Nokea
Ribosomes associated with cells or organelles have a certain size, which is expressed in Svedberg units. Which associations are incorrect?
- A. cyanobacteria - 80s
- B. chloroplasts - 60s
- C. photosynthetic bacteria - 80s
- D. green algal cytoplasm - 80s
Correct Answer: A
Rationale: The correct answer is A because cyanobacteria have ribosomes measured in 70s, not 80s. Ribosomes in prokaryotes are either 70s (composed of 50s and 30s subunits) or 80s in eukaryotes (60s and 40s subunits). Choices B, C, and D are incorrect because chloroplasts, photosynthetic bacteria, and green algal cytoplasm all have ribosomes measured in 70s or 80s, consistent with their cell types.
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Which scientist is credited with identifying Toll-like receptors (TLRs) in innate immunity?
- A. Paul Ehrlich
- B. Jules Hoffman
- C. Edward Jenner
- D. Louis Pasteur
Correct Answer: B
Rationale: The correct answer is B: Jules Hoffman. He is credited with identifying Toll-like receptors (TLRs) in innate immunity. Hoffman's research provided crucial insights into how the immune system recognizes pathogens and triggers immune responses. Paul Ehrlich is known for his work on antibodies, Edward Jenner for developing the smallpox vaccine, and Louis Pasteur for his contributions to germ theory and vaccination. However, none of them are specifically associated with the discovery of Toll-like receptors in innate immunity.
An essential cofactor for restriction endonuclease enzyme activity is
- A. Zn2+
- B. Mg2+
- C. Co2+
- D. Ca2+
Correct Answer: B
Rationale: The correct answer is B: Mg2+. Mg2+ is an essential cofactor for restriction endonuclease enzymes because it stabilizes the enzyme-substrate complex, promotes proper binding of the enzyme to DNA, and facilitates the catalytic activity of the enzyme. Mg2+ ions help in the coordination of the active site residues and the phosphate backbone of DNA, which is crucial for the cleavage of DNA strands. Zn2+, Co2+, and Ca2+ do not provide the necessary coordination and stabilization required for restriction endonuclease enzyme activity, making them incorrect choices.
A nurse has educated a client on an epinephrine autoinjector. What statement by the client indicates additional instruction is needed?
- A. I don't need to go to the hospital after using it.
- B. I must carry two autoinjectors with me at all times.
- C. I will write the expiration date on my calendar.
- D. This can be injected right through my clothes.
Correct Answer: A
Rationale: The correct answer is A. If the client states they don't need to go to the hospital after using the epinephrine autoinjector, additional instruction is needed. The rationale is that after using an epinephrine autoinjector, it is crucial to seek medical attention immediately due to the potential for severe allergic reactions. Choice B is incorrect because carrying two autoinjectors is recommended in case the first dose is not effective. Choice C is incorrect as it demonstrates good practice in tracking the expiration date. Choice D is incorrect as it is acceptable to inject through clothes in an emergency situation.
Which scientist proposed the concept of clonal selection?
- A. Paul Ehrlich
- B. Macfarlane Burnet
- C. Louis Pasteur
- D. Elie Metchnikoff
Correct Answer: B
Rationale: The correct answer is B: Macfarlane Burnet. Burnet proposed the concept of clonal selection in the 1950s to explain how the immune system recognizes and responds to specific antigens. He suggested that lymphocytes with receptors specific to antigens undergo clonal expansion upon encountering the antigen. This hypothesis laid the groundwork for our understanding of adaptive immunity.
A: Paul Ehrlich developed the side-chain theory of antibody formation, not clonal selection.
C: Louis Pasteur is known for his work in microbiology and vaccination, not clonal selection.
D: Elie Metchnikoff is credited with discovering phagocytosis, not clonal selection.
What could happen to the woman’s serum osmolality as a result of this meal?
- A. Increased
- B. No change
- C. Decreased
- D. Unchanged
Correct Answer: B
Rationale: The meal contains high amounts of sodium from salt pork and gravy, which would increase serum osmolality due to increased sodium concentration in the blood.