Nokea
What is the primary role of phagocytosis in innate immunity?
- A. Killing cancer cells
- B. Engulfing and digesting pathogens
- C. Producing antibodies
- D. Activating complement proteins
Correct Answer: B
Rationale: The primary role of phagocytosis in innate immunity is to engulf and digest pathogens. Phagocytes such as macrophages and neutrophils recognize and engulf bacteria, viruses, and other harmful substances to prevent infections. They digest these pathogens using enzymes and destroy them. This process is crucial in the initial defense against infections. Option A is incorrect because phagocytosis primarily targets pathogens, not cancer cells. Option C is incorrect because producing antibodies is a function of adaptive immunity, not innate immunity. Option D is incorrect because activating complement proteins is a separate mechanism in the immune response.
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The Calvin cycle:
- A. is a C5 pathway
- B. is used by all photoautotrophic microorganisms
- C. is a C4 pathway
- D. is a dark reaction
Correct Answer: D
Rationale: The Calvin cycle is a series of biochemical reactions that take place in the stroma of chloroplasts during photosynthesis. It occurs in the dark phase (without direct light requirement), making choice D correct. Choice A is incorrect because the Calvin cycle is a C3 pathway, not C5. Choice B is incorrect because not all photoautotrophic microorganisms use the Calvin cycle; some use alternative pathways. Choice C is incorrect because C4 pathway is a different photosynthetic pathway that occurs in certain plants to minimize photorespiration.
What describes a primary use of biologic therapy in cancer treatment?
- A. Protect normal,rapidly reproducing cells of the gastrointestinal system from damage during chemotherapy
- B. Prevent the fatigue associated with chemotherapy and high-dose radiation as seen with bone marrow depression
- C. Enhance or supplement the effects of the host’s immune responses to tumor cells that produce flu-like symptoms
- D. Depress the immune system and circulating lymphocytes as well as increase a sense of well-being by replacing central nervous system deficits
Correct Answer: C
Rationale: Biologic therapy enhances the immune response against tumor cells, often causing flu-like symptoms.
What do pattern recognition receptors (PRRs) identify?
- A. Specific antigens
- B. Pathogen-associated molecular patterns (PAMPs)
- C. Host self-proteins
- D. Specific viruses only
Correct Answer: B
Rationale: Pattern recognition receptors (PRRs) identify Pathogen-associated molecular patterns (PAMPs) because PAMPs are unique molecules found on pathogens that trigger an immune response. PRRs recognize these patterns to distinguish between self and non-self. This recognition is crucial for initiating an immune response against potential threats. Specific antigens (A) and specific viruses only (D) are too narrow in scope as PRRs are designed to detect a wide range of patterns. Host self-proteins (C) are recognized by other mechanisms in the immune system to prevent autoimmunity.
Which of these are a type of mutation?
- A. base substitution
- B. translocation
- C. insertion sequences
- D. recombination
Correct Answer: D
Rationale: The correct answer is D: recombination. Recombination is a type of mutation that involves the exchange of genetic material between two DNA molecules. This process can lead to genetic variation and evolution. Base substitution (A) is a point mutation where one base is replaced by another. Translocation (B) involves the movement of a segment of DNA to another location in the genome. Insertion sequences (C) are short segments of DNA that can move within the genome but are not considered a type of mutation. Recombination (D) is the only choice directly related to a type of mutation involving the exchange of genetic material.
Attenuated vaccines can be obtained by
- A. Passage through cultured cells
- B. Formaldehyde treatment
- C. The use of viral vectors carrying pathogen subunits
- D. All of the above treatments would lead to attenuated vaccines
Correct Answer: A
Rationale: The correct answer is A: Passage through cultured cells. Attenuated vaccines are produced by weakening the pathogen through serial passages in cultured cells, reducing virulence while maintaining immunogenicity. Formaldehyde treatment (B) disrupts the pathogen's structure and is used for inactivated vaccines. The use of viral vectors carrying pathogen subunits (C) is a method for creating subunit vaccines, not attenuated vaccines. Therefore, D is incorrect as not all treatments lead to attenuated vaccines.