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Electromagnetic radiation from space constantly bombards the earth. Most wavelengths are absorbed by
the atmosphere; however, there are two "windows" of nonabsorption through which significant amounts of
radiation reach the ground. The first transmits ultraviolet and visible light, as well as infrared light or heat;
the second transmits radio waves. As a result, terrestrial organisms have evolved a number of pigments that interact with light in various ways: some capture light energy, some provide protection from light-induced damage, and some serve camouflage or signaling purposes.

Among these compounds are many conjugated polyenes, which play important roles as photoreceptors.
For every chemical compound, there are certain wavelengths of light whose quanta possess exactly the correct amount of energy to raise electrons from their ground state to higher-energy orbitals. For most organic compounds, these wavelengths are in the UV range. However, conjugated double bond systems stabilize the electrons, so that they can be excited by lower-frequency photons with wavelengths in the visible spectrum. Such a pigment, known as a chromophore, will then transmit the "subtraction color," a color complementary to the one absorbed. For instance, carotene, a hydrocarbon compound with eleven conjugated double bonds, absorbs blue light and transmits orange. The wavelength that is absorbed
generally increases with the number of conjugated bonds; rings and side-chains also affect wavelength.

Wavelength Color Subtraction Color
480 nm blue orange
580 nm yellow violet
680 nm red green

Among the many biological molecules that are affected by light is DNA, the genetic material of living
organisms. DNA absorbs ultraviolet light, and may be damaged by UVC (< 280 nm) and UVB (280-315
nm). UVA (315-400 nm) and visible light can actually repair light-induced damage to DNA by a process called photorepair. For this reason, UVA, which also stimulates tanning, was once considered beneficial.
However, there is now increasing evidence that UVA can damage skin.

Many crustaceans produce a blue or green caroteneprotein complex.

What is the most likely cause of the color change from green to orange when a lobster is boiled?

What happens to brain waves as an organism falls asleep?

TMS (tetramethylsilane) is commonly added to nuclear magnetic resonance (NMR) samples. It has a chemical shift which is upfield of most organic signals, and it gives a strong, sharp singlet peak and can be easily removed.

Why is TMS added to NMR samples?

Which of the following is equivalent to one Pascal of gas pressure?

A student was given a sample of an unknown liquid and asked to determine as much as possible about its structure. He was told that the compound contained only carbon, hydrogen, and oxygen, and had only one type of functional group. The student found its boiling point to be 206. Using mass spectroscopy, he determined its molecular weight to be 138 g/mol. Finally, he took the infrared spectrum of the compound, which is shown below.

From this spectrum, the student quickly reached a conclusion about the functional group. He then turned his attention to the fingerprint region of the compound, which generally has a complicated pattern of peaks that are determined by the structure of the hydrocarbon portion of a molecule. The student decided that the large peak at 750 cm-1 must indicate that this was a disubstituted aromatic compound.

The overlapping set of peaks near 3000 cm-1 includes one peak at 2850 cm-1.

What type of functional group could this indicate?

One of the basic principles of ecology is that population size is to some extent a function of available food resources. Recent field experiments demonstrate that the interrelationship may be far more complex than hitherto imagined. Specifically, the browsing of certain rodents appears to trigger biochemical reactions in the plants they feed on that help regulate the size of the rodent populations. Two such examples of phytochemical regulation (regulation involving plant chemistry) have been reported so far.
Patricia Berger and her colleagues at the University of Utah have demonstrated that instrumentality of 6- methoxybenzoxazolinone (6-MBOA) in triggering reproductive behavior in the mountain vole (Microtus montanus), a small rodent resembling the field mouse. 6-MBOA forms in young mountain grasses in response to browsing by predators such as voles. The experimenters fed rolled oats coated with 6-MBOA to non-breeding winter populations of Microtus. After three weeks, the sample populations revealed a high incidence of pregnancy among the females and pronounced swelling of the testicles among the males.
Control populations receiving no 6- MBOA revealed no such signs. Since the timing of reproductive effort is crucial to the short-lived vole in an environment in which the onset of vegetative growth can vary by as much as two months, the phytochemical triggering of copulatory behavior in Microtus represents a significant biological adaptation.
A distinct example is reported by John Bryant of the University of Alaska. In this case, plants seem to have adopted a form of phytochemical self-defense against the depredations of the snowshoe hare (Lepus americanus) of Canada and Alaska. Every ten years or so, for reasons that are not entirely understood, the Lepus population swells dramatically. The result is intense overbrowsing of early and mid-successional deciduous trees and shrubs. Bryant has shown that, as if in response, four common boreal forest trees favored by Lepus produce adventitious shoots high in terpene and phenolic resins which effectively discourage hare browsing. He treated mature, non-resinous willow twigs with resinous extracts from the adventitious shoots of other plants and placed treated and untreated bundles at hare feeding stations, weighing them at the end of each day. Bryant found that bundles containing only half the resin concentration of natural twigs were left untouched. The avoidance of these unpalatable resins, he concludes, may play a significant role in the subsequent decline in the Lepus population to its normal level.
These results suggest obvious areas for further research. For example, observational data should be reviewed to see whether the periodic population explosions among the prolific lemming (like the vole and the snowshoe hare, a small rodent in a marginal northern environment) occur during years in which there
is an early onset of vegetative growth; if so, a triggering mechanism similar to that found in the vole may be
involved.

Bryant's interpretation of the results of his experiment (lines 46?
8. depends on which of the following assumptions?

Which option is not an example of vertical social mobility?

Several techniques have been developed to determine the order of a reaction. The rate of a reaction cannot be predicted on the basis of the overall equation, but can be predicted on the basis of the rate-determining step. For instance, the following reaction can be broken down into three steps.

Step 1

(Slow)
Step 2

(fast)
Step 3

(fast)

Reaction 1
In this case, the first step in the reaction pathway is the rate-determining step. Therefore, the overall rate of the reaction must equal the rate of the first step, k1 [A] where k1 is the rate constant for the first step. (Rate constants of the different steps are denoted by kx , where x is the step number.)

In some cases, it is desirable to measure the rate of a reaction in relation to only one species. In a second-order reaction, for instance, a large excess of one species is included in the reaction vessel. Since a relatively small amount of this large concentration is reacted, we assume that the concentration essentially remains unchanged. Such a reaction is called a pseudo first-order reaction. A new rate constant, k', is established, equal to the product of the rate constant of the original reaction, k, and the concentration of the species in excess. This approach is often used to analyze enzyme activity.

In some cases, the reaction rate may be dependent on the concentration of a short-lived intermediate. This can happen if the rate-determining step is not the first step. In this case, the concentration of the intermediate must be derived from the equilibrium constant of the preceding step. For redox reactions, the

equilibrium can be correlated with the voltage produced by two half-cells by means of the Nernst equation.
This equation states that at any given moment:

Equation 1
When

Reaction 2
Note: R = 8.314 J/K-mol; F = 9.6485 x 104 C/mol.) In a test of the rate of Step 3 of Reaction 1, a solution is prepared containing a 0.1 M concentration of E and a 50 M concentration of C. The rate is calculated after the reaction has gone 50% to completion.
By what percent will the calculated rate differ from the true rate if we treat the reaction as pseudo first-order?

As Alice Echols went on to claim, "Nothing seems to conjure up the 1970s quite so effectively as disco.
Even at the time, critics remarked upon disco's neat encapsulation of that decade's zeitgeist. 'It must be clear by now to everyone with an ear or an eye that this era,' wrote journalist Andrew Kopkind in 1979, 'is already the Disco Years, whether it will be called by that name or not.' A former sixties radical, Kopkind was by turns fascinated, bemused, and appalled by the disco epoch, and he likely imagined that in years to come fellow cultural critics would share his interest. But the seventies have not loomed large in our national imagination, except perhaps as comic relief. For many Americans, these were the forgettable years.

