Competition to make computer chips smaller and, consequently, faster

Question

This passage was adapted from an article published in 2000.

Competition to make computer chips smaller and,
consequently, faster and more efficient has driven a
technological revolution, fueled economic growth, and
rapidly made successive generations of computers
  (5)   obsolete. Yet at the current rate of progress this march
toward miniaturization will hit a wall by about 2010—
for many, an unthinkable prospect. The laws of physics
dictate that, with current methods, properly functioning
transistors—the electronic devices that make up
  (10)   computer chips—cannot be made smaller than 25
nanometers (billionths of a meter). In living cells,
however, natural chemical processes efficiently and
precisely produce extremely complex structures below
this size limit, so there may be hope of using some such
  (15)   processes to yield tiny molecules that can either
function like transistors or be induced to combine with
other materials in carefully controlled ways to construct
whole nanocircuits. Much current research is aimed at
harnessing DNA to this end, but materials chemist
  (20)   Angela Belcher and physicist Evelyn Hu are
investigating a different molecular pattern maker:
peptides, amino acid chains that are shorter than
proteins.

The project grew out of Belcher’s doctoral
  (25)   research on abalone. Her research group discovered in
the mid-1990s that a specific peptide causes calcium
carbonate to crystallize into the structure found only in
the tough abalone shell. From that discovery, Belcher
and Hu, Belcher’s postdoctoral adviser at the time,
  (30)   realized that if they found peptides able to direct the
crystal growth of the semiconductor materials that
form transistors, they might have a tool for building
nanoscale electronics. However, no known peptide was
able to bind to semiconductor materials to cause the
  (35)   development of particular crystalline structures as
some peptides did with calcium carbonate. So Belcher,
Hu, and their colleagues grew a random assortment of one
billion different peptides and tested whether any of
them bound to silicon, gallium arsenide, or indium
  (40)   phosphide crystals—three widely used semiconductor
materials. They found a few peptides that not only
bound exclusively to one of the crystals in the
experiment but also latched onto a particular face of the
crystal. Through a process resembling accelerated
  (45)   evolution, they developed additional related
peptides from those that had the initially promising
characteristics.

Hu says that in order to use such a method to
assemble a set of circuit-building tools it would be
  (50)   necessary to identify many additional organic
compounds that bind to circuit-component materials.
The group is making progress on that quest. As they ,
have expanded their targets to 20 more semiconductor
materials, their cache of crystal-manipulating peptides
  (55)   has ballooned into the hundreds. They are also
designing new peptides that bind to two different
crystals at once, acting as a daub of glue. It will take
that kind of finesse at the nanoscale to produce self
assembling circuits.    1 
 1. Which one of the following most accurately expresses the main point of the passage?

(A) Although preliminary results suggest that Belcher and Hu's research on peptides and semiconductors could result in a breakthrough in the miniaturization of computer chips, enough obstacles remain to make such an outcome unlikely.
(B) Advances in computer chip speed and efficiency beyond the year 2010 may depend on the outcome of various current research projects, including that conducted by Belcher and Hu, which focus on using peptides to bind different crystals together.
(C) Belcher and Hu's research on the abilities of some peptides to bind to semiconductor materials indicates that peptides might eventually be applied to the production of computer chips with transistors smaller than the lower limit set by current methods.
(D) Belcher and Hu's discovery of peptides that cause the development of a particular crystalline structure in a natural biological context suggests that semiconductor materials might bind to biological compounds.
(E) The application of Belcher's work on abalone to the world of semiconductors shows that pure scientific research can have unexpected practical repercussions.

