Qbank Samples

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Hello!

Thanks for checking out our sample passages of the M Prep Qbank. We’ve selected a set of

three “average” passages – one from the Physical Sciences, one from Verbal Reasoning, and

one from Biological Sciences. These passages are neither the most difficult nor the easiest, but

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M Prep | Qbank Sample Passages

© 2014 Lee Simonov Services, LLC. All rights reserved. 1| 11

Physical Sciences

Question 1 – 5 are based on the following

passage

The decomposition of hydrogen bromide, HBr, is a

demonstration of how diverse environments can

influence chemical kinetics. Under certain

restricted conditions, the decomposition

proceeds in a single elementary reaction:

Reaction A

2HBr → H2 + Br2

Reaction A is exothermic, with standard activation

energy of 196 kJ/mol. In some cases, a metal

catalyst is introduced, and in the presence of

metal surfaces like gold and platinum, the

activation energies are more closelyapproximated at 115 kJ/mol and 72 kJ/mol,

respectively. Data collected from an experiment

with Reaction A are provided in Table 1.

Table 1. Comparison of reaction rates at various

HBr concentrations

Trial [HBr] at t = 0 Initial Rate (M/s)

1 2.0 2.0 x 10-3

2 3.0 4.0 x 10-3

3 4.0 8.0 x 10-3

4 6.0 1.6 x 10

-2

Under other conditions, HBr decomposition

proceeds through different reaction mechanisms.

For example, when exposed to certain

wavelengths of light, HBr undergoes

photochemical dissociation in three steps:

Reaction B

I) HBr + hf → H• + Br•

II) H• + HBr → H2 + Br•

III) 2Br• → Br2

Here, hf refers to the energy of a photon, with h

equal to 6.626 x 10-34 J•s (Planck's constant) and f

is the frequency of the light. Note that only

wavelengths less than 350 nm will provide

sufficient energy for the initiation of this reaction

when absorbed by HBr.

1. If Reaction A is a reversible reaction, an

increase in the temperature of the reaction

system would most likely produce:

I.

Lower activation energy

II.

Increase in the rate of the forward AND the

reverse reaction

III.

A change in the equilibrium concentration of

HBr

IV.

The neutralization of HBr (aq)

(A)

I only

(B)

II and III only

(C)

I, II, and III only

(D)

IV only

2. Based on the data in Table 1, what is the rateexpression for the decomposition of HBr shown in

Reaction A?

(A)

Rate = 2k

(B)

Rate = k[H][Br]

(C)

Rate = k[HBr]

(D)

Rate = k[HBr]2

3. Based on the surface catalysts described in the

passage, what entries best fit I, II, and III in the

graph, respectively?

(A)

Au, Pt, uncatalyzed

(B)

Pt, Au, uncatalyzed

(C)

Uncatalyzed, Au, Pt(D)

Uncatalyzed, Pt, Au





4. What type of light would cause the

photochemical decomposition of HBr to occur?

(A)

Infrared, 1 x 10-3

m to 7 x 10-7

m

(B)

Yellow - Green light, 6 x 10-7

m to 4.8 x 10-7

m

(C)

Blue - violet light, 4.8 x 10-7 m to 4 x 10-7 m

(D)

Ultraviolet, 4 x 10-7 to 5 x 10-8 m

5. In Reaction B, the II) step of the reaction would

be called the:

(A)

Propagation

(B)

Initiation

(C)

Perpetuation

(D)

Termination





Verbal Reasoning

Questions 6 – 12 are based on the following

passage:

Is there any knowledge in the world which is so

certain that no reasonable man could doubt it?This question, which at first sight might not seem

difficult, is really one of the most difficult that can

be asked. When we have realized the obstacles in

the way of a straightforward and confident

answer, we shall be well launched on the study of

philosophy - for philosophy is merely the attempt

to answer such ultimate questions, not carelessly

and dogmatically, as we do in ordinary life and

even in the sciences, but critically, after exploring

all that makes such questions puzzling, and afterrealizing all the vagueness and confusion that

underlie our ordinary ideas.

The philosopher who first brought prominently

forward the reasons for regarding the immediate

objects of our senses as not existing

independently of us was Bishop Berkeley (1685-

1753). The arguments employed are of very

different value: some are important and sound,

others are confused or quibbling. But Berkeleyretains the merit of having shown that the

existence of matter is capable of being denied

without absurdity, and that if there are any things

that exist independently of us they cannot be the

immediate objects of our sensations.