That forgettability owes a lot to the 1960s, the outsized decade that dwarfs all others in recent memory.
The sixties will always be remembered for their audacity, whether found in the courage of civil rights protesters who put their bodies on the line or in those doomed but beautiful rock stars who tried breaking through to the other side. By contrast, the seventies seem the decade when nothing, or nothing good, happened - an era memorable for the country's hapless presidents, declining prestige, bad fashions, ludicrous music, and such over-the-top narcissism that Tom Wolfe dubbed it the 'Me Decade.' Before the decade was out, this narrative of decline had become routine. 'After the poetry of the Beatles comes the monotonous bass-pedal bombardment of Donna Summer,' huffed one New York Times writer in 1979. It is a measure of the era's persistent bad press that a recent book challenging this view carries the pleading title Something Happened.

As for the sixties, it doesn't matter how much silliness went down, we still invest those times with seismic significance. Take Joe Cocker's performance at Woodstock. His spasmodic thrashing about and his vocals, slurred to the point of incomprehensibility, are something of a joke today. Cringe-inducing though it may be, however, Cocker's performance is never made to stand in for the whole of the sixties. The sixties remain enveloped in the gauzy sentimentalism of what might have been. Yet the iconic image of John Travolta as dance-floor king Tony Manero in white polyester suit, arm thrust to the disco heavens, has come to symbolize the narcissistic imbecility and inconsequentiality of the disco years.

Were it not for the Rubaiyat, I, too, might well regard the seventies as a lamentable and regrettable period in American history. The Rubaiyat was, yes, a disco. It was located in the heart of sixtiesland: Ann Arbor, Michigan, the home of the University of Michigan and legendary incubator of radical activism. At the height of the seventies, the town's annual Hash Bash - a smoke-in to reform marijuana laws - was still going strong and so were its two food co-ops-one reform, the other orthodox when it came to selling white foods (that is, rice, sugar, and flour of the white variety). Ann Arbor also had bookstores galore, including the original, wonderful Borders Bookstore, and any number of hippie-ish restaurants and bars such as the Fleetwood Diner, the Del Rio, and the Blind Pig. Musically, it prided itself on its vintage music (it hosted one of the earliest blues festivals), but at heart it was a rock town besotted with Iggy Pop and the Stooges and Sonic's Rendezvous, a band fronted by Patti Smith's future husband, Fred Smith. Its leading music store, Schoolkids' Records, stocked disco, but never played it. All of this is to say that disco-averse Ann Arbor came close to providing something of a safe haven from glitterball culture.

The Rubaiyat was no red-velvet-rope disco where fashionista doormen determined who was sufficiently fabulous to gain entry. This would never have worked in a town where down jackets and army surplus were hardly an unusual sight. The club did have some pretensions to classiness, but the mismatched, sagging booths and bordello red defeated occasional efforts at upmarket sophistication. What the Rubaiyat did have were better-than-average speakers, a heterogeneous clientèle, and a weekend cover of three dollars."

Echols, A. (2011). Hot stuff: Disco and the Remaking of American Culture. New York: W. W. Norton.

What is the author's main argument in this passage about the public perception of disco?

The nuclei of certain unstable isotopes will spontaneously decay, producing a more stable nucleus and releasing a particle or quantity of energy. Alpha decay releases a helium nucleus, beta decay emits an electron, while gamma decay is the emission of a high energy photon. Each type of radioactive decay is characterized, in part, by the half-life of the radioactive material--the time required for half of the nuclei in a sample to undergo decay. Examples of such decays are shown in Figure 1.

Figure 1
A Geiger counter can be used to detect the decay of radioactive materials. A simple Geiger counter consists of a hollow metal cylinder with a wire along its axis. The cylinder is filled with low pressure argon gas and a high voltage difference is applied between the wire and the cylinder. When alpha, beta, or gamma radiation passes through the cylinder, it interacts with the gas particles and leads to the formation of ions which cause a discharge between the wire and the cylinder. The consequent current may be used to drive a speaker, producing the characteristic clicking sound of the Geiger counter each time a pulse of current occurs. The Geiger counter circuitry is shown in Figure 2.

Figure 2

The half-life of 32P is 14.28 days.

What fraction of an initially pure sample will have decayed after 28.56 days?

Alleles are created when a single gene undergoes several distinct mutations. These alleles may have
different dominance relationships with one another; for example, there are three alleles coding for the
human blood groups, the IA, IB, and i alleles. Both the IA and IB alleles are dominant to the i allele, but IA and IB are codominant to each other.

A multiple-allele system has recently been discovered in the determination of hair coloring in a species of

wild rat. The rats are found to have one of three colors: brown, red, or white. Let B = the gene for brown
hair; b = the gene for red hair; and w = the gene for white hair. The results from nine experimental crosses
are shown below. The males and females in Crosses 1, 2, and 3 are all homozygous for hair color.

Based on the experimental results, what is the genotype of the male in Cross 6?

One of the basic principles of ecology is that population size is to some extent a function of available food resources. Recent field experiments demonstrate that the interrelationship may be far more complex than hitherto imagined. Specifically, the browsing of certain rodents appears to trigger biochemical reactions in the plants they feed on that help regulate the size of the rodent populations. Two such examples of phytochemical regulation (regulation involving plant chemistry) have been reported so far.
Patricia Berger and her colleagues at the University of Utah have demonstrated that instrumentality of 6- methoxybenzoxazolinone (6-MBOA) in triggering reproductive behavior in the mountain vole (Microtus montanus), a small rodent resembling the field mouse. 6-MBOA forms in young mountain grasses in response to browsing by predators such as voles. The experimenters fed rolled oats coated with 6-MBOA to non-breeding winter populations of Microtus. After three weeks, the sample populations revealed a high incidence of pregnancy among the females and pronounced swelling of the testicles among the males.
Control populations receiving no 6- MBOA revealed no such signs. Since the timing of reproductive effort is crucial to the short-lived vole in an environment in which the onset of vegetative growth can vary by as much as two months, the phytochemical triggering of copulatory behavior in Microtus represents a significant biological adaptation.
A distinct example is reported by John Bryant of the University of Alaska. In this case, plants seem to have adopted a form of phytochemical self-defense against the depredations of the snowshoe hare (Lepus americanus) of Canada and Alaska. Every ten years or so, for reasons that are not entirely understood, the Lepus population swells dramatically. The result is intense overbrowsing of early and mid-successional deciduous trees and shrubs. Bryant has shown that, as if in response, four common boreal forest trees favored by Lepus produce adventitious shoots high in terpene and phenolic resins which effectively

discourage hare browsing. He treated mature, non-resinous willow twigs with resinous extracts from the adventitious shoots of other plants and placed treated and untreated bundles at hare feeding stations, weighing them at the end of each day. Bryant found that bundles containing only half the resin concentration of natural twigs were left untouched. The avoidance of these unpalatable resins, he concludes, may play a significant role in the subsequent decline in the Lepus population to its normal level.
These results suggest obvious areas for further research. For example, observational data should be reviewed to see whether the periodic population explosions among the prolific lemming (like the vole and the snowshoe hare, a small rodent in a marginal northern environment) occur during years in which there
is an early onset of vegetative growth; if so, a triggering mechanism similar to that found in the vole may be
involved.

The experiments described in the passage involved all of the following EXCEPT:

Each of the following are aspects of the McDonaldization of Society EXCEPT:

Which of the following molecules will stop being produced first when oxygen is no longer supplied to the cell?

The lining of the digestive tract and the respiratory tract develops from which germ layer?