2 
 2. The words "that kind of finesse" (final sentence of the passage) refer primarily to

(A) the ability to translate abstract, theoretical concepts in computer design into concrete applications
(B) the creativity that was necessary to apply knowledge gained from DNA research to molecular pattern makers other than DNA the development of sophisticated methods of
(C) observing the behavior of crystalline structures that are both extremely tiny and extremely complex
(D) the ability to differentiate peptides that interact chemically with at least one semiconductor material from very similar peptides that do not interact with any such materials
(E) the ability of researchers to manipulate organic compounds in ways that satisfy very specific circuit-construction needs

3 
 3. Which one of the following statements about the peptides that Belcher and Hu tested in relation to semiconductors can be most reasonably inferred from the passage?

(A) At least some of them did not previously exist in nature.
(B) At least one of them was found to bind to three different semiconductor compounds.
(C) At least some of them were tested in relation to silicon but not in relation to gallium arsenide.
(D) At least one of them was in use in. the computer chip industry prior to Belcher and Hu's research.
(E) Other researchers had previously tested at least some of them for possible reactions with semiconductor materials other than silicon,. gallium arsenide, and indium phosphide.

4 
 4. Which one of the following situations involving volatile oils is most analogous to the situation involving peptides that is presented in the passage?

(A) A group of researchers, whose experimentation has focused on the chemical properties of certain synthetic volatile oils, abandons that line of inquiry on receiving a grant to study whether certain species of trees contain acids that could have antiviral properties in human medical applications.
(B) A group of researchers extracts several volatile oils from the leaves of certain species of trees and, while testing each of the oils to determine whether it has antifungal properties that could make it useful in human medical applications, they discover that one of the oils is a powerful insecticide.
(C) A group of researchers synthesizes several volatile oils that, when combined, are found to be useful as a fungicide on fruit trees. Through further experimentation, they find that this same combination of oils has antiviral properties in human medical applications.
(D) A group of researchers observes that a volatile oil contained in an antifungal product used on fruit trees can cause mutations in the trees. As a result, they launch a research project to determine whether similar oils that are used in human medical applications might cause genetic damage.
(E) A group of researchers, noting that a volatile oil secreted by a certain species of tree protects it from a type of fungal infection, synthesizes several similar oils and tests them for possible antibacterial activity that might make them useful in human medical applications.

5 
 5. The primary role of the first two sentence We passage is to help the reader understand

(A) why research of the sort done by Belcher and Hu was not previously undertaken by other researchers
(B) the purpose and importance of the research that Belcher and Hu have undertaken
(C) the skepticism with which some members of the scientific community have greeted Belcher and Hu's research
(D) a commonly held viewpoint against which Belcher and Hu's research is directed
(E) a hypothesis that Belcher and Hu's research is designed to test

6 
 6. The passage most strongly supports which one of the following?

(A) Some peptides that bind to gallium arsenide also bind to indium phosphide.
(B) Researchers besides Belcher and Hu and their colleagues have studied the possibility of using peptides in the assembly of nanocircuits.
(C) Neither Belcher nor Hu has done major scientific research on organic compounds other than peptides.
(D) Silicon, gallium arsenide, and indium phosphide are not the only semiconductor materials to which peptides have been found to bind.
(E) Peptides have been used in industrial applications that are not related to semiconductors.

7 
 7. Which one of the following, if true, lends the most support to a prediction of an eventual commercial application of Belcher and Hu's research into peptides and semiconductors?

(A) Belcher and Hu's early successes in synthesizing peptides that bind to semiconductors have sparked renewed interest in possible DNA applications in the construction of nanocircuits.
(B) For almost any semiconductor material that is used in a computer circuit, there are many other semiconductor materials that function in the same way and could be substituted for it.
(C) The number of peptides that bind to two different crystals at once appears to be smaller than the number of peptides that, although they bind to two different crystals, cannot bind to both at the same time.
(D) The one billion peptides that Belcher and Hu grew and tested in the initial stages of their research was nearly four times the number of peptides they grew and tested subsequently.
(E) Expectations of continuing high costs of synthesizing the peptides that Belcher and Hu have found to bind to semiconductors have tended to restrict the number of scientists contemplating possible research into peptide uses in nanocircuits.

