Nokea
What is the lag phase of the primary antibody response?
- A. 1-3 days
- B. 5-10 days
- C. 10-15 days
- D. No lag phase
Correct Answer: B
Rationale: The lag phase of the primary antibody response refers to the time it takes for the immune system to generate specific antibodies after initial exposure to an antigen. The correct answer is B (5-10 days) because during this period, B cells are activated, undergo proliferation, differentiate into plasma cells, and start producing antibodies. This process takes time as the immune system needs to recognize the antigen, mount a response, and produce sufficient antibodies. Option A (1-3 days) is too short for the full activation and differentiation of B cells. Option C (10-15 days) is too long for the typical lag phase duration. Option D (No lag phase) is incorrect because there is always a lag phase before the peak antibody production in the primary immune response.
You may also like to solve these questions
What outcome would you least expect if the amount of template in a PCR fell significantly below the optimal amount?
- A. non-specific amplification
- B. increased yield
- C. Allelic drop-out (some alleles fail to amplify)
- D. Longer targets amplify poorly or fail
Correct Answer: B
Rationale: The correct answer is B: increased yield. If the amount of template in a PCR falls significantly below the optimal amount, it would be expected to result in a decreased yield rather than an increased yield. The template is essential for DNA amplification in PCR, and a lower amount would lead to fewer copies being produced. Non-specific amplification (choice A) can occur if there is too much template or incorrect primer annealing. Allelic drop-out (choice C) is likely to happen if there is insufficient template present to amplify all alleles. Longer targets amplifying poorly or failing (choice D) is also a common outcome when template concentration is low. Therefore, the least expected outcome would be an increased yield as that goes against the principle of PCR amplification.
Why is Edward Jenner's experiment on a young boy considered a scientific landmark?
- A. Jenner inoculated the young boy using material obtained from the scabs of a milkmaid who had suffered of a very mild form of smallpox. The boy never contracted the disease.
- B. Jenner inoculated the young boy first using material obtained from the scabs of a milkmaid who had suffered of a very mild form of smallpox; subsequently he inoculated the boy with virulent smallpox.
- C. Variolation was the crude practice of injecting smallpox in a way that would supposedly protect the recipient from getting a fatal form of the disease; Jenner instead injected the young boy with cowpox. The fact that the boy did not die proved that cowpox inoculation protects against smallpox
- D. Jenner noticed the milkmaids were protected from smallpox but were often affected by a mild disease caused by cowpox. He decided to inoculate a young boy with cowpox first and subsequently with smallpox to prove that exposing people to cowpox can make them immune from getting smallpox
Correct Answer: D
Rationale: Step 1: Jenner observed milkmaids were protected from smallpox due to prior exposure to cowpox.
Step 2: Jenner decided to inoculate a young boy with cowpox first.
Step 3: Jenner then inoculated the boy with smallpox to test immunity.
Step 4: The boy did not contract smallpox, demonstrating immunity.
Step 5: Conclusion: Jenner proved cowpox exposure can make individuals immune to smallpox.
Other choices are incorrect:
A: The boy never contracted smallpox, not just because of the mild form of smallpox in the milkmaid.
B: Inoculating with virulent smallpox first would not demonstrate cowpox immunity.
C: Jenner did not just substitute cowpox for smallpox; he specifically tested immunity by exposing the boy to both viruses.
Which mutated tumor suppressor gene is most likely to contribute to many types of cancer, including bladder, breast, colorectal, and lung?
- A. p53
- B. APC
- C. BRCA1
- D. BRCA2
Correct Answer: A
Rationale: The p53 gene is a critical tumor suppressor gene involved in preventing cancer by regulating the cell cycle and initiating apoptosis. Mutations in this gene are associated with many types of cancer.
Which of the following is NOT true with respect to T cell development?
- A. It establishes MHC restriction of the T cell repertoire
- B. It takes place in the thymus
- C. Thymic dendritic cells are involved
- D. It only occurs after the naïve T cell has been activated by antigen
Correct Answer: D
Rationale: The correct answer is D because T cell development starts in the thymus while the naïve T cell activation by antigen occurs outside of the thymus. T cell development involves positive and negative selection, establishing MHC restriction, and interaction with thymic dendritic cells for maturation. Naïve T cells are activated by antigens in the periphery, not during T cell development in the thymus. Therefore, D is the correct answer as it does not align with the process of T cell development.
Which of the following is correct about lectin receptors?
- A. They recognize microbial carbohydrates
- B. They are expressed on phagocytes
- C. They can be classified as pattern recognition receptors
- D. All of the above is correct
Correct Answer: D
Rationale: The correct answer is D - All of the above. Lectin receptors recognize microbial carbohydrates, are expressed on phagocytes, and can be classified as pattern recognition receptors. Lectins are proteins that bind specifically to certain carbohydrates, allowing them to recognize and interact with pathogens. Phagocytes express lectin receptors to help identify and engulf pathogens. Additionally, lectin receptors are considered pattern recognition receptors because they recognize specific patterns or structures commonly found on pathogens. Therefore, all three statements are true, making option D the correct answer.