I. Endoderm
II. Mesoderm
III. Ectoderm

Our sense of smell is arguably the most powerful of our five senses, but it also the most elusive. It plays a vital yet mysterious role in our lives. Olfaction is rooted in the same part of the brain that regulates such essential functions as body metabolism, reaction to stress, and appetite. But smell relates to more than physiological function: its sensations are intimately tied to memory, emotion, and sexual desire. Smell seems to lie somewhere beyond the realm of conscious thought, where, intertwined with emotion and experience, it shapes both our conscious and unconscious lives.

The peculiar intimacy of this sense may be related to certain anatomical features. Smell reaches the brain more directly than do sensations of touch, sight, or sound. When we inhale a particular odor, air containing volatile odiferous molecules is warmed and humidified as it flows over specialized bones in the nose called turbinates. As odor molecules land on the olfactory nerves, these nerves fire a message to the brain. Thus olfactory neurons render a direct path between the stimulus provided by the outside environment and the brain, allowing us to rapidly perceive odors ranging from alluring fragrances to noisome fumes.

Certain scents, such as jasmine, are almost universally appealing, while others, like hydrogen sulfide (which emits a stench reminiscent of rotten eggs), are usually considered repellent, but most odors evoke different reactions from person to person, sometimes triggering strong emotional states or resurrecting seemingly forgotten memories. Scientists surmise that the reason why we have highly personal associations with smells is related to the proximity of the olfactory and emotional centers of our brain.
Although the precise connection between emotion and olfaction remains a mystery, it is clear that emotion, memory, and smell are all rooted in a part of the brain called the limbic lobe.

Even though we are not always conscious of the presence of odors, and are often unable to either

articulate or remember their unique characteristics, our brains always register their existence. In fact, such a large amount of human brain tissue is devoted to smell that scientists surmise the role of this sense must be profound. Moreover, neurobiological research suggests that smell must have an important function because olfactory neurons can regenerate themselves, unlike most other nerve cells. The importance of this sense is further supported by the fact that animals experimentally denied the olfactory sense do not develop full and normal brain function.

The significance of olfaction is much clearer in animals than in human beings. Animal behavior is strongly influenced by pheromones, which are odors that induce psychological or behavioral changes and often provide a means of communicating within a species. These chemical messages, often a complex blend of compounds, are of vital importance to the insect world. Honeybees, for example, organize their societies through odor: the queen bee exudes an odor that both inhibits worker bees from laying eggs and draws drones to her when she is ready to mate. Mammals are also guided by their sense of smell. Through odors emitted by urine and scent glands, many animals maintain their territories, identify one another, signal alarm, and attract mates.

Although our olfactory acuity can't rival that of other animal species, human beings are also guided by smell. Before the advent of sophisticated laboratory techniques, physicians depended on their noses to help diagnose illness. A century ago, it was common medical knowledge that certain bacterial infections carry the musty odor of wine, that typhoid smells like baking bread, and that yellow fever smells like meat.
While medical science has moved away from such subjective diagnostic methods, in everyday life we continue to rely on our sense of small, knowingly or not, to guide us.

It can be inferred from the passage that the emotional element of human olfaction would be better understood through investigation into:

Which titration curve would be produced by titrating 25 mL of a 0.1 N weak base with a 0.1 N strong acid?

Many nutrients required by plants exist in soil as basic cations:

A soil's cation-exchange capacity is a measure of its ability to adsorb these basic cations as well as exchangeable hydrogen and aluminum ions. The cation-exchange capacity of soil is derived from two sources: small clay particles called micelles consisting of alternating layers of alumina and silica crystals, and organic colloids.

Replacement of + and + by other cations of lower valence creates a net negative charge within the inner layers of the micelles. This is called the soil's permanent charge. For example, replacement of an atom of aluminum by calcium within a section where the net charge was previously zero, as shown below, produces a net charge of ?, to which other cations can become adsorbed.

Figure 1

A pH-dependent charge develops when hydrogen dissociates from hydroxyl moieties on the outer surfaces

of the clay micelles. This leaves negatively-charged oxygen atoms to which basic cations may adsorb.
Likewise, a large pH-dependent charge develops when hydrogen dissociates from carboxylic acids and phenols in organic matter.
In most clays, permanent charges brought about by substitution account for anywhere from half to nearly all of the total cation-exchange capacity. Soils very high in organic matter contain primarily pH-dependent charges. In a research study, three samples of soil were leached with a 1 N solution of neutral KCl, and the displaced A13+ and basic cations measured. The sample was then leached again with a buffered solution of BaCl2 and triethanolamine at pH 8.2, and the displaced H+ measured. Table 1 gives results for three soils tested by this method.
Table 1

Due to the buffering effect of the soil's cation exchange capacity, just measuring the soil solution's pH will not indicate how much base is needed to change the soil pH. In another experiment, measured amounts of acid and base were added to 10-gram samples of well-mixed soil that had been collected from various locations in a field. The volumes of the samples were equalized by adding water. The results were recorded in Figure 2.

Figure 2.

Which soil from Table 1 most likely has the highest percentage of organic matter?

Alleles are created when a single gene undergoes several distinct mutations. These alleles may have
different dominance relationships with one another; for example, there are three alleles coding for the
human blood groups, the IA, IB, and i alleles. Both the IA and IB alleles are dominant to the i allele, but IA and IB are codominant to each other.

A multiple-allele system has recently been discovered in the determination of hair coloring in a species of wild rat. The rats are found to have one of three colors: brown, red, or white. Let B = the gene for brown
hair; b = the gene for red hair; and w = the gene for white hair. The results from nine experimental crosses

are shown below. The males and females in Crosses 1, 2, and 3 are all homozygous for hair color.

If a large number of brown offspring from Cross 8 are mated with each other, what is the expected percentage of white offspring?

Which of the following reactants should be used to form the product shown below?

One distinguishing factor in a redox titration, as opposed to other titrations, is that it involves:

How will the gravitational force between two objects change if the distance between them is doubled?

The percentage of arthropods in total animal kingdom is:

In the early nineteenth century a large number of communal experiments, both secular and religious, sprang up in the northeastern United States. Perhaps the most famous secular commune was Brook Farm, founded by transcendentalists George Ripley and William H. Channing to promote the pursuit of leisure and culture through the proper application of time and labor. Its members (among the more notable were Nathaniel Hawthorne and Margaret Fuller) pursued field labor by day, art and philosophy by night.
For a time the system worked so well that two afternoons a week were set aside for leisure and Brook Farm began outcompeting local farmers at the produce market. But by nature the Farm's members were
thinkers, not workers; despite their success they remained mainly interested in the theoretical and
philosophical implications of the experiment. Thus, when a devastating fire brought the community considerable financial burdens in its fifth year, the members felt little compunction about closing shop and returning to their comfortable Boston homes.

One of the most notable religious utopias was the Oneida community. Its founder, John Humphrey Noyes, believed that Christ's second coming had already occurred and that everyone alive was favored by Divine grace, which Noyes saw as an imperative to live a better life. Perhaps surprisingly, the Oneidans embraced industry and commerce, achieving success in fruit packing, trap making, and silk thread winding. They owned everything communally, and this principle extended to each other. The Oneidans saw monogamy as a selfish act and asserted that the men and women of the community were united in
one "complex" marriage; sex between any two consenting members was perfectly acceptable. The
Oneidans maintained order solely through "criticism"--anyone acting out of line was made to stand before the other members and hear his or her faults recounted. Oneida remained viable for some thirty years, until the leadership devolved on Noyes' son, an agnostic. The old religious fervor died out, and the dream degenerated into a joint stock company.
Doubtless the most successful communalists were the Shakers, so called for the early propensity to
tremble ecstatically during religious worship. Their guiding light, Mother Ann, espoused four key principles:
Virgin Purity, Christian Communism, Confession, and Separation from the World. Though the Shakers were less adamant on the last point--maintaining social relations and some commerce with heir neighbors--they insisted on the other three, and renounced both personal property and sex. Men and women lived in a single large "Unitary Dwelling" and were considered complete equals, but they occupied separate wings and could speak together only if a third person were present. Despite their religious strictness, Shakers were known as simple, sincere, intelligent people, healthy and long-lived, producers of lovely books and hymns, and of furniture still prized for its quality and durability. In their eyday, six thousand Shakers lived in fifty-eight separate "families" throughout the Northeast. Later their celibacy, combined with their strict discipline, led to a decline in numbers, but even today a small number of elderly Shakers in two communities in Maine and New Hampshire continue to keep the faith.