There are two different questions involved when

we ask whether matter exists, and it is important

to keep them clear. We commonly mean by

'matter' something which is opposed to 'mind',

something which we think of as occupying space

and as radically incapable of any sort of thought

or consciousness. It is chiefly in this sense that

Berkeley denies matter. He admits that there

must be something which continues to exist when

we go out of the room or shut our eyes, and that

what we call seeing the table does really give us

reason for believing in something which persists

even when we are not seeing it. But he thinks that

this something cannot be radically different in

nature from what we see, and cannot be

independent of seeing altogether, though it must

be independent of our seeing.

Such an argument, in my opinion, is fallacious;

and of course those who advance it do not put it

so shortly or so crudely. But whether valid or not,

the argument has been very widely advanced in

one form or another; and very many

philosophers, perhaps a majority, have held that

there is nothing real except minds and their ideas.

Such philosophers are called 'idealists'. When

they come to explaining matter, they either say,like Berkeley, that matter is really nothing but a

collection of ideas, or they say, like Leibniz (1646-

1716), that what appears as matter is really a

collection of more or less rudimentary minds.

Such questions are bewildering, and it is difficult

to know that even the strangest hypotheses may

not be true. Thus our familiar table, which has

roused but the slightest thoughts in us hitherto,

has become a problem full of surprisingpossibilities. The one thing we know about it is

that it is not what it seems. Philosophy, if it

cannot answer so many questions as we could

wish, has at least the power of asking questions

which increase the interest of the world, and

show the strangeness and wonder lying just

below the surface even in the commonest things

of daily life.

Adapted from The Problems of Philosophy by Bertrand Russell, 2009.





6. Which of the following lines best identifies the

thesis of the passage?

(A)

The arguments employed are of very different

value: some are important and sound, others

are confused or quibbling.

(B)

There are two different questions involved

when we ask whether matter exists, and it is

important to keep them clear.

(C)

Such an argument, in my opinion, is fallacious;

and of course those who advance it do not

put it so shortly or so crudely.

(D)

Philosophy, if it cannot answer so many

questions as we could wish, has at least the

power of asking questions.

7. The passage offers support for which of the

following positions?

(A)

Idealism is the only correct way of thinking

when it comes to philosophy.

(B)

Most of philosophy is fairly straightforward; it

is only complicated by humans.

(C)

Bishop Berkeley is important to remember

because of his many influential contributions

to philosophy.

(D)

The existence of matter depends on one's

perception of the object.

8. The information in the passage is sufficient to

answer which of the following questions?

(A)

What kind of goals does philosophy seek to

obtain?

(B)

What other schools of thought did Berkeley

disprove?

(C)

How is philosophy different from other

disciplines?

(D)

What arguments did other philosophers bring

up against Berkeley?

9. The example of Berkeley's table primarily

functions as a(n):

(A)

Introduction

(B)

Thesis

(C)

Example

(D)

Conclusion

10. In the context of the passage, "some"

(paragraph 2) most likely refers to the:

(A)

Reasons

(B)

Objects

(C)

Arguments

(D)

Existence

11. According to the passage, what kind of stance

does the author have pertaining to Berkeley's

ideas?

(A)

No interest

(B)

Agreement

(C)

Disagreement

(D)

Neutral

12. The author of the passage aims to:

(A)

Press upon the reader the uncertainty of

philosophy.

(B)

Examine the limits of philosophy.

(C)

Discuss whether the table is really a table.

(D)

Explain several different schools of

philosophy.





Biological Sciences

Questions 13 – 18 are based on the following

passage:

Figure 1 gives a standard subcloning for

transferring a DNA fragment (insert) from the

donor to the recipient plasmid. It involves three

steps:

1.

Releasing the insert from the donor plasmid

and its purification

2.

Digestion of the recipient plasmid

3.

Ligation of the insert into the recipient

ligations.

The release of insert is accomplished using

restriction enzymes that recognize specific

sequence of DNA and cleave the phosphatebackbone of the DNA molecule near that

sequence. Once digestion of the DNA fragments is

carried out with enzymes that generate

compatible ends ligation is carried out using DNA

ligases.

