+ T cells. Conversely, choices A, B, and D (gp41, Reverse transcriptase, Matrix proteins) are not as effective targets for interfering with the CD4+ T cell interaction, as they do not directly impact the initial binding and entry process of HIV into the cells.
A cell whose functions include ingesting foreign or invading cells is a (an):
- A. T cell.
- B. B cell.
- C. Macrophage.
- D. Erythrocyte.
Correct Answer: C
Rationale: Macrophages are specialized cells that engulf and digest pathogens, cellular debris, and other foreign substances. T cells and B cells play roles in adaptive immunity, while erythrocytes (red blood cells) are involved in oxygen transport.