The passage implies that the end of the Brook Farm experiment was probably brought on by:

The simple harmonic motion of a mass suspended from vertical springs is investigated in two experiments.
The springs used in both experiments have a spring constant k and a natural length L0. The material used to make the springs has a Young's modulus of 2 x 1011 Pa.

In the first experiment a mass m is suspended from a spring. The mass stretches the spring to a new length L, called the equilibrium length.

In the second experiment the mass m is suspended from two identical springs as shown in Figure 2 below.
When the mass m is in equilibrium, each spring is stretched from its natural length by the same amount xe.

In both experiments the masses of the springs are negligible, and the elastic limits of the springs are never exceeded.

In the first experiment, what is the mass of the object hanging from the spring?

Although we know more about so-called Neanderthal men than about any other early population, their exact relation to present-day human beings remains unclear. Long considered sub-human, Neanderthals are now known to have been fully human. They walked erect, used fire, and made a variety of tools. They lived partly in the open and partly in caves. The Neanderthals are even thought to have been the first humans to bury their dead, a practice which has been interpreted as demonstrating the capacity for religious and abstract thought.
The first monograph on Neanderthal anatomy, published by Marcelling Boule in 1913, presented a somewhat misleading picture. Boule took the Neanderthals' lowvaulted cranium and prominent brow ridges, their heavy musculature, and the apparent overdevelopment of certain joints as evidence of a

prehuman physical appearance. In postulating for the Neanderthal such "primitive" characteristics as a stooping, bent-kneed posture, a rolling gait, and a forward-hanging head, Boule was a victim of the rudimentary state of anatomical science. Modern anthropologists recognize the Neanderthal bone structure as that of a creature whose bodily orientation and capacities were very similar to those of present-day human beings. The differences in the size and shape of the limbs, shoulder blades, and other body parts are simply adaptations which were necessary to handle the Neanderthal's far more massive musculature. Current taxonomy considers the Neanderthals to have been fully human and thus designates them not as a separate species, Homo neanderthalensis, but as a subspecies of Homo sapiens: Homo sapiens neanderthalensis. The rise of the Neanderthals occurred over some 100,000 years -- a sufficient period to account for evolution of the specifically Neanderthal characteristics through free interbreeding over a broad geographical range. Fossil evidence suggests that the Neanderthals inhabited a vast area from Europe through the Middle East and into Central Asia from approximately 100,000 years ago until 35,000 years ago. Then, within a brief period of five to ten thousand years, they disappeared. Modern human, not found in Europe prior to about 33,000 years ago, thenceforth became the sole inhabitants of the region. Anthropologists do not believe that the Neanderthals evolved into modern human beings.
Despite the similarities between Neanderthal and modern human anatomy, the differences are great enough that, among a population as broad-ranging as the Neanderthals, such an evolution could not have taken place in a period of only ten thousand years. Furthermore, no fossils of types intermediate between Neanderthals and moderns have been found.
A major alternative hypothesis, advanced by E. Trinkaus and W.W. Howells, is that of localized evolution.
Within a geographically concentrated population, free interbreeding could have produced far more pronounced genetic effects within a shorter time. Thus modern human could have evolved relatively quickly, either from Neanderthals or from some other ancestral type, in isolation from the main Neanderthal population. These humans may have migrated throughout the Neanderthal areas, where they displaced or absorbed the original inhabitants. One hypothesis suggests that these "modern" humans immigrated to Europe from the Middle East. No satisfactory explanation of why modern human beings replaced the Neanderthals has yet been found. Some have speculated that the modern humans wiped out
the Neanderthals in warfare; however, there exists no archeological evidence of a hostile encounter. It has
also been suggested that the Neanderthals failed to adapt to the onset of the last Ice Age; yet their thick
bodies should have been heat-conserving and thus well-adapted to extreme cold. Finally, it is possible that the improved tools and hunting implements of the late Neanderthal period made the powerful Neanderthal physique less of an advantage than it had been previously. At the same time, the Neanderthals' need for a heavy diet to sustain this physique put them at a disadvantage compared to the less massive moderns. If this was the case, then it was improvements in human culture -- including some introduced by the Neanderthals themselves -- that made the Neanderthal obsolete.

It can be inferred from the passage that the rate of evolution is directly related to the:

The James-Lange Theory of Emotion proposes that:

Yeast can be used to covert simple sugars into:

(1) Fluorescent proteins are found in bioluminescent sea creatures, such as jellyfish. (2) In 1969, the green fluorescent protein was discovered and, since then, prolific research has resulted in the discovery and development of many new fluorescent proteins. (3) Fluorescent proteins can be expressed in cells, making them easily visible under a microscope. (4) In fact, the use of fluorescent proteins revolutionized bio-imaging because the inherently natural nature meant that they could be incorporated into living cells with no deadly toxic effects. (5) Numerous other scientific and medical applications also exploit the unique properties of fluorescent proteins, which is why they were the subject of the 2008 Nobel Prize for Chemistry. (6) However, the science behind fluorescent proteins is still not fully understood, and there are many more avenues for exploration.

What is implied by the fourth sentence of the passage?

Due to ever-increasing paranoia about the transmission of hepatitis and AIDS via blood transfusions and the frequent difficulty of procuring matching blood donors for patients, researchers have been working at a feverish pace to produce disease-free and easy-to-use blood substitutes. The difficulty most synthetic blood researches have had is in formulating a substance that combines qualities of sterility, high capacity for carrying oxygen to body tissues, and versatility within the human body. Three major substitute
technologies have been developed to date; each has certain advantages and shortcomings.

"Red blood," the first of the blood substitute technologies, is derived from hemoglobin which has been recycled from old, dead, or worn-out red blood cells and modified so that it can carry oxygen outside the red blood cell. Hemoglobin, a complex protein, is the blood's natural oxygen carrier and is attractive to scientists for use in synthetic blood because of its oxygen-carrying capacity. However, hemoglobin can sometimes constitute a two-fold threat to humans when it is extracted from the red blood cell and introduced to the body in its naked form. First, hemoglobin molecules are rarely sterile and often remain contaminated by viruses to which they were exposed in the cell. Second, naked hemoglobin is extremely dangerous to the kidneys, causing blood flow at these organs to shut down and leading, ultimately, to renal failure. Additional problems arise from the fact that hemoglobin is adapted to operate optimally within the intricate environment of the red blood cell. Stripped of the protection of the cell, the hemoglobin molecule tends to suffer breakdown within several hours. Although modification has produced more durable hemoglobin molecules which do not cause renal failure, undesired side effects continue to plague patients and hinder the development of hemoglobin-based blood substitutes.

Another synthetic blood alternative, "white blood," is dependent on laboratory synthesized chemicals called perfluorocarbons (PFCs). Unlike blood, PFCs are clear oil like liquids, yet they are capable of absorbing quantities of oxygen up to 50% of their volume, enough of an oxygen carrying potential for oxygen-dependent organisms to survive submerged in the liquid for hours by "breathing" it. Although PFCs imitate real blood by effectively absorbing oxygen, scientists are primarily interested in them as constituents of blood substitutes because they are inherently safer to use than hemoglobin-based substitutes. PFCs do not interact with any chemicals in the body and can be manufactured in near-perfect sterility. The primary pitfall of PFCs is in their tendency to form globules in plasma that can block
circulation. Dissolving PFCs in solution can mitigate globulation; however, this procedure also seriously
curtails the PFCs' oxygen capacity.

