Most Schoolchildren in North America are Familiar with the "Red on Black, Red on GMAT Reading Comprehension

Reading Passage Question

Most schoolchildren in North America are familiar with the "red on black, red on yellow" rhyme, a mnemonic used to distinguish the venomous and deadly coral snake from the relatively harmless but similarly colored milk snake. In full, the most common variant holds that "red on black, pat on the back; red on yellow, kill a fellow.” When two species evolve to resemble one another so closely to require such memory aids, it is almost impossibly unlikely that the resemblance is due to chance. Instead, one of the two similar species likely evolved to resemble the other, with the second species gaining a reproductive advantage by being mistaken for the first. If the original species is particularly harmful, as in the case of the monarch butterfly, whose wings are covered with particles that are poisonous to birds and mammals, a species that evolves to resemble it may be subject to reduced predation. Those animals that in turn evolve ways to recognize and avoid the monarch butterfly are likely to avoid the lookalike as well, even if the lookalike “sheep-in-wolves’ clothing” does not possess the poisonous defense. The success of the monarch butterflies mimic, the viceroy butterfly, is predicated upon precisely this strategy, which biologists call Batesian mimicry.

The evolutionary relationship between the milk snake and the coral snake is more complex, as the two species did not evolve in a common environment or in an overlapping one, and until relatively recently in their evolutionary history—well after the two species converged upon the four-color color scheme—the two shared no significant predatory threats. Rather, each snake evolved independently to resemble a third species that, at certain points over the past hundred thousand years, lived in territories that overlapped the range of both. This species, the so-called “false” coral snake, was the first to evolve the distinctive coloration.

“False” coral snakes, unlike the milk snake, are venomous but much less so than the coral snake, which can easily “kill a fellow,” as the rhymes warn, due to its venom’s potent neurotoxic properties that can cause respiratory failure in animals as large as horses after only a single bite. The “false” coral snake, on the other hand, possesses a venomous bite that is sufficient to dissuade birds of prey such as falcons and herons from attacking but is not dangerous to mammals larger than the common housecat. While the advantage to the milk snake from mimicking the “false” coral snake is similar to that which the viceroy gains from the monarch, the more venomous coral snake benefits in a different way. As Wolfgang Wickler first detailed, the coral snake’s venom is so powerful that it could not benefit from predators learning to recognize it and avoid it, as any predator bitten would have died and been unable to pass on such behavior to its offspring. By coming to resemble a less venomous snake, the coral snake in a sense found a loophole, allowing the “false” coral snake to serve as a sort of advertisement for its already evolved deadly poison. Potential predators that have developed instincts to avoid the “false” coral snake will also avoid the “true” coral snake, blissfully unaware that the latter is actually the more dangerous of the two. Such behavior Wickler named Mertensian mimicry.

“Most schoolchildren in North America are familiar with the "red on black, red on” is a GMAT Reading Comprehension passage with a series of answers. To qualify for the GMAT RC test, the candidates must possess a solid understanding of the English GMAT reading comprehension. The comprehension contains ten questions in this GMAT Reading Comprehension portion. GMAT Reading Comprehension questions intend to measure the candidate’s skill to comprehend and employ ideas or concepts. The candidates can update their knowledge by practising the GMAT Reading Comprehension Practice Questions.

Solutions and Explanation

1. According to the passage, which of the following is true of “false” coral snakes?

1. They are less poisonous than coral snakes but not less poisonous than milk snakes.
2. They evolved in an environment that overlapped with neither the coral snake nor the milk snake.
3. They possess a venomous bite that can harm even large mammals.
4. Their evolutionary relationship to the milk and coral snake will likely never be fully understood.
5. Birds of prey such as herons and falcons form an occasional part of their diets.

2. Which of the following best describes the author’s primary aim in writing this passage?

1. To compare two different approaches to interpreting the evolutionary relationship of closely related species
2. To summarize the findings of several studies regarding the evolutionary relationship of three snake species
3. To argue for a particular hypothesis regarding the reason for the shared coloration of the milk, coral, and “false” coral snake
4. To relate and discuss two related evolutionary strategies through the extended discussion of a specific example
5. To cite examples of species whose evolutionary strategies do not fit well into scientists’ established categories.

3. According to the passage, which of the following is a reason that the relationship between milk snakes and coral snakes is unlikely to be considered an example of Batesian mimicry?

