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.
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.
In context, which word or phrase is best to insert at the beginning of sentence 11? Sentence 11: He spent most of his time writing poems in Spanish instead of studying English.
- A. In addition.
- B. For example.
- C. However.
- D. Indeed.
Correct Answer & Rationale
Correct Answer: C
The choice of "However" effectively contrasts the subject's choice to write poems in Spanish with the expectation that he should be studying English. This juxtaposition highlights a shift in focus, emphasizing the divergence from expected behavior. Option A, "In addition," suggests continuity rather than contrast, which does not align with the sentence's intent. Option B, "For example," implies that the sentence will provide an instance, which is not the case here. Option D, "Indeed," reinforces a statement rather than introducing a contrasting idea, making it unsuitable for the context.
The choice of "However" effectively contrasts the subject's choice to write poems in Spanish with the expectation that he should be studying English. This juxtaposition highlights a shift in focus, emphasizing the divergence from expected behavior. Option A, "In addition," suggests continuity rather than contrast, which does not align with the sentence's intent. Option B, "For example," implies that the sentence will provide an instance, which is not the case here. Option D, "Indeed," reinforces a statement rather than introducing a contrasting idea, making it unsuitable for the context.
Which best replaces the word 'appropriate' in sentence 3 (reproduced below)? When chefs and other consumers appropriate local products rather than goods that have been transported across long distances to chain stores, they can enjoy better prices while bettering the local economy.
- A. gain
- B. retrieve
- C. purchase
- D. redeem
Correct Answer & Rationale
Correct Answer: C
In the context of the sentence, "appropriate" conveys the idea of acquiring or buying local products. Option A, "gain," implies obtaining something but lacks the specificity of a transaction, making it less suitable. Option B, "retrieve," suggests taking back something previously owned, which does not fit the context of purchasing local goods. Option D, "redeem," typically refers to exchanging something for a benefit or value, often in a promotional context, which does not align with the intended meaning of acquiring local products. Thus, "purchase" accurately reflects the act of buying local goods.
In the context of the sentence, "appropriate" conveys the idea of acquiring or buying local products. Option A, "gain," implies obtaining something but lacks the specificity of a transaction, making it less suitable. Option B, "retrieve," suggests taking back something previously owned, which does not fit the context of purchasing local goods. Option D, "redeem," typically refers to exchanging something for a benefit or value, often in a promotional context, which does not align with the intended meaning of acquiring local products. Thus, "purchase" accurately reflects the act of buying local goods.