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 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.
In context, which of the following is the best way to revise and combine sentences 1 and 2 (reproduced below)? Sauropods, known today as the largest dinosaurs, were long-necked giants. Their fossils have baffled scientists for decades.
- A. The fossils of sauropods, the long-necked giants who are known today as the largest dinosaurs, have baffled scientists for decades.
- B. Sauropods, long-necked giants, are known today as the largest dinosaurs whose fossils have baffled scientists for decades.
- C. Scientists have been baffled for decades by sauropod fossils; they are known today as the largest dinosaurs, being giants with long necks.
- D. Scientists studying fossils of the giant, long-necked dinosaurs called sauropods have been baffled by the largest dinosaurs known today for decades.
Correct Answer & Rationale
Correct Answer: A
Option A effectively combines the two sentences, maintaining clarity and coherence. It clearly identifies sauropods as long-necked giants and links them directly to their fossils, which have puzzled scientists, all in a single, fluid statement. Option B, while informative, awkwardly positions the phrase "whose fossils" and slightly disrupts the flow. Option C introduces unnecessary complexity with a semicolon and the phrase "being giants," which can confuse the reader. Option D is overly verbose and convoluted, making it less effective in conveying the main ideas succinctly.
Option A effectively combines the two sentences, maintaining clarity and coherence. It clearly identifies sauropods as long-necked giants and links them directly to their fossils, which have puzzled scientists, all in a single, fluid statement. Option B, while informative, awkwardly positions the phrase "whose fossils" and slightly disrupts the flow. Option C introduces unnecessary complexity with a semicolon and the phrase "being giants," which can confuse the reader. Option D is overly verbose and convoluted, making it less effective in conveying the main ideas succinctly.
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.