Nokea
Which T cell type is involved in directly killing infected or foreign cells?
- A. Helper T cells
- B. Cytotoxic T cells
- C. Regulatory T cells
- D. Memory T cells
Correct Answer: B
Rationale: The correct answer is B: Cytotoxic T cells. Cytotoxic T cells are responsible for directly killing infected or foreign cells by releasing toxic substances that induce apoptosis in the target cells. This process helps eliminate the threats to the body.
Helper T cells (Choice A) assist in coordinating immune responses but do not directly kill cells. Regulatory T cells (Choice C) play a role in suppressing immune responses to prevent autoimmunity but do not kill infected cells. Memory T cells (Choice D) are primed for rapid response upon re-exposure to a specific antigen but do not directly kill cells. Therefore, the correct choice is B as cytotoxic T cells are specifically designed for cell killing.
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What disease is associated with autoantibodies binding to type IV collagen?
- A. Sarcoidosis
- B. Goodpasture's syndrome
- C. Systemic lupus erythematosus (SLE)
- D. Rheumatoid arthritis
Correct Answer: B
Rationale: The correct answer is B: Goodpasture's syndrome. This disease is specifically associated with autoantibodies targeting type IV collagen in the basement membranes of the kidneys and lungs, leading to glomerulonephritis and pulmonary hemorrhage. Sarcoidosis (A) involves non-caseating granulomas, not collagen autoantibodies. Systemic lupus erythematosus (SLE) (C) is associated with various autoantibodies but not specifically targeting type IV collagen. Rheumatoid arthritis (D) is characterized by autoantibodies against citrullinated peptides and synovial tissue, not type IV collagen.
Which normal tissues manifest early, acute responses to radiation therapy?
- A. Spleen and liver
- B. Kidney and nervous tissue
- C. Bone marrow and gastrointestinal (GI) mucosa
- D. Hollow organs such as the stomach and bladder
Correct Answer: C
Rationale: Bone marrow and GI mucosa are highly sensitive to radiation and show early acute responses.
Amino acids are building blocks of
- A. Carbohydrates
- B. Nucleic acids
- C. Lipids
- D. Proteins
Correct Answer: D
Rationale: The correct answer is D: Proteins. Amino acids are the building blocks of proteins because they are linked together in a specific sequence to form protein chains. Proteins are essential for various biological functions in the body.
Incorrect options:
A: Carbohydrates - Carbohydrates are made up of sugar molecules, not amino acids.
B: Nucleic acids - Nucleic acids, like DNA and RNA, are made up of nucleotides, not amino acids.
C: Lipids - Lipids are composed of fatty acids and glycerol, not amino acids.
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.
What is the key immune cell involved in granuloma formation?
- A. Mast cells
- B. Macrophages
- C. Neutrophils
- D. Dendritic cells
Correct Answer: B
Rationale: The correct answer is B: Macrophages. Macrophages are key immune cells involved in granuloma formation. They play a crucial role in engulfing and processing pathogens or foreign particles, leading to the formation of granulomas as part of the body's immune response. Mast cells (A) are primarily involved in allergic reactions. Neutrophils (C) are important in the initial immune response to infections but are not typically associated with granuloma formation. Dendritic cells (D) are important in antigen presentation and activation of T cells, but they are not the primary immune cells involved in granuloma formation.