Nokea
Acquired immunity is a result of previous exposure
- A. serious illness
- B. to vaccination
- C. repeated exposure to the same factor
- D. treatment with penicillin
Correct Answer: B
Rationale: The correct answer is B: to vaccination. Acquired immunity is the immune response developed after exposure to a vaccine, which stimulates the immune system to recognize and remember specific pathogens. Vaccination helps the body build immunity without causing serious illness like choice A, without requiring repeated exposure like choice C, and without being related to treatment with penicillin like choice D. Vaccination mimics natural infection, prompting the body to produce memory cells that can respond more effectively when encountering the actual pathogen in the future.
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What is a primary reason that the normal immune response fails to contain the HIV infection?
- A. CD4+ T cells become infected with HIV and are destroyed.
- B. The virus inactivates B cells, preventing the production of HIV antibodies.
- C. Natural killer cells are destroyed by the virus before the immune system can be activated.
- D. Monocytes ingest infected cells, differentiate into macrophages, and shed viruses in body tissues.
Correct Answer: A
Rationale: HIV specifically targets CD4+ T cells, depleting the immune system's ability to mount an effective response against pathogens.
During the course of an immune response to a given antigen, affinity maturation results in survival of:
- A. B cells whose secretion of antibody occurs at a higher rate
- B. B cells whose antibodies bind the antigen more strongly
- C. T cells whose TCRs bind the antigen more strongly
- D. Both B and C are correct
Correct Answer: B
Rationale: Rationale:
1. Affinity maturation is the process where B cells produce antibodies with increased affinity for the antigen over time.
2. B cells whose antibodies bind the antigen more strongly have higher affinity.
3. Survival of B cells with higher affinity antibodies is crucial for effective immune response.
4. A is incorrect as rate of antibody secretion doesn't necessarily correlate with affinity.
5. C is incorrect as T cells are not directly involved in affinity maturation of antibodies.
6. D is incorrect since T cells are not affected by affinity maturation in the context of this question.
A protein-protein interaction domain present both in TLR-4 and MyD88 is:
- A. CARD
- B. TIR
- C. Leucine rich repeat (LRR)
- D. Immunoglobulin-like domain
Correct Answer: B
Rationale: The correct answer is B: TIR. This is because both TLR-4 and MyD88 contain a Toll/interleukin-1 receptor (TIR) domain, which mediates protein-protein interactions in the Toll-like receptor signaling pathway. The other options, such as A (CARD), C (LRR), and D (Immunoglobulin-like domain), are not present in both TLR-4 and MyD88 and do not play a significant role in their interaction in the signaling pathway. This makes B the most appropriate choice as it accurately identifies the common protein-protein interaction domain between TLR-4 and MyD88.
Which condition is associated with increased susceptibility to bacterial infections due to complement deficiencies?
- A. Asthma
- B. Systemic lupus erythematosus (SLE)
- C. Streptococcus pneumoniae infections
- D. Chronic hepatitis
Correct Answer: C
Rationale: The correct answer is C: Streptococcus pneumoniae infections. Complement deficiencies impair the body's ability to fight bacterial infections, particularly encapsulated bacteria like Streptococcus pneumoniae. Asthma (A), SLE (B), and chronic hepatitis (D) are not directly associated with increased susceptibility to bacterial infections due to complement deficiencies. Asthma is a chronic respiratory condition, SLE is an autoimmune disease, and chronic hepatitis affects the liver. Therefore, only Streptococcus pneumoniae infections are directly linked to complement deficiencies.
Monoclonal antibodies can be used to:
- A. Block the proliferation of cancer cells
- B. Target cancer cells for destruction
- C. Inhibit inflammatory immune responses
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D because monoclonal antibodies have the ability to block the proliferation of cancer cells by targeting specific antigens on the cancer cells. They can also target cancer cells for destruction through various mechanisms such as antibody-dependent cell-mediated cytotoxicity. Additionally, monoclonal antibodies can inhibit inflammatory immune responses by neutralizing pro-inflammatory mediators or blocking immune cell activation pathways. Therefore, all the options A, B, and C are correct, making D the correct answer.