Sajjad1994 · Answer

Explanation

1. Which one of the following most accurately expresses the main point of the passage?

Explanation

(A) Although preliminary results suggest that Belcher and Hu's research on peptides and semiconductors could result in a breakthrough in the miniaturization of computer chips, enough obstacles remain to make such an outcome unlikely.

This option suggests that the research conducted by Belcher and Hu could potentially lead to a breakthrough in miniaturizing computer chips. However, it also states that there are enough obstacles remaining, making the likelihood of such an outcome unlikely. While the passage does mention obstacles and challenges, it does not provide information about the likelihood of a breakthrough. Therefore, this option goes beyond what the passage presents and is not the main point of the passage.

(B) Advances in computer chip speed and efficiency beyond the year 2010 may depend on the outcome of various current research projects, including that conducted by Belcher and Hu, which focus on using peptides to bind different crystals together.

This option suggests that the future advances in computer chip speed and efficiency could depend on research projects, including Belcher and Hu's research on using peptides to bind different crystals together. While the passage discusses the potential of peptides in miniaturizing computer chips, it does not explicitly mention their impact on advances beyond 2010 or their role in binding different crystals together. Therefore, this option extends the scope of the passage and is not the main point presented.

(C) Belcher and Hu's research on the abilities of some peptides to bind to semiconductor materials indicates that peptides might eventually be applied to the production of computer chips with transistors smaller than the lower limit set by current methods.

This option accurately captures the main point of the passage. The passage discusses Belcher and Hu's research on peptides and semiconductor materials, highlighting that they have discovered peptides that can bind exclusively to semiconductor materials and direct the crystal growth. It suggests that this research indicates the potential application of peptides in producing computer chips with transistors smaller than the current limits. This aligns with the main focus of the passage and the potential breakthrough in miniaturization.

(D) Belcher and Hu's discovery of peptides that cause the development of a particular crystalline structure in a natural biological context suggests that semiconductor materials might bind to biological compounds.

This option focuses on the discovery of peptides by Belcher and Hu and suggests that it indicates the possibility of semiconductor materials binding to biological compounds. While the passage mentions the discovery of peptides and their ability to direct crystal growth in a natural biological context, it does not specifically discuss the binding of semiconductor materials to biological compounds. Therefore, this option goes beyond the information provided in the passage and is not the main point presented.

(E) The application of Belcher's work on abalone to the world of semiconductors shows that pure scientific research can have unexpected practical repercussions.

This option suggests that the application of Belcher's work on abalone to the field of semiconductors demonstrates the unexpected practical repercussions of pure scientific research. While the passage mentions Belcher's research on abalone as the starting point for her work with Hu, it does not explicitly discuss the broader implications of pure scientific research. Therefore, this option goes beyond the information provided in the passage and is not the main point presented.

Answer: C

Sajjad1994 · Answer

Explanation

3. Which one of the following statements about the peptides that Belcher and Hu tested in relation to semiconductors can be most reasonably inferred from the passage?

Explanation

(A) At least some of them did not previously exist in nature.

This statement can be reasonably inferred from the passage. It is mentioned that Belcher, Hu, and their colleagues grew a random assortment of one billion different peptides to test their binding abilities to semiconductor materials. This implies that these peptides were synthesized or created in the laboratory and may not have existed in nature before.

(B) At least one of them was found to bind to three different semiconductor compounds.

This statement cannot be reasonably inferred from the passage. The passage mentions that the researchers found peptides that bound exclusively to one crystal in the experiment but does not provide information about any peptide binding to multiple semiconductor compounds.

(C) At least some of them were tested in relation to silicon but not in relation to gallium arsenide.

This statement cannot be reasonably inferred from the passage. The passage mentions that the researchers tested whether any of the peptides bound to silicon, gallium arsenide, or indium phosphide crystals. However, it does not specify whether any peptide was tested exclusively with silicon but not gallium arsenide.

(D) At least one of them was in use in the computer chip industry prior to Belcher and Hu's research.

