Self-paced
This passage was adapted from an article published in 2000.
P1
Problem ·
Computer chips will hit a point where they can't be made any smaller
With current methods, transistors (devices that make up computer chips) cannot be made smaller than 25 nanometers.
Potential solution ·
Natural chemical processes might produce smaller molecules that act like transistors
Belcher and Hu ·
B and H are investigating peptides
Others are researching DNA to try to create small transistor-like molecules. B and H are researching something else -- peptides.
P2
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Background leading to research ·
Arose from research that found peptides could cause calcium carbonate to form structure found in abalone shell
B and H thought peptides might create crystalline structures associated with transistors.
B and H's research ·
Grew a billion different peptides, found that some can bind to semiconductor materials
P3
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Future research ·
Identifying additional organic compounds that can bind to additional semiconductor mateirals
Passage Style
Problem-analysis
Single position
22.
Which one of the following, ██ █████ █████ ███ ████ ███████ ██ █ ██████████ ██ ██ ████████ ██████████ ███████████ ██ ███████ ███ ████ ████████ ████ ████████ ███ ███████████████
a
Belcher and Hu's █████ █████████ ██ ████████████ ████████ ████ ████ ██ ██████████████ ████ ███████ ███████ ████████ ██ ████████ ███ ████████████ ██ ███ ████████████ ██ █████████████
This might support a commercial application of someone’s research into DNA and semiconductors, but we’re looking to support an application of Belcher and Hu’s research into peptides and semiconductors.
b
For almost any █████████████ ████████ ████ ██ ████ ██ █ ████████ ████████ █████ ███ ████ █████ █████████████ █████████ ████ ████████ ██ ███ ████ ███ ███ █████ ██ ███████████ ███ ███
Belcher and Hu have already found peptides that can bind to and manipulate some semiconductor materials, but not necessarily all of them. If semiconductor materials are easily substituted for each other, it would mean we could build computer circuits using just the “peptide-friendly” materials that Belcher and Hu have found success with. This makes it more likely that their peptide approach to building semiconductors will be commercially feasible.
c
The number of ████████ ████ ████ ██ ███ █████████ ████████ ██ ████ ███████ ██ ██ ███████ ████ ███ ██████ ██ ████████ █████ ████████ ████ ████ ██ ███ █████████ █████████ ██████ ████ ██ ████ ██ ███ ████ █████
Irrelevant comparison. We don’t know how many peptides are needed that can bind to two different crystals at once, or many are needed that only bind to one crystal at a time.
d
The one billion ████████ ████ ███████ ███ ██ ████ ███ ██████ ██ ███ ███████ ██████ ██ █████ ████████ ███ ██████ ████ █████ ███ ██████ ██ ████████ ████ ████ ███ ██████ █████████████
This only tells us what happened in the past. It doesn’t give us any indication of what will or might happen in the future, and so it can’t support the prediction in the question stem. What’s the significance of (D)? Perhaps Belcher and Hu became more efficient in their search for useful peptides. Will the search continue to become more efficient, or less efficient? We don’t know. Alternatively, perhaps Belcher and Hu are running out of places to look for useful peptides. If so, this might make the prediction in the question stem less likely to come about. Ultimately, we don’t know why Belcher and Hu reduced the number of peptides they looked at, so (D) doesn’t tell us anything about what to expect in the future.
e
Expectations of continuing ████ █████ ██ ████████████ ███ ████████ ████ ███████ ███ ██ ████ █████ ██ ████ ██ ██████████████ ████ ██████ ██ ████████ ███ ██████ ██ ██████████ █████████████ ████████ ████████ ████ ███████ ████ ██ █████████████
This weakens the prediction in the question stem. If people expect that creating peptides for nanocircuit production will stay expensive, and if researchers are therefore less interested in working on building nanocircuits with peptides, it’s less likely that this approach will become commercially feasible.