1. The potent neurotoxic properties of the coral snake’s venom far outclasses the natural defenses of the less dangerous milk snake.
2. The two snakes lived in territories that overlapped with the “false” coral snake.
3. The coral snake capitalizes on already developed instincts in predator species to avoid the milk snake.
4. It was only after the two species had independently acquired the similar coloration that their territories overlapped in any significant way.
5. The surface of the coral snake's skin is covered with poisonous particles that blind birds and mammals, while the milk snake’s is not.

4. According to the passage, an important difference between Mertensian and Batesian mimicry is that

1. in Batesian mimicry, the mimicking species lives in environments that do not overlap the mimicked species’ domain.
2. in Mertensian mimicry, the species mimicked is less harmful than the mimicking species.
3. Mertensian mimics are more successful when the two species vary greatly in their ability to harm potential predators.
4. Batesian mimics are more likely to be found in the insect kingdom, while Mertensian mimics are found among more complicated species.
5. in Mertensian mimicry, three or more species come to resemble one another, while Batesian mimics are found only as pairs.

5. With which of the following would the author of the passage MOST likely agree?

1. When an animal possesses venom so potent that it would kill most potential predators, that venom is likely to be an evolutionary disadvantage.
2. Mnemonic rhymes such as those used to distinguish the two snakes should not be considered foolproof.
3. A close resemblance between two species found in the same environment should rarely, if ever, be attributed to happenstance.
4. When a species lacks natural predators, it is unlikely that the species will be found to be poisonous.
5. Species that inhabit partially or completely overlapping environments tend to evolve to resemble one another.

6. The author mentions the viceroy butterfly most likely in order to

1. contrast the characteristics of Batesian mimicry with those of Mertensian mimicry.
2. call into question a theory proposed earlier in the passage by providing a counterexample.
3. propose an alternate interpretation to a commonly held belief about the relationship between two species.
4. present an example of a species that shares an evolutionary strategy with species discussed later in the passage.
5. further illustrate the importance of mimicry in guaranteeing the survival of a species’ offspring.

7. According to the passage, each of the following is true of the “false” coral snake EXCEPT

1. the pattern of its multicolored stripes helps the coral snake ward off potential predators.
2. its venom is sufficiently poisonous to damage animals as large as a bird of prey.
3. it gains an evolutionary advantage by being mistaken for the more venomous coral snake.
4. its habitat has changed over the course of its evolutionary history.
5. its coloration is easily mistaken for that of the milk snake.

8. According to the passage, which of the following situations would most properly be described as an instance of Mertensian mimicry?

1. A nonpoisonous desert rattlesnake that is prey to many species slowly changes in appearance over many generations in order to be less recognizable to some of its predators
2. A species of cuckoo bird that lays eggs resembling those of a related bird species in order to trick the other bird into raising its offspring
3. A deadly species of puffer fish that evolved a scale pattern that matches the geometric patterns typical of the coral species in which it lives
4. An orchid whose petals evolved to resemble the female of a species of bees in order to attract pollinators
5. An octopus that lacks Natural weaponry changes the color and shape of its body to resemble a poisonous lionfish or a sea snake

9. The passage contains information to answer which of the following questions?

1. Is Mertensian mimicry more common in nature than Batesian mimicry?
2. How Iong does it take for one species to evolve so that it comes to resemble another?
3. Is it possible for the physical characteristics of a species to change in response to the activity of other species with which it is neither predator nor prey?
4. If a species successfully mimics a similar but poisonous species, can it come to replace that species in an ecosystem?
5. What experimental methodology first allowed scientists to unravel the secrets of Mertensian mimicry?

10. According to the description given in the passage, which of the following would biologists likely take as a reason AGAINST classifying the relationship between the “false” coral snake and the coral snake as an instance of Mertensian mimicry?

1. A fourth, similarly colored, non-venomous snake species that resembles the two coral snakes.
2. Evidence that the coral snake possessed the distinctive four-color scheme before the “false” coral snake
3. The discovery of a predator that has developed a resistance to the neurotoxin possessed by the coral snake
4. Signs that the habitat of the coral snake and the “false” coral snake no longer overlap substantially
5. New evidence that the venom of the coral snake kills primarily by causing renal, rather than respiratory, failure

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