Amp and Neo indicated on the plasmids in the

figure are antibiotic markers that confer

resistance to ampicillin and neomycin

respectively. The ligated plasmids are

transformed into bacteria which are selectedusing appropriate antibiotics, depending on the

antibiotics markers on the plasmids. The

restriction digestion sites shown in the figure are

part of multiple cloning site, and are present only

as a single copy to facilitate ease of cloning.

Among these enzymes, the ones that do not

cleave the insert fragment (so that it can be

released intact) are used for cloning.

Figure 1. Digest procedure for subcloning DNA

from donor to recipient plasmid

13. If the ligation is carried out without purifying

it from the recipient vector, what is the best way

to select the donor plasmid with insert from the

colonies obtained after transformation?

(A)

Grow the transformed bacteria in medium

supplemented with no antibiotics.

(B)


supplemented with ampicillin.

(C)


supplemented with neomycin.

(D)


supplemented with tetracycline.





14. In an experiment the total size of donor

plasmid before digestion was about 5000 base

pairs. After the digestion with restriction enzymes

EcoRI and NotI, as shown above, it released an

insert of about 1500 base pairs. The insert was

then cloned into the donor plasmid. In order to

verify his information, the student then digested

the newly cloned vector that has the insert with

XhoI and NotI. He obtained three DNA fragments

of 100, 400 and 1000 base pairs in addition to the

4000 base pairs of the donor vector. Which of the

following statements is TRUE regarding the donor

vector carrying the insert?

(A)

NotI digestion by itself will also release all the

three fragments and the vector.

(B)

EcoRI digestion will release three fragments

and the vector.(C)

XhoI digestion by itself will release two

fragments and the vector.

(D)

EcoRI and NotI digestion will release 2

fragments and the vector.

15. Ligations are often difficult to achieve and

they are set up so as to maximize the probability

of success. Biologists have determined that a

mixture of DNA that has a 1:3 molar ratio of

vector to insert gives the best chance for success

with ligations. For the sake of simplicity suchcalculations often consider all bases of DNA to

have same molecular mass. If 100 nanograms of a

10 kb vector is used for cloning a 1 kb insert,

calculate the amount of insert that should be

used to obtain this ratio.

(A)

10 nanograms

(B)

30 nanograms

(C)

100 nanograms

(D)

300 nanograms

16. The example shown in the figure used two

enzymes to digest the two ends of the insert. If

the insert in the donor plasmid, is flanked at both

ends by EcoRI sites, EcoRI enzyme can be used to

release it from the donor vector. The recipient

vector, digested with EcoRI, can be used to clone

it. The EcoRI digestion at its target site GAATTC

and ligation is represented below.

Which of the following statements is FALSE under

these conditions?

(A)

The two ends of vector might ligate to

regenerate empty vectors.

(B)

Many vector molecules can ligate together to

give rise concatamers.

(C)

Many insert molecules can ligate together to

give rise to concatamers.

(D)

The cloned inserts from this ligation cannotbe released by EcoRI digestion.





17. Recognition sequences and cleavage sites

(arrows) of a few restriction enzymes are denoted

below:

If the DNA fragment A is digested with BamHI,

and the fragment B with BglII. Which of the

following statements is always correct?

(A)

A and B can be ligated and the product will be

digested by BamHI.

(B)


digested by DpnII.(C)


digested by all three enzymes.

(D)

A and B cannot be ligated.

18. Many enzymes leave an overhang on one of

the DNA strands after digestion. Some enzymes,

such as SmaI and EcoRV generate blunt ends with

no overhang. Ligation reactions that involve

fragments with blunt ends are often difficult. This

difficulty can be best explained by which of the

following?

(A)

Ligase enzyme requires these overhangs for

optimal activity.

(B)

Overhangs obviate the need of ligation.

(C)

Overhangs stabilize DNA ends facilitating

ligation.

(D)

Overhangs recruit DNA ligase facilitating

ligation.





Solutions

Physical Sciences

1. B When the temperature of a reaction system is increased, it will affect the kinetics and

thermodynamics of this reaction. Temperature affects the kinetics of all reactions, though not

necessarily to the same degree; a rise in temperature will increase the rate of any reaction. We will see ashift of the equilibrium based on the thermodynamics of the equation, but this is due to the kinetics of

one reaction being affected more than the kinetics of the other reaction. Thus II is correct. It is also

noted in the passage that the reaction is exothermic, so using Le Chatelier's principle, it can be predicted

that the reaction will shift to the left and increase the equilibrium concentration of HBr. This is

described in III, making it correct. Only catalysts can lower activation energies, making I incorrect. IV is

incorrect as we see there will be an increase, not a decrease in the concentration of HBr.

