Nokea
Select the property that applies only to pathogens:
- A. Replicate in (or on) a host
- B. Infect host cells
- C. Cause disease in a host with normal immune functions
- D. Are transmitted between individuals of a given species
Correct Answer: C
Rationale: The correct answer is C because pathogens are microorganisms that specifically cause disease in a host with normal immune functions. Pathogens have mechanisms to evade or overcome the host's immune system, leading to the development of diseases. Choices A and B are characteristics of both pathogens and non-pathogenic organisms. Choice D is incorrect because not all pathogens are transmitted between individuals of the same species; some pathogens can be transmitted from animals to humans or through environmental sources.
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The 'major histocompatibility complex' (MHC) proteins involved in antigen presentation to T cells were first noted during studies of:
- A. Innate immunity
- B. Allergy
- C. Transplantation
- D. Autoimmunity
Correct Answer: C
Rationale: The correct answer is C: Transplantation. MHC proteins play a crucial role in transplant rejection by presenting antigens to T cells, initiating an immune response against foreign tissues. This discovery was significant in understanding transplant immunology. Choices A, B, and D are incorrect because innate immunity involves nonspecific defense mechanisms, allergies are mediated by IgE antibodies, and autoimmunity involves the immune system attacking self-antigens, none of which directly relate to the discovery of MHC proteins in transplantation studies.
Why do opportunistic diseases develop in an individual with AIDS?
- A. They are side effects of drug treatment of AIDS.
- B. They are sexually transmitted to individuals during exposure to HIV.
- C. They are characteristic in individuals with stimulated B and T lymphocytes.
- D. These infections or tumors occur in a person with an incompetent immune system.
Correct Answer: D
Rationale: Opportunistic diseases arise because the immune system is severely compromised in individuals with AIDS, making them susceptible to infections and cancers they would otherwise resist.
To produce better flu vaccines, we want:
- A. To block spreading of the infection by inducing a cytotoxic T cell response that would directly prevent viral entry into uninfected cells
- B. To induce the formation of strain-specific neutralizing antibodies that would prevent viral entry into uninfected cells
- C. To induce antibodies able to recognize HA across different strains by targeting less variable regions of HA
- D. All of the above is reasonably expected to improve the success of flu vaccines
Correct Answer: D
Rationale: The correct answer is D because all the options contribute to improving flu vaccines. A cytotoxic T cell response can help block viral spread, strain-specific neutralizing antibodies can prevent viral entry, and targeting less variable regions of HA with antibodies can improve recognition across strains. Each approach addresses different aspects of the immune response to enhance vaccine efficacy. Therefore, combining these strategies can lead to a more comprehensive and effective flu vaccine. Options A, B, and C alone are not sufficient as they only target specific aspects of the immune response, while option D encompasses a holistic approach for better vaccine success.
The way in which some organism supplies some other organism with food and energy known as
- A. Food chains
- B. Food Network
- C. Pyramid of power
- D. levels of nutrition
Correct Answer: A
Rationale: The correct answer is A: Food chains. A food chain depicts the flow of energy and nutrients from one organism to another in an ecosystem. It shows how energy is transferred from producers to consumers. Food network (B) is a more complex and interconnected system than a simple linear chain. Pyramid of power (C) represents the energy flow in an ecosystem, not the transfer of food. Levels of nutrition (D) is not a term commonly used to describe how organisms transfer food and energy.
According to the hygiene hypothesis, which of the following factors protect us from developing immune diseases?
- A. Small family size
- B. Good sanitation
- C. Low antibiotic use
- D. Living in "westernized" countries
Correct Answer: C
Rationale: The correct answer is C: Low antibiotic use. The hygiene hypothesis suggests that reduced exposure to infections, which can happen with low antibiotic use, can lead to an increased risk of immune diseases. Antibiotics can disrupt the balance of gut microbiota, which plays a crucial role in immune system development. A: Small family size may not necessarily protect against immune diseases as it does not directly relate to exposure to infections. B: Good sanitation can reduce the spread of infections but may not necessarily protect against immune diseases. D: Living in "westernized" countries is a broad factor and does not directly address the impact of low antibiotic use on immune diseases.