The final and perhaps most ambitious attempt to form a blood substitute involves the synthesis of a modified version of human hemoglobin by genetically-altered bacteria. Fortunately, this synthetic hemoglobin seems to closely mimic the qualities of sterility, and durability outside the cellular environment, and the oxygen-carrying efficiency of blood. Furthermore, researchers have found that if modified hemoglobin genes are added to bacterial DNA, the bacteria will produce the desired product in copious quantities. This procedure is extremely challenging, however, because it requires the isolation of the human gene for the production of hemoglobin, and the modification of the gene to express a molecule that works without support from a living cell.

While all the above technologies have serious drawbacks and difficulties, work to perfect an ideal blood substitute continues. Scientists hope that in the near future safe synthetic blood transfusions may ease blood shortages and resolve the unavailability of various blood types.

According to the passage, all of the following are reasons for research into the development of synthetic bloods EXCEPT:

As Alice Echols went on to claim, "Nothing seems to conjure up the 1970s quite so effectively as disco.
Even at the time, critics remarked upon disco's neat encapsulation of that decade's zeitgeist. `It must be
clear by now to everyone with an ear or an eye that this era,' wrote journalist Andrew Kopkind in 1979, `is
already the Disco Years, whether it will be called by that name or not.' A former sixties radical, Kopkind was by turns fascinated, bemused, and appalled by the disco epoch, and he likely imagined that in years to come fellow cultural critics would share his interest. But the seventies have not loomed large in our national imagination, except perhaps as comic relief. For many Americans, these were the forgettable years.

That forgettability owes a lot to the 1960s, the outsized decade that dwarfs all others in recent memory.
The sixties will always be remembered for their audacity, whether found in the courage of civil rights protesters who put their bodies on the line or in those doomed but beautiful rock stars who tried breaking through to the other side. By contrast, the seventies seem the decade when nothing, or nothing good, happened ?an era memorable for the country's hapless presidents, declining prestige, bad fashions,
ludicrous music, and such over-the-top narcissism that Tom Wolfe dubbed it the `Me Decade.' Before the
decade was out, this narrative of decline had become routine. `After the poetry of the Beatles comes the
monotonous bass-pedal bombardment of Donna Summer,' huffed one New York Times writer in 1979. It is a measure of the era's persistent bad press that a recent book challenging this view carries the pleading title Something Happened.

As for the sixties, it doesn't matter how much silliness went down, we still invest those times with seismic significance. Take Joe Cocker's performance at Woodstock. His spasmodic thrashing about and his vocals, slurred to the point of incomprehensibility, are something of a joke today. Cringe-inducing though it may be, however, Cocker's performance is never made to stand in for the whole of the sixties. The sixties remain enveloped in the gauzy sentimentalism of what might have been. Yet the iconic image of John Travolta as dance-floor king Tony Manero in white polyester suit, arm thrust to the disco heavens, has come to symbolize the narcissistic imbecility and inconsequentiality of the disco years.

Were it not for the Rubaiyat, I, too, might well regard the seventies as a lamentable and regrettable period in American history. The Rubaiyat was, yes, a disco. It was located in the heart of sixtiesland: Ann Arbor, Michigan, the home of the University of Michigan and legendary incubator of radical activism. At the height of the seventies, the town's annual Hash Bash ?a smoke-in to reform marijuana laws ?was still going strong and so were its two food co-ops-one reform, the other orthodox when it came to selling white foods

(that is, rice, sugar, and flour of the white variety). Ann Arbor also had bookstores galore, including the original, wonderful Borders Bookstore, and any number of hippie-ish restaurants and bars such as the Fleetwood Diner, the Del Rio, and the Blind Pig. Musically, it prided itself on its vintage music (it hosted one of the earliest blues festivals), but at heart it was a rock town besotted with Iggy Pop and the Stooges and Sonic's Rendezvous, a band fronted by Patti Smith's future husband, Fred Smith. Its leading music store, Schoolkids' Records, stocked disco, but never played it. All of this is to say that disco-averse Ann Arbor came close to providing something of a safe haven from glitterball culture.

The Rubaiyat was no red-velvet-rope disco where fashionista doormen determined who was sufficiently fabulous to gain entry. This would never have worked in a town where down jackets and army surplus were hardly an unusual sight. The club did have some pretensions to classiness, but the mismatched, sagging booths and bordello red defeated occasional efforts at upmarket sophistication. What the Rubaiyat did have were better-than-average speakers, a heterogeneous cliente, and a weekend cover of three dollars."

Echols, A. (2011). Hot stuff: Disco and the Remaking of American Culture. New York: W. W. Norton.

The author most closely means which of the following in paragraph 2 by "narrative of decline"?

Fireworks have been used for centuries in celebrations around the world. One of the primary components of these devices, black powder, was developed by the Chinese over a thousand years ago and is still used today as a propellant and explosive. Black powder is composed of potassium nitrate (KNO3), charcoal (primarily C) and sulfur (S8) in a 75:15:10 ratio by weight. It is very stable if kept dry but can easily be ignited by a spark or burning fuse to undergo the following reaction:

Reaction 1
The basic firework is shown in Figure 1. Fireworks rely on a particular kind of combustion in which oxygen is supplied by oxidizing agents included in the pyrotechnic mixture. When ignited, the solid propellant begins to liquefy and vaporize allowing the fuel and oxidizing agents to interact more intimately leading to rapid expansion of gases. Delay fuses time the ignition of the other compartments to occur when the shell is high above ground.

Figure 1

The light generating units of the firework are called stars and are dispersed and ignited by the bursting charge in each compartment. The intense colors of modern fireworks are generated by molecular emitters.
For example, barium chloride emits green light (510?30 nm) and strontium chloride emits vibrant red light (605?50 nm). Many of the molecular emitters are unstable at room temperature and so cannot be placed directly into the firework. Instead, they are synthesized in the flame of the pyrotechnic reaction and exist for a short time before decomposing. The flame temperature must be carefully adjusted so that these emitters
do not decompose too rapidly.

What is the energy of a photon of light emitted by a barium chloride emitter?

Agonistic behavior, or aggression, is exhibited by most of the more than three million species of animals on this planet. Animal behaviorists still disagree on a comprehensive definition of the term, but aggressive behavior can be loosely described as any action that harms an adversary or compels it to retreat.
Aggression may serve many purposes, such as food gathering, establishing territory, and enforcing social hierarchy. In a general Darwinian sense, however, the purpose of aggressive behavior is to increase the individual animal's -- and thus, the species' -- chance of survival.
Aggressive behavior may be directed at animals of other species, or it may be conspecific -- that is, directed at members of an animal's own species. One of the most common examples of conspecific aggression occurs in the establishment and maintenance of social hierarchies. In a hierarchy, social
dominance is usually established according to physical superiority; the classic example is that of a pecking
order among domestic fowl. The dominance hierarchy may be viewed as a means of social control that reduces the incidence of attack within a group. Once established, the hierarchy is rarely threatened by disputes because the inferior animal immediately submits when confronted by a superior. Two basic types of aggressive behavior are common to most species: attack and defensive threat. Each type involves a particular pattern of physiological and behavioral responses, which tends not to vary regardless of the stimulus that provokes it. For example, the pattern of attack behavior in cats involves a series of movements, such as stalking, biting, seizing with the forepaws and scratching with the hind legs, that changes very little regardless of the stimulus -- that is, regardless of who or what the cat is attacking.
The cat's defensive threat response offers another set of closely linked physiological and behavioral patterns. The cardiovascular system begins to pump blood at a faster rate, in preparation for sudden physical activity. The eyes narrow and the ears flatten against the side of the cat's head for protection, and other vulnerable areas of the body such as the stomach and throat are similarly contracted. Growling or hissing noises and erect fur also signal defensive threat. As with the attack response, this pattern of responses is generated with little variation regardless of the nature of the stimulus.
Are these aggressive patterns of attack and defensive threat innate, genetically programmed, or are they learned? The answer seems to be a combination of both. A mouse is helpless at birth, but by its 12th day of life can assume a defensive threat position by backing up on its hind legs. By the time it is one month old, the mouse begins to exhibit the attack response. Nonetheless, copious evidence suggests that
animals learn and practice aggressive behavior; one need look no further than the sight of a kitten playing
with a ball of string. All the elements of attack -- stalking, pouncing, biting and shaking -- are part of the game which prepares the kitten for more serious situations later in life.