2. D The rate law can be determined by comparing different trials, and how any changes to the initial

concentration of the reactant affect the rate of the reaction. It is possible to use any set of trials, but

usually easiest to compare, for example, Trials 1 and 3. The concentration of [HBr] increases by a factor

of 2, while the reaction rate increases by a factor of 4. Solving 2

x

= 4; x = 2, indicating that the rate issecond order. This is the option in (D), where Rate = k[HBr]

2. Note that for elementary reactions, you

can simply use the coefficients of the reactants to directly write the rate law.

3. C These scenarios can be distinguished by the different energies of activation. The uncatalyzed

reaction would have the greatest energy of activation - the role of a catalyst is to lower this value so that

the reaction can proceed more readily. Between the two catalysts, it is stated that gold drops the

energy of activation to 115 kJ/mol, while platinum lowers it to 72 kJ/mol. So, the "energy hump" of

platinum would be lower than gold.

4. D The passage states that the wavelengths of light that can initiate this reaction are less than 350

nm. Looking at the list of options, they are in meters instead of nanometers, so the values have to be

evaluated by a shift of 10-2. Only the last option, ultraviolet, falls in the right window of wavelengths, is

less than 350 nm. Remember that the amount of energy is inversely related to the wavelength.

5. A Radical mechanisms typically have 3 steps: Initiation (I), Propagation (II), Termination (III).

Perpetuation is not a word used to describe a step in this process.

Verbal Reasoning

6. D (D) is the correct answer because it is the only choice that includes the general ideas and

arguments put forward in the passage. The passage introduces the nature of philosophy, then goes on

to discuss one facet of philosophy as an example, and then concludes with the idea that philosophy isn't

an exact science and has other purposes. (D), being in the conclusion, is the only summarizing thought

that carries the weight of the passage. (A), (B), and (C) are all incorrect because they each deal with anindividual part of the passage rather than the passage as a whole. As a 'thesis,' the correct statement

should be similar to an umbrella thought from which more specific thoughts are mentioned. (A), (B), and

(C) are the more specific thoughts under the umbrella, which means that they cannot be the thesis

itself.





7. D (D) is the correct answer because paragraphs 2 and 3 discuss the nature of matter and how it

relates to thought. In paragraph 2, the author states that Berkeley is able to deny matter because of

one's perception in its existence. (A) is incorrect because the author argues against idealism as a perfect

philosophy in paragraph 4. (B) is incorrect because the point of the passage is to discuss how many

possibilities there are in philosophy (paragraph 5). (C) is incorrect because the author only discusses one

way Berkeley has contributed to philosophy; the claim that Berkeley contributed many influential views

is thus false.

8. A (A) is the correct answer because the passage argues that philosophy aims to "ask questions" and

"show the strangeness and wonder... even in the commonest things of daily life" (paragraph 5). This

would be sufficient to answer the question posed in (A). (B) is incorrect because the only school of

thought that is mentioned is idealism, which means that it would be impossible for Berkeley to have

disproved any other schools. (C) is incorrect because the passage only concerns itself with the study of

philosophy and is not concerned with other disciplines such as mathematics or psychology. (D) is

incorrect because Berkeley and Leibniz are the only two philosophers brought up in the subject matter,

and both are idealists. Thus, there are no philosophers that were used to argue against Berkeley's ideas.

9. C (C) is the correct answer because Berkeley's table is used an example to demonstrate thestrangeness that philosophy is capable of ("such questions are bewildering, and it is difficult to know

that even the strangest hypotheses may not be true," paragraph 5). The passage opens with an

introduction of philosophy as a discipline, thus rendering (A) incorrect. Berkeley's table also cannot be

the thesis because the thesis of the passage has to do with the nature of philosophy itself. It also cannot

work as a conclusion because the main point of the passage is, again, the nature of philosophy. Thus,

Berkeley's table is then too specific to function as either a thesis or a conclusion. This would mean that

both (B) and (D) are incorrect.

10. C (C) is the correct answer. The word 'some' describes an idea that would be either important and

sound or confused or quibbling. The colon before 'some' indicates that 'some' is being used to list

separate mini-ideas of the bigger idea that 'some' is referring to. Because 'arguments' is the only nounbefore the colon, (C) is the correct answer. (A), (B), and (D) are all incorrect because they each exist

outside the context of the sentence and the colon that defines 'some'.

