Poison frogs become poisonous by isolating chemicals from their food and storing them in their skin. One such compound, epibatidine, is a stronger painkiller than morphine, but has not been tested in humans because even low doses are deadly to rodents. But for the frogs themselves, this powerful neurotoxin is totally impotent. According to a study published in Science, several groups of epibatidine-bearing frogs have independently evolved amino acid changes in the toxin's target, the nicotinic acetylcholine receptor. These modifications allow the amphibians to escape self-toxicity.
The main idea of the passage is that some types of poison frogs:
- A. have developed the capacity to protect themselves from the poison they carry in their skin
- B. could eventually produce a natural pain relief option for people who suffer from headaches
- C. combine chemicals from their food to create a toxic substance that keeps them safe from predators
- D. can be grouped based on the changes they've made to their nicotinic acetylcholine receptors
Correct Answer & Rationale
Correct Answer: A
Option A highlights the unique adaptation of certain poison frogs, emphasizing their ability to protect themselves from their own toxins. This reflects a key aspect of their survival strategy. Option B, while interesting, suggests a potential human application of frog toxins that is not the main focus of the passage. Option C inaccurately attributes the creation of toxins solely to food sources, overlooking the frogs' inherent toxic traits. Option D focuses on a specific biological mechanism that, while relevant, does not encapsulate the broader theme of self-protection central to the passage.
Option A highlights the unique adaptation of certain poison frogs, emphasizing their ability to protect themselves from their own toxins. This reflects a key aspect of their survival strategy. Option B, while interesting, suggests a potential human application of frog toxins that is not the main focus of the passage. Option C inaccurately attributes the creation of toxins solely to food sources, overlooking the frogs' inherent toxic traits. Option D focuses on a specific biological mechanism that, while relevant, does not encapsulate the broader theme of self-protection central to the passage.
Other Related Questions
The writer is considering adding the following sentence to the end of the fourth paragraph: 'Surprisingly, according to The Economist, there were 1.6 million commercial farms in Brazil in 2010.' Should the writer make this addition here?
- A. Yes, because it emphasizes the paragraph's focus on the economic power of large farms.
- B. Yes, because it uses concrete data to provide context about local farms and commercial farms.
- C. No, because it is unrelated to the economic challenges small farms may face.
- D. No, because it fails to show a clear connection to the paragraph's focus on supporting local farms.
Correct Answer & Rationale
Correct Answer: B
Adding the sentence enhances the paragraph by providing concrete data, which helps contextualize the discussion about local and commercial farms. It bridges the gap between the economic landscape and the realities faced by different types of farms, enriching the reader's understanding. Option A misinterprets the focus; while large farms are mentioned, the emphasis is on the economic challenges faced by smaller farms. Option C incorrectly suggests that the data is unrelated; understanding the number of commercial farms is essential to discussing the economic landscape. Option D overlooks that the data can indeed support a broader discussion about local farms by contrasting them with commercial operations.
Adding the sentence enhances the paragraph by providing concrete data, which helps contextualize the discussion about local and commercial farms. It bridges the gap between the economic landscape and the realities faced by different types of farms, enriching the reader's understanding. Option A misinterprets the focus; while large farms are mentioned, the emphasis is on the economic challenges faced by smaller farms. Option C incorrectly suggests that the data is unrelated; understanding the number of commercial farms is essential to discussing the economic landscape. Option D overlooks that the data can indeed support a broader discussion about local farms by contrasting them with commercial operations.
In context, the metaphor in the third sentence ('it was... years') chiefly serves to:
- A. Call attention to the age of the United States as a nation
- B. Question the literary value of the writings by Lewis and Clark
- C. Trivialize the accomplishments of the Lewis and Clark expedition
- D. Place the Lewis and Clark expedition into a broad context
Correct Answer & Rationale
Correct Answer: D
The metaphor in the third sentence effectively places the Lewis and Clark expedition within a broader historical and cultural context, emphasizing its significance in relation to the age of the nation and its development. Option A, while related to the age of the United States, does not capture the metaphor's broader implications. Option B misinterprets the metaphor, as it does not question literary value but rather highlights historical importance. Option C inaccurately suggests that the metaphor diminishes the expedition’s achievements, whereas it actually elevates their significance by situating them within a larger narrative.
The metaphor in the third sentence effectively places the Lewis and Clark expedition within a broader historical and cultural context, emphasizing its significance in relation to the age of the nation and its development. Option A, while related to the age of the United States, does not capture the metaphor's broader implications. Option B misinterprets the metaphor, as it does not question literary value but rather highlights historical importance. Option C inaccurately suggests that the metaphor diminishes the expedition’s achievements, whereas it actually elevates their significance by situating them within a larger narrative.
The passage indicates that ancient astronomers were 'baffled' because:
- A. Their observations disproved the poetic tales of early cosmologies
- B. They lacked the mathematical sophistication needed to calculate astronomical distances
- C. Their theories of planetary movements were more complicated than the movements themselves
- D. They could not reliably predict observable celestial phenomena
Correct Answer & Rationale
Correct Answer: D
Ancient astronomers were 'baffled' primarily because they struggled to reliably predict observable celestial phenomena. This unpredictability challenged their understanding and led to confusion in their astronomical models. Option A is incorrect as it implies a conflict with poetic tales, which was not the primary concern of astronomers. Option B misrepresents the issue; while mathematical sophistication was limited, the core problem was not solely about calculations. Option C inaccurately suggests that their theories were overly complex; rather, the issue lay in their inability to accurately forecast celestial events, which is the essence of their bafflement.
Ancient astronomers were 'baffled' primarily because they struggled to reliably predict observable celestial phenomena. This unpredictability challenged their understanding and led to confusion in their astronomical models. Option A is incorrect as it implies a conflict with poetic tales, which was not the primary concern of astronomers. Option B misrepresents the issue; while mathematical sophistication was limited, the core problem was not solely about calculations. Option C inaccurately suggests that their theories were overly complex; rather, the issue lay in their inability to accurately forecast celestial events, which is the essence of their bafflement.
Which choice best replaces the underlined portion in sentence 6 (reproduced below) to suggest that, for a time, people were completely caught up with news of the Leonid meteor shower? In the center of the quilt, the 'falling of the stars' illustrates the hours-long Leonid meteor shower that interested people on November 13, 1833.
- A. affected
- B. enthralled
- C. involved
- D. worried
Correct Answer & Rationale
Correct Answer: B
The term "enthralled" effectively conveys a sense of deep fascination and engagement, suggesting that people were completely captivated by the Leonid meteor shower. Option A, "affected," lacks the intensity and emotional connection implied in the context; it merely indicates a change rather than a strong interest. Option C, "involved," suggests participation but does not capture the sense of wonder that the meteor shower inspired. Option D, "worried," introduces an inappropriate negative connotation, as the context is one of excitement and awe, not concern.
The term "enthralled" effectively conveys a sense of deep fascination and engagement, suggesting that people were completely captivated by the Leonid meteor shower. Option A, "affected," lacks the intensity and emotional connection implied in the context; it merely indicates a change rather than a strong interest. Option C, "involved," suggests participation but does not capture the sense of wonder that the meteor shower inspired. Option D, "worried," introduces an inappropriate negative connotation, as the context is one of excitement and awe, not concern.