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.
Which choice best replaces the underlined portion of sentence 2 (reproduced below)? The pictorial quilts created by a former slave named Harriet Powers, in addition, were remarkable for their bold storytelling techniques and their unique subject matter.
- A. by contrast,
- B. for example,
- C. it so happens,
- D. moreover,
Correct Answer & Rationale
Correct Answer: D
The phrase "in addition" suggests that the following information will build on or add to the previous point. Option D, "moreover," effectively conveys this continuation of thought, emphasizing that Harriet Powers' quilts not only have a historical significance but also possess remarkable qualities. Option A, "by contrast," implies a comparison that highlights differences, which does not fit the context. Option B, "for example," indicates a specific illustration rather than adding information. Option C, "it so happens," is too vague and does not establish a clear connection to the preceding statement. Thus, "moreover" is the most suitable choice for enhancing the sentence's cohesiveness.
The phrase "in addition" suggests that the following information will build on or add to the previous point. Option D, "moreover," effectively conveys this continuation of thought, emphasizing that Harriet Powers' quilts not only have a historical significance but also possess remarkable qualities. Option A, "by contrast," implies a comparison that highlights differences, which does not fit the context. Option B, "for example," indicates a specific illustration rather than adding information. Option C, "it so happens," is too vague and does not establish a clear connection to the preceding statement. Thus, "moreover" is the most suitable choice for enhancing the sentence's cohesiveness.
In context, where would the following sentence best be placed? How long did it take sauropods to grow to full adult size?
- A. After sentence 3
- B. After sentence 8
- C. After sentence 9
- D. After sentence 12
Correct Answer & Rationale
Correct Answer: C
Placing the question "How long did it take sauropods to grow to full adult size?" after sentence 9 is most effective as it follows a discussion about sauropod growth patterns, providing a logical transition into the specifics of their growth duration. Option A, after sentence 3, is too early as it lacks the necessary context about sauropod growth. Option B, after sentence 8, is close but doesn't fully prepare the reader for the specific inquiry about growth duration. Option D, after sentence 12, is too late, as it disrupts the flow by introducing a new question after concluding details about sauropods.
Placing the question "How long did it take sauropods to grow to full adult size?" after sentence 9 is most effective as it follows a discussion about sauropod growth patterns, providing a logical transition into the specifics of their growth duration. Option A, after sentence 3, is too early as it lacks the necessary context about sauropod growth. Option B, after sentence 8, is close but doesn't fully prepare the reader for the specific inquiry about growth duration. Option D, after sentence 12, is too late, as it disrupts the flow by introducing a new question after concluding details about sauropods.
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.