This statement cannot be reasonably inferred from the passage. The passage does not provide any information suggesting that any of the tested peptides were in use in the computer chip industry prior to Belcher and Hu's research.

(E) Other researchers had previously tested at least some of them for possible reactions with semiconductor materials other than silicon, gallium arsenide, and indium phosphide.

This statement cannot be reasonably inferred from the passage. The passage does not mention other researchers testing the peptides for reactions with semiconductor materials other than silicon, gallium arsenide, and indium phosphide.

Answer: A

Sajjad1994 · Answer

Explanation

4. Which one of the following situations involving volatile oils is most analogous to the situation involving peptides that is presented in the passage?

Explanation

(A) A group of researchers, whose experimentation has focused on the chemical properties of certain synthetic volatile oils, abandons that line of inquiry on receiving a grant to study whether certain species of trees contain acids that could have antiviral properties in human medical applications.

This option describes researchers who shift their focus from studying synthetic volatile oils to investigating the antiviral properties of acids in tree species. It is not directly analogous to the peptide research discussed in the passage, as it involves a change in research direction rather than a continuation of research on a specific substance.

(B) A group of researchers extracts several volatile oils from the leaves of certain species of trees and, while testing each of the oils to determine whether it has antifungal properties that could make it useful in human medical applications, they discover that one of the oils is a powerful insecticide.

In this situation, researchers extract volatile oils from tree leaves and test them for antifungal properties. During the testing process, they unexpectedly discover that one of the oils is a potent insecticide. While there is an element of unexpected discovery in both the peptide research and this situation, the focus on antifungal and insecticidal properties makes it less directly analogous to the peptide research.

(C) A group of researchers synthesizes several volatile oils that, when combined, are found to be useful as a fungicide on fruit trees. Through further experimentation, they find that this same combination of oils has antiviral properties in human medical applications.

This option describes researchers who synthesize volatile oils and find that a specific combination of these oils functions as a fungicide on fruit trees. Subsequently, they discover that the same combination of oils also exhibits antiviral properties in human medical applications. While there are parallels in terms of experimentation and unexpected discoveries, the focus on fungicidal and antiviral properties deviates from the focus on semiconductor materials in the peptide research.

(D) A group of researchers observes that a volatile oil contained in an antifungal product used on fruit trees can cause mutations in the trees. As a result, they launch a research project to determine whether similar oils that are used in human medical applications might cause genetic damage.

This option describes researchers who notice that a volatile oil in an antifungal product for fruit trees induces mutations in the trees. Consequently, they initiate a research project to investigate whether similar oils used in human medical applications could also cause genetic damage. While the observation of the effects of the volatile oil is somewhat analogous to the peptide research, the focus on genetic damage diverges from the focus on binding to semiconductor materials.

(E) A group of researchers, noting that a volatile oil secreted by a certain species of tree protects it from a type of fungal infection, synthesizes several similar oils and tests them for possible antibacterial activity that might make them useful in human medical applications.

This option is the most analogous to the peptide research described in the passage. It involves researchers who, based on the observation of a volatile oil's protective properties in a tree species, synthesize similar oils and conduct tests to determine their antibacterial activity. This aligns with the peptide research, where peptides are grown and tested for their ability to bind to semiconductor materials. The similarity lies in the process of synthesizing similar substances and exploring their potential applications. Therefore, option (E) is the most reasonable analogy to the situation involving peptides in the passage.

Answer: E

Sajjad1994 · Answer

Explanation

5. The primary role of the first two sentence We passage is to help the reader understand

Explanation

(A) why research of the sort done by Belcher and Hu was not previously undertaken by other researchers

Option (A) suggests that the primary role of the first two sentences is to explain why other researchers have not previously conducted research similar to Belcher and Hu's work. However, the passage does not provide any information or reasons regarding why other researchers have or have not undertaken this type of research. The focus of the passage is on Belcher and Hu's research itself rather than comparing it to the work of other researchers. Therefore, option (A) is not supported by the passage.

