NucleobaseMurchison meteorite sample 1Murchison meteorite sample 2Murchison soil sampleIsoguanine0.50.04not detectedPurine0.20.02not detectedXanthine3...
GMAT Information and Ideas : (Ideas) Questions
| Nucleobase | Murchison meteorite sample 1 | Murchison meteorite sample 2 | Murchison soil sample |
|---|---|---|---|
| Isoguanine | 0.5 | 0.04 | not detected |
| Purine | 0.2 | 0.02 | not detected |
| Xanthine | 39 | 3 | 1 |
| Adenine | 15 | 1 | 40 |
| Hypoxanthine | 24 | 1 | 2 |
Employing high-performance liquid chromatography—a process that uses pressurized water to separate material into its component molecules—astrochemist Yashiro Oba and colleagues analyzed two samples of the Murchison meteorite that landed in Australia as well as soil from the landing zone of the meteorite to determine the concentrations of various organic molecules. By comparing the relative concentrations of types of molecules known as nucleobases in the Murchison meteorite with those in the soil, the team concluded that there is evidence that the nucleobases in the Murchison meteorite formed in space and are not the result of contamination on Earth.
Which choice best describes data from the table that support the team's conclusion?
Isoguanine and purine were detected in both meteorite samples but not in the soil sample.
Adenine and xanthine were detected in both of the meteorite samples and in the soil sample.
Hypoxanthine and purine were detected in both the Murchison meteorite sample 2 and in the soil sample.
Isoguanine and hypoxanthine were detected in the Murchison meteorite sample 1 but not in sample 2.
Step 1: Decode and Map the Passage
Part A: Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "Employing high-performance liquid chromatography—a process that uses pressurized water to separate material into its component molecules—astrochemist Yashiro Oba and colleagues analyzed two samples of the Murchison meteorite that landed in Australia as well as soil from the landing zone of the meteorite to determine the concentrations of various organic molecules." |
|
| "By comparing the relative concentrations of types of molecules known as nucleobases in the Murchison meteorite with those in the soil, the team concluded that there is evidence that the nucleobases in the Murchison meteorite formed in space and are not the result of contamination on Earth." |
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| [Data Table] |
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Part B: Provide Passage Architecture & Core Elements
Main Point: Scientists concluded that nucleobases in the Murchison meteorite formed in space rather than from Earth contamination based on comparing concentrations between meteorite samples and soil.
Argument Flow: The researchers used liquid chromatography to measure organic molecules in both meteorite samples and soil from where it landed. By comparing these concentrations, they determined that the nucleobases originated in space rather than being contaminated by Earth materials.
Step 2: Interpret the Question Precisely
What's being asked? Which data from the table supports the team's conclusion that nucleobases formed in space and are not from Earth contamination.
What type of answer do we need? Specific data evidence that backs up the conclusion about space origin versus Earth contamination.
Any limiting keywords? Must use data from the table and must specifically support their claim about space formation.
Step 3: Prethink the Answer
- If nucleobases formed in space (not from Earth contamination), we would expect to see nucleobases present in the meteorite samples but absent (or at much lower levels) in the soil sample
- The soil represents potential Earth contamination since it is from the landing zone
- The right answer should identify nucleobases that appear in both meteorite samples but are absent from the soil sample
Isoguanine and purine were detected in both meteorite samples but not in the soil sample.
- Isoguanine shows 0.5 and 0.04 in meteorite samples but "not detected" in soil
- Purine shows 0.2 and 0.02 in meteorite samples but "not detected" in soil
- This perfectly supports the conclusion - these nucleobases are present in the meteorite but completely absent from Earth soil, indicating space origin
Adenine and xanthine were detected in both of the meteorite samples and in the soil sample.
- States adenine and xanthine were found in meteorite AND soil
- This does not support the space origin conclusion - presence in soil suggests possible Earth contamination
Hypoxanthine and purine were detected in both the Murchison meteorite sample 2 and in the soil sample.
- Focuses on detection in both meteorite sample 2 AND soil
- Again, presence in soil does not support the space origin conclusion
Isoguanine and hypoxanthine were detected in the Murchison meteorite sample 1 but not in sample 2.
- Compares differences between the two meteorite samples themselves
- Does not address the key comparison between meteorite and soil needed to support the contamination conclusion