11. C (C) is the correct answer because the author declares Berkeley's argument to be fallacious

(meaning to have flaws), which means that the author does not agree wholeheartedly with Berkeley's

ideas. (A) and (D) are incorrect because, by declaring Berkeley's argument as fallacious, the author

actively forms an opinion and no longer remain disinterested or neutral. (B) is also incorrect because the

author seeks to go against Berkeley's ideas, meaning that the author in fact does not agree with

Berkeley.

12. A (A) is the correct answer because first and last paragraphs focus on the "vagueness,"

"confusion," "bewildering" nature, and "possibilities" of philosophy. By opening and ending with such

open-ended terms, the author seeks to draw an impression of how ambiguous and unlimited philosophy

can be in terms of possibilities. (B) is incorrect because of said possibilities; by admitting that philosophy

can be "full of surprising possibilities," the author inherently states that there are no definable limits to

the study of philosophy. (C) is incorrect because the table is just an example to help establish the

author's main claim, and is not intended to be the main claim itself. (D) is incorrect because only

idealism was mentioned as an example of a school of thought and none others.





Biological Sciences

13. C Since the insert was not purified after digestion, the bacteria transformed can contain either the

donor or recipient plasmids. These bacteria can be selected in media containing appropriate antibiotics.

If grown without antibiotics all the bacteria will grow irrespective of the presence of plasmid and this is

not useful for obtaining the cloned plasmid. Both the donor and recipient plasmids contain ampicillin

resistance markers and the bacteria containing either of them will grow if selected with ampicillin.

Neomycin can be used here because only the recipient plasmid contains its selection marker.

Tetracycline cannot be used because the donor plasmid has no suitable resistance marker and hence it

will kill the bacteria that we are interested in.

14. C As described in the passage, the restriction sites marked on the plasmids are unique and found in

one copy on the plasmid DNA. This means that if a unique enzyme releases multiple fragments from the

plasmid it can be only due to presence of its target sites in the insert. Here EcoRI and NotI were already

used for cloning the insert into recipient plasmid. Hence they cannot cleave inside the insert and will not

release 3 fragments. By themselves either of them will not release any DNA fragment from the plasmid

since they can digest only at one end of the insert. EcoRI and NotI together will release only one

fragment, which is the complete insert, since they were used in the cloning. Here the answer is that XhoI

by itself will release 2 fragments because when used in combination with NotI (which digests one end ofthe insert) it released 3 fragments. Since it is also a unique enzyme (and hence will cut the plasmid

backbone only once), the only explanation is that it digests the insert. One of the possible arrangements

of the restriction sites are shown below.

15. B The formula, derived from simple ratios is (kb of insert / kb of vector) x ng of vector x 3. This will

give 30 nanograms of insert. Since mass of insert DNA is one tenth of the vector mass (here we use the

approximation that all bases have same molecular mass), equimolar amounts can be obtained using one

tenth of the amount of vector. For a ratio of 1:3 (vector:insert), three fold of this value is used.

16. D As shown in the figure EcoRI-digested inserts can ligate to regenerate EcoRI restriction sites and

they can be cleaved by EcoRI again. When the DNA fragments are all digested with EcoRI, they can ligate

to form concatamers, and the plasmid molecules can religate without inserts. In practice, this can be

avoided by dephosphorylating the vectors so that they cannot ligate with themselves or concatamerize

vector molecules.





17. B The three enzymes given here have very similar recognition sequences. All three will generate

identical (3'-CTAG-5') DNA overhangs. Hence A and B fragments can be ligated together. However, the

ligated product will not be compatible for digestion with either BamHI or BglII since its sequence will be

different from either of their target sites and will have the following structure:

. . . GGATCT. . .

. . . CCTAGA. . .

Since DpnII recognized only the core 4 bases (GATC), it will be able to digest this hybrid DNA fragment

formed by ligating A and B.

18. C Ligase functions independent of DNA structure. If there are compatible overhangs the two

fragments of DNA can form hydrogen bonds at that region. This will facilitate formation of double

strands at the cleaved site, stabilizing them and increasing the probability of ligation of the two

fragments. This is not the case with blunt ends that have no overhangs. These ends are not stabilized,

making ligation difficult to achieve.

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