(B) the purpose and importance of the research that Belcher and Hu have undertaken

Option (B) correctly identifies the purpose and importance of Belcher and Hu's research as the primary role of the first two sentences. The passage discusses the competition to make computer chips smaller and more efficient, and it establishes that the current methods are reaching a limit due to the laws of physics. This sets the stage for introducing Belcher and Hu's research, which aims to explore alternative approaches using peptides to overcome the limitations. The purpose and importance of their research is to potentially revolutionize nanoscale electronics and address the challenges faced in computer chip miniaturization. Therefore, option (B) is supported by the passage and is the correct answer.

(C) the skepticism with which some members of the scientific community have greeted Belcher and Hu's research

Option (C) suggests that the primary role of the first two sentences is to convey the skepticism of some members of the scientific community towards Belcher and Hu's research. However, the passage does not provide any information about skepticism or opposition from the scientific community towards their work. The focus of the passage is on presenting the limitations in current methods and the potential of using peptides for nanoscale electronics. Therefore, option (C) is not supported by the passage.

(D) a commonly held viewpoint against which Belcher and Hu's research is directed

Option (D) proposes that the primary role of the first two sentences is to present a commonly held viewpoint that Belcher and Hu's research aims to challenge. However, the passage does not provide information about any specific commonly held viewpoint that their research is directed against. The focus of the passage is on the challenges and limitations in computer chip miniaturization and the potential of peptides as an alternative approach. Therefore, option (D) is not supported by the passage.

(E) a hypothesis that Belcher and Hu's research is designed to test

Option (E) suggests that the primary role of the first two sentences is to present a hypothesis that Belcher and Hu's research is designed to test. However, the first two sentences do not directly present a hypothesis. They provide background information about the competition to make computer chips smaller and highlight the limitations of current methods. The hypothesis being tested is not explicitly stated in those sentences. The focus of the passage is on the potential of peptides for nanoscale electronics rather than explicitly testing a hypothesis. Therefore, option (E) is not supported by the passage.

In summary, option (B) is the most accurate explanation of the primary role of the first two sentences in the passage.

Answer: B

nikitathegreat · Answer

GMATNinja

B) Advances in computer chip speed and efficiency beyond the year 2010 may depend on the outcome of various current research projects, including that conducted by Belcher and Hu, which focus on using peptides to bind different crystals together.
(C) Belcher and Hu's research on the abilities of some peptides to bind to semiconductor materials indicates that peptides might eventually be applied to the production of computer chips with transistors smaller than the lower limit set by current methods.

I am confused with option choices B and C for the 1st ques - primary purpose.
Can we reject ans choice B because the outcome for Belcher and Hu that focussed on using peptides to bind different crystals together weas already determined?

thelastskybender · Answer

I found following explanation from the powerscore forum useful: 
"
 
 B has the wrong focus - it's framed as about what computer chip tech depends on; the passage, rather, seems to be focused primarily on Belcher and Hu's research, which may find an application in transistors. This difference seems subtle, but maybe somebody could tell me whether I'm onto something here. The passage does say say that miniaturization "will hit a wall" by about 2010, so it's not a big leap to say that future progress will depend on serious innovation like the projects mentioned at the end of paragraph 1. This was the only flaw I noticed initially, so I failed to eliminate B. 
 B describes Belcher and Hu's research as being about "  different crystals together," whereas C describes it as "on the abilities of some peptides to bind to semiconductor materials." I think there's a slight difference between binding different crystals together and peptides binding to semiconductor materials; the latter is more specific and more accurate to the passage's focus. About specificity: semiconductors are a type of crystal, but semiconductor materials and crystals are not synonymous; diamonds, for example, are non-conductive crystals. And about accuracy: binding different semiconductor materials together is only discussed in the penultimate sentence of the final paragraph, whereas binding peptides to semiconductors is the entire 2nd paragraph and part of the 3rd.  
"

GMATNinja · Answer

Question 1 
 
This is a tough one. The big difference between the two is that (B) makes it sound as though the passage is about multiple research projects, one of which is by Belcher and Hu.

