Nokea
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.
You may also like to solve these questions
Identify the incorrect statement in regard to immunoglobulins (Ig)
- A. Are made up of two identical light chains and two identical heavy chains
- B. Cannot recognize conformational antigens on viral particles
- C. Can recognize only exposed epitopes of pathogens
- D. Expressed early during B cell development on the membrane of B cell precursors (pre- B cells)
Correct Answer: B
Rationale: The correct answer is B because immunoglobulins can indeed recognize conformational antigens on viral particles. Immunoglobulins have variable regions that can bind to a wide range of antigen shapes. Choice A is correct as Ig structure consists of two light and two heavy chains. Choice C is incorrect as immunoglobulins can also bind to internal epitopes. Choice D is incorrect as Ig expression starts during the late B cell development stage.
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.
What is included in the humoral immune response?
- A. Surveillance for malignant cell changes
- B. Production of antigen-specific immunoglobulins
- C. Direct attack of antigens by activated B lymphocytes
- D. Releasing cytokines responsible for destruction of antigens
Correct Answer: B
Rationale: The humoral immune response involves the production of antigen-specific antibodies (immunoglobulins) by B cells, which neutralize pathogens.
Which of the following represents a typical match between pathogen type and Th subset response?
- A. Virus : TH1
- B. Intracellular bacteria : TH2
- C. Virus : TH17
- D. Parasitic worm : TH1
Correct Answer: A
Rationale: The correct answer is A. Virus typically triggers a Th1 response because Th1 cells are specialized in combating intracellular pathogens like viruses. Th2 response is more common for extracellular parasites, making choice B incorrect. TH17 response is usually associated with fungal infections and autoimmune diseases, making choice C incorrect. Parasitic worms usually induce a Th2 response due to their extracellular nature, making choice D incorrect.
Which of the following lymphoid tissues has both hematopoietic and immune functions and acts as an emergency reservoir of blood and filters the blood as well?
- A. Tonsils and adenoids
- B. Thymus gland
- C. Spleen
- D. Lymph nodes
Correct Answer: C
Rationale: The spleen has both hematopoietic and immune functions acting as a blood filter and reservoir and plays a key role in removing old or damaged red blood cells.