Researchers Traditionally have Attempted to Track Animals by Tagging Them.

Reading Passage Question

Researchers traditionally have attempted to track animals by tagging them. Seeking an alternative tracking method, Brian W. Bowen, an evolutionary geneticist, turned to four green turtle breeding sites in the Atlantic and the Caribbean. He and his co-workers reported that turtles from the four breeding sites tended to have slightly different genetic markings.

Bowen analyzed mitochondrial DNA from eggs and hatchlings. The existence of variations in DNA among geographically distinct groups has helped scientists evaluate the different theories of the mating habits of the green turtle. Their findings, Bowen asserts, lend credence to the “natal homing” theory. This theory holds that while reptiles born in different regions may share common feeding grounds away from home, the animals part company at breeding time, each swimming hundreds or thousands of miles to breed and nest at its own birthplace.

Bowen and his co-workers, however, offer several caveats to the interpretation of their findings. They note that turtles from two of the nesting sites—Florida’s Hutchinson Island and Costa Rica’s Tortuguero sanctuary—had indistinguishable mitochondrial DNA sequences. This finding indicates that either some social mixing occurred between these two groups or that the DNA test was not sensitive enough to detect extremely subtle differences in DNA. In addition, they report that one of eight study turtles from Aves Island, off Venezuela, showed the same genetic pattern as the Tortuguero and Hutchinson turtles in their sample. Nonetheless, Bowen’s study appears to have bolstered the idea that most populations of green turtles are genetically distinct, and that the turtles return to their birthplaces at nesting time.

“Researchers traditionally have attempted to track animals by tagging them.” - this is a GMAT reading comprehension passage with answers. Candidates need a strong knowledge of English GMAT reading comprehension.

This GMAT Reading Comprehension consists of 7 comprehension questions. The GMAT Reading Comprehension questions are designed for testing candidates’ abilities in understanding, analyzing, and applying information or concepts. Candidates can actively prepare with the help of GMAT Reading Comprehension Practice Questions.

Solution and Explanation

1. It can be inferred from the passage that the turtles from the Aves Island study

1. had, with the exception of one, genetic patterns distinct from those in the Tortuguero study
2. have shown that using DNA to track turtles is a flawed technique
3. all exhibited genetic patterns similar to those of the Hutchinson and Tortuguero study turtles
4. are part of an endangered species
5. had DNA that differs from those turtles that are from Venezuela

2. The primary purpose of this passage is to

1. disprove a previously existing theory
2. present a new idea along with some data
3. establish the infallibility of a new concept
4. confirm the validity of a novel hypothesis
5. track the development of a particular species

3. The information provided in the passage about Bowen's research can be used to answer which of the following questions?

1. Does social mixing occur between turtles from Florida's Hutchinson Island and Costa Rica's Tortuguero sanctuary?
2. Is there extensive interbreeding among green turtles from different areas?
3. To what extent can DNA testing be used to detect genetic differences?
4. Does tagging wild animals with metal disks or wires alter their mating habits?
5. By what mechanism do green turtles find their way back to their birthplace when they are ready to breed?

4. According to the passage, the discovery of the “existence of variations in DNA among geographically distinct" (Highlighted) turtle groups has

1. helped Bowen to become one of the field's leading experts
2. discredited previous notions of turtle breeding
3. confirmed the existence of a single original species of turtle
4. given some validity to the "natal homing" theory
5. explained similarities between turtles with subtle DNA differences

5. According to the passage, Bowen developed his natural markings tracking method in order to

1. find a way to track turtles without interfering in their natural routines
2. discover an alternative to tagging animals
3. overcome difficulties in tagging turtles with disks or wires
4. show that the possibilities of DNA technology are virtually limitless
5. lend credence to the "natal homing" theory

6. Which of the following would most strengthen the “natal homing" theory concerning the genetic differences among green turtles?

1. New studies indicate that green turtles can interbreed and their offspring still retain genetic distinctions.
2. The population of green turtles at Florida's Hutchinson Island and Costa Rica's Tortuguero sanctuary has declined in recent years.
3. Bowen was recently asked to do further research on genetic differences among green turtles.
4. Recent tests found that there were subtle differences between the mitochondrial UNA sequences found in turtles from Florida's Hutchinson Island and Costa Rica's Tortuguero sanctuary.
5. Research done on DNA testing has shown that DNA is not always a reliable measure of genetic differences.

7. According to the passage, which of the following supports the contention that green turtles rarely interbreed?

1. Some turtles from Florida's Hutchinson Island and Costa Rica's Tortuguero sanctuary had indistinguishable mitochondrial DNA sequences.
2. One of eight turtles studied from Aves Island, Venezuela shared a genetic pattern characteristic of turtles from a different breeding ground.
3. When analyzing the DNA of turtles, scientists found differences in the genetic makeup of turtles from various areas.
4. Bowen's team found a discrete mitochondrial pattern in each turtle they studied.
5. Turtles from each nesting ground share common feeding grounds that may be thousands of miles apart.

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