The author suggests that the question of whether agonistic behavior is genetically programmed or learned:

The process of depolarization triggers the cardiac cycle. The electronics of the cycle can be monitored by an electrocardiogram (EKG). The cycle is divided into two major phases, both named for events in the ventricle: the period of ventricular contraction and blood ejection, systole, followed by the period of ventricular relaxation and blood filling, diastole.

During the very first part of systole, the ventricles are contracting but all valves in the heart are closed thus no blood can be ejected. Once the rising pressure in the ventricles becomes great enough to open the aortic and pulmonary valves, the ventricular ejection or systole occurs. Blood is forced into the aorta and pulmonary trunk as the contracting ventricular muscle fibers shorten. The volume of blood ejected from a ventricle during systole is termed stroke volume.

During the very first part of diastole, the ventricles begin to relax, and the aortic and pulmonary valves close. No blood is entering or leaving the ventricles since once again all the valves are closed. Once ventricular pressure falls below atrial pressure, the atrioventricular (AV) valves open. Atrial contraction occurs towards the end of diastole, after most of the ventricular filling has taken place. The ventricle receives blood throughout most of diastole, not just when the atrium contracts.

Figure 1: Electronic and pressure changes in the heart and aorta during the cardiac cycle.

The first heart sound represented in Fig. 1 is probably made when:

The rich analyses of Fernand Braudel and his fellow Annales historians have made significant contributions to historical theory and research. In a departure from traditional historical approaches, the Annales historians, assume (as do Marxists) that history cannot be limited to a simple recounting of conscious human actions, but must be understood in the context of forces and material conditions that underlie human behavior. Braudel was the first Annales historian to gain widespread support of the idea that history should synthesize data from various social sciences, especially economics, in order to provide a broader view of human societies over time (although Febvre and Bloch, founders of the Annales school, had originated this approach).
Braudel conceived of history as the dynamic interaction of three temporalities. The first of these, the evenementielle, involved short-lived dramatic "events," such as battles, revolutions and the actions of great men, which had preoccupied traditional historians like Carlyle. Conjonctures was Braudel's term for larger cyclical processes that might last up to half a century. The longue duree, a historical wave of great length, was for Braudel the most fascinating of the three temporalities. Here he focused on those aspects of everyday life that might remain relatively unchanged for centuries. What people ate, what they wore, their means and routes of travel -- for Braudel these things create "structures" which define the limits of potential social change for hundreds of years at a time.
Braudel's concept of the longue duree extended the perspective of historical space as well as time. Until the Annales school, historians had taken the juridical political unit the nation-state, duchy, or whatever as their starting point. Yet, when such enormous timespans are considered, geographical features may well have more significance for human populations than national borders. In his doctoral thesis, a seminal work on the Mediterranean during the reign of Philip II, Braudel treated the geohistory of the entire region as a "structure" that had exerted myriad influences on human lifeways since the first settlements on the shores of the Mediterranean Sea. And so the reader is given such arcane information as the list of products that came to Spanish shores from North Africa, the seasonal routes followed by Mediterranean sheep and their shepherds, and the cities where the best ship timber could be bought. Braudel has been faulted for the imprecision of his approach. With his Rabelaisian delight in concrete detail, Braudel vastly extended the
realm of relevant phenomena; but this very achievement made it difficult to delimit the boundaries of
observation, a task necessary to beginning any social investigation. Further, Braudel and other Annales historians minimize the differences among the social sciences. Nevertheless, the many similarly-designed studies aimed at both professional and popular audiences indicate that Braudel asked significant questions which traditional historians had overlooked.

The passage suggests that, compared with traditional historians, Annales historians are:

The anthropomorphic bias of those who would relegate marsupials to an inferior evolutionary status is most apparent in their recourse to data on brain structure and behavior. Unlike humans and other placentals, marsupials lack the corpus callosum, which facilitates inter-hemisphere transfer of data acquired through the senses. Yet it cannot be inferred that marsupials are thus deprived of such function.
Didelphis Virginiana, one of the opossums, makes use of the anterior commissure, an adaptation that is also found in reptiles and monotremes. Diprodontons, including kangaroos and koalas, supplement the anterior commissure with the fasciculus aberrans. While the modes of neocortical interconnection may be diverse, the work of Johnson, Heath and Jones points to the conclusion that, functionally speaking the cortices and neocortices of both groups of mammals exhibit parallel connections. Parker also notes "a similar range of brain size to body weight ratios and of neocortical expansion".
Another stigma borne by marsupials is the consensus that they are less intelligent than placentals. Yet Williams argues that, all else being equal, natural selection will favor instinctive over learned behavior as being more biologically efficient and that it is the accidental death of the young that is the prime selective
pressure for the evolution of intelligence. Seen in this light, marsupials have a competitive edge; their
gestation period is brief and the young remain in the pouch for an extended period exposed only to those dangers which also affect the mother. There they are directly exposed to the mother's food supply and can observe her behavior at leisure. Placentals, on the other hand, not only have a longer gestation period but, once their young are born, must often leave while foraging. Such absences increase the risk of mortality and decrease the opportunity to learn. Thus, among placentals, selection would favor the apparent intelligence in the young and protective behavior in the mother.
Marsupials are not known to exhibit maternal protective behavior. In fact, Serventy has reported that frightened female kangaroos will drop their pouch-young as they flee, drawing a predator's attention to the less able offspring while the adult escapes. This behavior, whether purposeful or accidental, instantaneously relieves the female marsupial of the mechanical difficulties of pregnancy with which her placental counterpart would be burdened, while marsupials can replace any lost young quickly. Thus, in the absence of any need for close maternal supervision, sacrificing their offspring in this manner may well have been favored in selection. Pointing to the absence of the "virtue" of maternal protectiveness in marsupials is an instance of how mistaken are those theorists who see similarities with humans as marks of evolutionary sophistication.

The author's primary purpose in this passage is to:

The atomic size of an atom is:

The reaction below is NOT spontaneous at any temperature.
2ICl(g) I2(g) + Cl2(g)

Which of the following is true?

Oversecretion of gastric HCl can be treated by severing the vagus nerve in a procedure called a vagotomy which reduces parasympathetic activity.

Which of the following effects is LEAST likely to be caused by a vagotomy?

Aski jump is an inclined track from which a ski jumper takes off through the air. After traveling down the track, the skier takes off from a ramp at the bottom of the track. The skier lands farther down on the slope.

Figure 1 shows a ski jump, in which the ramp at the lower end of the track makes an angle of 30° to the horizontal. The track is inclined at an angle of to the horizontal and the slope is inclined at an angle of 45° to the horizontal. A ski jumper is stationary at the top of the track. Once the skier pushes off, she accelerates down the track, and then takes off from the ramp. The vertical height difference between the top of the track and its lowest point is 50 m, and the vertical height difference between the top of the ramp and its lowest point is 10 m.