The only problem? No one else's research is mentioned. Belcher and Hu aren't one of many here. They're the whole show.

(C) makes it clear that the passage is primarily about Belcher and Hu's research and how that research might be applied to the problem of designing smaller transistors. So (C) is a bit better.

I hope that helps!

Nipunh · Answer

Hi experts!  GMATNinja ,  Sajjad1994 ,  GMATNinjaTwo 
Can you please explain Q2, I am stumped on this one!

Also I am able to get all the questions correct except q2, but it took me 20 mins to solve it... what exactly should be my next step, as this a regular occurence for me (the accuracy and time mgmt remains almost the same at this difficulty level)

GMATNinja · Answer

Question 2 
 
Remember that you do not need to get EVERY question right to get a great score. If you're wasting lots of time chasing the questions that you feel LEAST comfortable with (like Q2 in this passage), then you probably need to do a better job letting go when you're stumped or not feeling confident about something. If you had taken, say, 15 minutes and missed two questions instead of just one, that would probably have been a better result -- you don't want a couple tough questions to completely throw off your timing.

With that disclaimer in mind, let's take a look at question 2.

The passage talks about developing peptides (a type of "molecular pattern maker") to manipulate the crystal growth of semiconductor materials. The final paragraph then gives an example of newly developed peptides that can act as a daub of glue.

Referring to the glue example, here's the final sentence:

Again, this refers to the glue example, so "that kind of finesse" must refer to the finesse (precision) involved in manipulating organic compounds (like peptides) in order to achieve nanoscale construction. (Binding two things together to make something is an example of "construction" in this context.)

And that's the sort of thing researchers will need to do in order to achieve self-assembling circuits -- they'll need to create peptides that can interact with crystals in order to satisfy very specific construction needs, such as peptides that cause particular crystalline structures to develop or different crystals to bind together in specific ways.

The last sentence refers to the precision or finesse needed to manipulate peptides in order to build specific things at the molecular level, and that fits with choice (E).

gullyboy09 · Answer

Hi  GMATNinja , can you help me with the last question.

My concern with the given answer is that even if any semiconductor can be substituted by another, but we don't know if peptide would stick to it or not. For example, peptide p, works well with semiconductor A, but it might not work well with it's substitution B (maybe B does all the things that A does, but will peptide p work in the same way?) I might not have a complete understanding also, so maybe I am missing something.

egmat · Answer

Hi gullyboy09,

You've spotted a real constraint in the passage: each peptide binds  exclusively  to one crystal (and even to one face of it), so a peptide for material A tells us nothing about whether it works on material B. That part of your reasoning is correct.

The key is that choice  (B)  runs the logic in the opposite direction from the one you're worried about.

You're imagining this order:
1. The circuit  requires  material A.
2. We hope our peptide also happens to stick to A's replacement, B.

But  (B)  lets the researchers work the other way:
1. Start from the peptides they  already have  - say, a peptide that binds to material B.
2. Since "for almost any semiconductor material... there are many other materials that function the same way and could be substituted," they can simply build the circuit using B wherever A's  function  is needed.

So they never have to force a fixed material onto a peptide. Whatever material a peptide already binds to, there's an interchangeable material that fills the required role. That means their current, limited collection of peptides could be enough to actually assemble working circuits - which is exactly what a "commercial application" prediction needs. You don't need to find a peptide for every material; you pick the material to match the peptide you've got.

A simpler stand-in to lock it in:

You own a keyring with a few specific keys. You need to reach a certain room, and there are many doors that all open into that same room. You don't ask, "Will my key fit this one particular door?" You just walk to whichever door your key already opens.

