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
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.
Tchaikovsky's Nutcracker leaves an impression on audiences: children especially remember the dazzling costumes and stirring music. Which word best completes the sentence?
- A. amorphous
- B. indelible
- C. ineffable
- D. inscrutable
Correct Answer & Rationale
Correct Answer: B
The word "indelible" effectively conveys the lasting impact that Tchaikovsky's Nutcracker has on audiences, particularly children, suggesting that the memories created are unforgettable. Option A, "amorphous," refers to something lacking a clear shape or form, which does not apply to the vivid impressions made by the performance. Option C, "ineffable," describes something too great to be expressed in words, which, while fitting in some contexts, does not specifically capture the idea of lasting memory. Option D, "inscrutable," means something that is difficult to understand or interpret, which is not relevant to the memorable experience described.
The word "indelible" effectively conveys the lasting impact that Tchaikovsky's Nutcracker has on audiences, particularly children, suggesting that the memories created are unforgettable. Option A, "amorphous," refers to something lacking a clear shape or form, which does not apply to the vivid impressions made by the performance. Option C, "ineffable," describes something too great to be expressed in words, which, while fitting in some contexts, does not specifically capture the idea of lasting memory. Option D, "inscrutable," means something that is difficult to understand or interpret, which is not relevant to the memorable experience described.
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.
To make the third and fourth paragraphs most logical, sentence 12 should be placed:
- A. where it is now
- B. after sentence 8
- C. after sentence 9
- D. after sentence 13
Correct Answer & Rationale
Correct Answer: D
Placing sentence 12 after sentence 13 enhances the flow by effectively connecting the ideas presented in the preceding sentences. This positioning allows for a smooth transition, maintaining coherence in the narrative. Option A retains sentence 12 in its current position, disrupting the logical progression of the paragraphs. Option B, placing it after sentence 8, creates a gap in context, as the ideas would not align well. Option C, following sentence 9, also fails to provide the necessary linkage, leaving the reader confused about the relationship between the concepts. Thus, option D is the most logical choice for clarity and coherence.
Placing sentence 12 after sentence 13 enhances the flow by effectively connecting the ideas presented in the preceding sentences. This positioning allows for a smooth transition, maintaining coherence in the narrative. Option A retains sentence 12 in its current position, disrupting the logical progression of the paragraphs. Option B, placing it after sentence 8, creates a gap in context, as the ideas would not align well. Option C, following sentence 9, also fails to provide the necessary linkage, leaving the reader confused about the relationship between the concepts. Thus, option D is the most logical choice for clarity and coherence.