Figure 1

The distance traveled by the skier between leaving the ski jump ramp and making contact with the slope is called the jump distance. In some cases, in order to increase the jump distance a skier will jump slightly upon leaving the ramp, thereby increasing the vertical velocity. Unless otherwise stated, assume that friction between the skis and the slope is negligible, and ignore the effects of air resistance.

How would the work done by gravity on the skier when she skis down the track compare with the work done by gravity on the skier if she fell the same vertical height?

Aerobic respiration is the major process used by oxygen-requiring organisms to generate energy. During respiration, glucose is metabolized to generate chemical energy in the form of ATP:

The biochemical machinery necessary for cellular respiration is found in the mitochondria, small organelles scattered throughout the cytoplasm of most eukaryotic cells. The number of mitochondria per cell varies by tissue type and cell function.

Mitochondria are unusual in that they have their own genetic systems that are entirely separate from the cell's genetic material. However, mitochondrial replication is still dependent upon the cell's nuclear DNA to encode essential proteins required for replication. Despite this fact, mitochondria seem to replicate randomly, out of phase with both the cell cycle and other mitochondria.

The nature of the mitochondrial genome and protein synthesizing machinery has led many researchers to postulate that mitochondria may have arisen as the result of the ingestion of a bacterium by a primitive cell millions of years ago. It is postulated that the two may have entered into a symbiotic relationship and
eventually became dependent on each another; the cell sustained the bacterium, while the bacterium
provided energy for the cell. Gradually, the two evolved into the present-day eukaryotic cell, with the mitochondrion retaining some of its own DNA. This is known as the endosymbiotic hypothesis. Because mitochondrial DNA is inherited in a non-Mendelian fashion (mitochondria are inherited from the maternal parent, who supplies most of the cytoplasm to the fertilized egg), it has been used to look at evolutionary
relationships among different organisms.

Scientists have demonstrated that human mitochondrial DNA mutates at a fairly slow rate. Because mitochondria play such an important role in the cell, these mutations are most likely to be:

Although we know more about so-called Neanderthal men than about any other early population, their exact relation to present-day human beings remains unclear. Long considered sub-human, Neanderthals are now known to have been fully human. They walked erect, used fire, and made a variety of tools. They lived partly in the open and partly in caves. The Neanderthals are even thought to have been the first humans to bury their dead, a practice which has been interpreted as demonstrating the capacity for religious and abstract thought.
The first monograph on Neanderthal anatomy, published by Marcelling Boule in 1913, presented a somewhat misleading picture. Boule took the Neanderthals' lowvaulted cranium and prominent brow

ridges, their heavy musculature, and the apparent overdevelopment of certain joints as evidence of a prehuman physical appearance. In postulating for the Neanderthal such "primitive" characteristics as a stooping, bent-kneed posture, a rolling gait, and a forward-hanging head, Boule was a victim of the rudimentary state of anatomical science. Modern anthropologists recognize the Neanderthal bone structure as that of a creature whose bodily orientation and capacities were very similar to those of present-day human beings. The differences in the size and shape of the limbs, shoulder blades, and other body parts are simply adaptations which were necessary to handle the Neanderthal's far more massive musculature. Current taxonomy considers the Neanderthals to have been fully human and thus designates them not as a separate species, Homo neanderthalensis, but as a subspecies of Homo sapiens: Homo sapiens neanderthalensis. The rise of the Neanderthals occurred over some 100,000 years -- a sufficient period to account for evolution of the specifically Neanderthal characteristics through free interbreeding over a broad geographical range. Fossil evidence suggests that the Neanderthals inhabited a vast area from Europe through the Middle East and into Central Asia from approximately 100,000 years ago until 35,000 years ago. Then, within a brief period of five to ten thousand years, they disappeared. Modern human, not found in Europe prior to about 33,000 years ago, thenceforth became the sole inhabitants of the region. Anthropologists do not believe that the Neanderthals evolved into modern human beings.
Despite the similarities between Neanderthal and modern human anatomy, the differences are great enough that, among a population as broad-ranging as the Neanderthals, such an evolution could not have taken place in a period of only ten thousand years. Furthermore, no fossils of types intermediate between Neanderthals and moderns have been found.
A major alternative hypothesis, advanced by E. Trinkaus and W.W. Howells, is that of localized evolution.
Within a geographically concentrated population, free interbreeding could have produced far more pronounced genetic effects within a shorter time. Thus modern human could have evolved relatively quickly, either from Neanderthals or from some other ancestral type, in isolation from the main Neanderthal population. These humans may have migrated throughout the Neanderthal areas, where they displaced or absorbed the original inhabitants. One hypothesis suggests that these "modern" humans immigrated to Europe from the Middle East. No satisfactory explanation of why modern human beings replaced the Neanderthals has yet been found. Some have speculated that the modern humans wiped out
the Neanderthals in warfare; however, there exists no archeological evidence of a hostile encounter. It has
also been suggested that the Neanderthals failed to adapt to the onset of the last Ice Age; yet their thick
bodies should have been heat-conserving and thus well-adapted to extreme cold. Finally, it is possible that the improved tools and hunting implements of the late Neanderthal period made the powerful Neanderthal physique less of an advantage than it had been previously. At the same time, the Neanderthals' need for a heavy diet to sustain this physique put them at a disadvantage compared to the less massive moderns. If this was the case, then it was improvements in human culture -- including some introduced by the Neanderthals themselves -- that made the Neanderthal obsolete.

All of the following are hypotheses about the disappearance of the Neanderthals EXCEPT:

Sugars are carbohydrates, that is, molecules usually with the empirical formula C(H2O), and structural formulas made up of polyhydroxy aldehydes or ketones. Because of their polyfunctional nature, sugars can undergo a wide variety of transformations upon treatment with acids, bases, or heat, and upon reaction with other simple reagents and enzymes. While many sugars occur in nature and are thus readily available, the synthesis and modification of simple sugars is a necessary step in studies of enzymatic processes.
Higher sugars can be synthesized from the simple carbohydrate D-glyceraldehyde with the following procedure: D-glyceraldehyde (Compound A) is reacted with HCN to produce a cyanohydrin (Compound B).
Compound B is then treated with hydrogen gas and a modified palladium catalyst (similar to the Lindlar reagent) to give Compound C. Compound C is hydrolyzed to give the higher sugars in Mixture D. This reaction is summarized in Figure 1. Mixture D contains two compounds, which can be separated by crystallization. Two doublets near 9.5 (, ppm) are observed in the 1H NMR spectrum of mixture D, with each doublet corresponding to one of the two products present in the mixture. IR spectroscopy shows broad absorptions for both products around 3300 cm?.

The hydroxyl groups of carbohydrates can also participate in reactions. For example, D-glyceraldehyde can react with chloromethane under basic conditions to yield a completely methylated product. This SN2 reaction is shown in Figure 2.

Figure 2 Methylation of D-glyceraldehyde

The two sugars in Mixture D are:

A hovercraft is a versatile vehicle capable of traveling over land, water, or any other essentially flat surface.
The hovercraft consists of a body or hull onto which a rotor (lift fan) is mounted. The lift fan provides the vertical lift by propelling air into an area beneath the hovercraft called the skirt. The pocket of air in the skirt supports the moving hovercraft and reduces the friction between the vehicle and the ground to almost zero. As such, there is no contact between the hovercraft and the ground.

A second fan, which generates a horizontal thrust, propels the hovercraft forward. Rudders which direct the airflow from this second fan are used by the pilot to control the movement of the hovercraft. The horizontal movement of the

hovercraft is opposed by air resistance which generates aerodynamic drag.

A 600 kg hovercraft traveling across a frozen lake accelerates from rest to a speed of 60 kilometers per hour in 4 seconds.