Because the doors are interchangeable (they all reach the room), your existing keys are enough. Swap "key" for peptide and "door" for semiconductor material, and that's precisely why  (B)  supports the prediction - no peptide has to adapt to a substitute at all.

Answer: B

PaceMile · Answer

Can someone provide explanation for answer choice of question 7?

egmat · Answer

Hi PaceMile,

The key to Q7 is spotting the  obstacle  the passage sets up, and then seeing which choice knocks it down.

The obstacle in the passage

Two lines create the problem:

- Each promising peptide binds  exclusively to one  crystal - and even to "a particular face of the crystal" (lines  41 - 44 ).
- Hu says that to build a full toolkit, "it would be necessary to  identify many additional organic compounds  that bind to circuit-component materials" (lines  48 - 51 ).

So the catch is  specificity : a real circuit needs certain materials, and you'd need a matching peptide for every one of them. That's a lot of missing peptides - which is exactly what makes a  commercial  circuit look far off.

Why (B) is the answer

(B) says that for almost any semiconductor material, there are  many interchangeable materials  that do the same job. That flips the whole problem around:

- You  don't  have to find a peptide for each material the design calls for.
- You start from the peptides you  already  have, and simply build the circuit out of whatever materials those peptides happen to bind to.

Because the materials are swappable, the limited set of peptides Belcher and Hu already possess could be  enough  to assemble a working circuit - which is precisely what a "commercial application" prediction needs.

Why the others don't help

-  (A)  Boosts interest in a  rival  DNA approach - not the peptide route.
-  (C)  Compares counts of glue-type peptides - says nothing about viability.
-  (D)  Compares how many peptides were grown in each stage - irrelevant.
-  (E)  High costs and fewer researchers  weaken  the prediction.

A quick parallel to lock it in

Imagine you're assembling furniture and you own only  three  screwdriver bits. If every screw needed a different bit, you'd be stuck. But if  almost any screw can be swapped for one of the three types your bits already fit , then your small kit is suddenly enough to finish the job. That interchangeability - not a bigger toolkit - is what (B) supplies.

Answer: B

guddo · Answer

7. Which one of the following, if true, lends the most support to a prediction of an eventual commercial application of Belcher and Hu's research into peptides and semiconductors?

The passage says researchers are studying whether peptides can help build tiny circuit components below the normal transistor size limit.  For commercial use , it would help if peptides could bind in useful ways to materials used in actual computer circuits. The strongest support is evidence that there is flexibility in which semiconductor materials can be used.

(A) Belcher and Hu's early successes in synthesizing peptides that bind to semiconductors have sparked renewed interest in possible DNA applications in the construction of nanocircuits.

This does not support commercial application of Belcher and Hu’s peptide research. It shifts attention to DNA applications instead.

(B) For almost any semiconductor material that is used in a computer circuit, there are many other semiconductor materials that function in the same way and could be substituted for it.

This is correct. If many semiconductor materials can perform the same circuit function, then peptide-based research has a better chance of becoming commercially useful. Researchers would not need peptides to work with one exact material; they could use a  substitute semiconductor  that peptides can bind to.

(C) The number of peptides that bind to two different crystals at once appears to be smaller than the number of peptides that, although they bind to two different crystals, cannot bind to both at the same time.

This gives some technical detail, but it is not the strongest support for commercial application. It mainly says that simultaneous dual-binding peptides are less common than another type.

(D) The one billion peptides that Belcher and Hu grew and tested in the initial stages of their research was nearly four times the number of peptides they grew and tested subsequently.

This does not support commercial application. The number tested does not show that the research will become practically useful.

(E) Expectations of continuing high costs of synthesizing the peptides that Belcher and Hu have found to bind to semiconductors have tended to restrict the number of scientists contemplating possible research into peptide uses in nanocircuits.

This weakens commercial prospects. High expected costs and limited research interest make commercial application less likely.

Answer: (B)

Competition to make computer chips smaller and, consequently, faster

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Competition to make computer chips smaller and, consequently, faster

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