What is the average force produced by the thrust fan?

When a radio station is broadcasting a musical program, the antenna of its transmitter:

The pigment in blue-green algae that distinguishes them from other algae is:

Synthetic dyes constitute a commercially significant area of organic chemistry. The color producing properties of these compounds are the result of highly delocalized electron systems giving rise to electronic transitions whose absorptions occur in the visible region. Most commercially useful dyes can be classified as one of three types -- anthraquinones, azo dyes, or triarylmethyl salts. Examples of each type are illustrated in Figure 1.

Figure 1

In order for a dye to be useful in the fabric industry, it must have sufficient affinity for the polymeric fibers of
which the material is composed; the dye must not only impart a color to the fabric, but must also do so in a
relatively permanent manner (color fastness). Proper design of synthetic polymers requires the placement of acidic or basic side chains along the polymer backbone such that binding sites are available for dying.
Similarly, dyes must be produced not only with the appropriate color-producing structure, but also with an affinity for the fabric in question. The structural units of several common synthetic fibers are shown in Figure 2.

Figure 2

Dacron belongs to which of the following general classifications?

Sugars are carbohydrates, that is, molecules usually with the empirical formula C(H2O), and structural formulas made up of polyhydroxy aldehydes or ketones. Because of their polyfunctional nature, sugars can undergo a wide variety of transformations upon treatment with acids, bases, or heat, and upon reaction with other simple reagents and enzymes. While many sugars occur in nature and are thus readily available, the synthesis and modification of simple sugars is a necessary step in studies of enzymatic processes.
Higher sugars can be synthesized from the simple carbohydrate D-glyceraldehyde with the following procedure: D-glyceraldehyde (Compound A) is reacted with HCN to produce a cyanohydrin (Compound B).
Compound B is then treated with hydrogen gas and a modified palladium catalyst (similar to the Lindlar reagent) to give Compound C. Compound C is hydrolyzed to give the higher sugars in Mixture D. This reaction is summarized in Figure 1. Mixture D contains two compounds, which can be separated by crystallization. Two doublets near 9.5 (, ppm) are observed in the 1H NMR spectrum of mixture D, with each doublet corresponding to one of the two products present in the mixture. IR spectroscopy shows broad absorptions for both products around 3300 cm?.

The hydroxyl groups of carbohydrates can also participate in reactions. For example, D-glyceraldehyde can react with chloromethane under basic conditions to yield a completely methylated product. This SN2 reaction is shown in Figure 2.

Figure 2 Methylation of D-glyceraldehyde

The modified palladium catalyst is used instead of platinum to:

When preparing for the MCAT exam, a student begins studying electrochemical cells. He learns the basic information needed by actively relating it to previous information he has learned about redox reactions. He then builds from that knowledge to learn the advanced concepts needed. The student's process is best characterized as:

A student was given a sample of an unknown liquid and asked to determine as much as possible about its structure. He was told that the compound contained only carbon, hydrogen, and oxygen, and had only one type of functional group. The student found its boiling point to be 206°C. Using mass spectroscopy, he determined its molecular weight to be 138 g/mol. Finally, he took the infrared spectrum of the compound, which is shown below.

From this spectrum, the student quickly reached a conclusion about the functional group. He then turned his attention to the fingerprint region of the compound, which generally has a complicated pattern of peaks that are determined by the structure of the hydrocarbon portion of a molecule. The student decided that the large peak at 750 cm-1 must indicate that this was a disubstituted aromatic compound.

Assuming that all of the student's deductions were correct, which of the following could be the structure of the unknown compound?

If volume of a given mass of a gas is doubled without changing its temperature, the density of the gas:

Breast milk is proven to be the best form of nutrition for infants and is recommended for at least 1 year after birth. Unfortunately, a recent survey of breastfeeding mothers revealed that only 20% continue breastfeeding or to provide breast milk through pumping after 4 months, after which they switch to formula.
When asked about reasons for stopping breastfeeding, the top three reasons were: going back to work, lack of support, and difficulties pumping. A socioeconomic study of the mothers revealed that women who choose to breastfeed for longest tend to have a higher level of education and come from more affluent backgrounds. Conversely, those mothers who breastfeed for the least amount of time tend to belong to minority groups and are from poorer backgrounds. It has been proposed that cultural differences also have a significant impact on the duration of breastfeeding.

According to the passage, if the Department of Health specifically wants to increase the minimum length of breastfeeding time, on whom should they focus their campaign?

Bebop lives! cries the newest generation of jazz players. During the 1980s, musicians like Wynton Marsalis revived public interest in bebop, the speedy, angular music that first bubbled up out of Harlem in the early 1940s, changing the face of jazz. That Marsalis and others thought of themselves as celebrating and preserving a noble tradition is, in one sense, inevitable. After the excesses of experimental or "free" jazz in the 1960s and the electronic jazz-rock "fusion" of the 70s, it is hardly surprising that people should hearken back to a time when jazz was "purer," perhaps even at the apex of its development. But the recent enthusiasm for bebop is also ironic in light of the music's initial public reception.

In its infancy, during the first two decades of the 20th century, jazz was played by small groups of musicians improvising variations on blues tunes and popular songs. Most of the musicians were unable to read music, and their improvisations were fairly rudimentary. Nevertheless, jazz attained international recognition in the 1920s. Two of the people most responsible for its rise in popularity were Louis Armstrong, the first great jazz soloist, and Fletcher Henderson, leader of the first great jazz band.
Armstrong, with his buoyant personality and virtuosic technical skills, greatly expanded the creative range and importance of the soloist in jazz. Henderson, a pianist with extensive training in music theory, foresaw the orchestral possibilities of jazz played by a larger band. He wrote out arrangements of songs for his band members that preserved the spirit of jazz, while at the same time giving soloists a more structured musical background upon which to shape their solo improvisations. In the 1930s, jazz moved further into the mainstream with the advent of the Swing Era. Big bands in the Henderson mold, led by musicians like Benny Goodman, Count Basie and Duke Ellington, achieved unprecedented popularity with jazz-oriented
"swing" music that was eminently danceable.

Against this musical backdrop, bebop arrived on the scene. Like other modernist movements in art and literature, bebop music represented a departure from tradition in both form and content, and was met with initial hostility. Bebop tempos were unusually fast, with the soloist often playing at double time to the backing musicians. The rhythms were tricky and complex, the melodies intricate and frequently dissonant, involving chord changes and notes not previously heard in jazz. Before bebop, jazz players had improvised on popular songs such as those produced by Tin-Pan Alley, but bebop tunes were often originals with which jazz audiences were unfamiliar.

Played mainly by small combos rather than big bands, bebop was not danceable; it demanded intellectual
concentration. Soon, jazz began to lose its hold on the popular audience, which found the new music disconcerting. Compounding public alienation was the fact that bebop seemed to have arrived on the scene in a completely mature state of development, without that early phase of experimentation that typifies so many movements in the course of Western music. This was as much the result of an accident of history as anything else. The early development of bebop occurred during a three-year ban on recording in this country made necessary by the petrol and vinyl shortages of World War II. By the time the ban was lifted, and the first bebop records were made, the new music seemed to have sprung fully-formed like Athena from the forehead of Zeus. And though a small core of enthusiasts would continue to worship bebop pioneers like Charlie Parker and Dizzy Gillespie, many bebop musicians were never able to gain acceptance with any audience and went on to lead lives of obscurity and deprivation.

Based on the information in the passage comparing bebop to other movements in the history of Western music, it is reasonable to conclude that:

I. most movements in music history passed through a stage of experimentation before reaching mature
expression.
II. World War II prevented bebop from reaching a more appreciative audience.
III. bebop did not go through a developmental stage before reaching mature expression.

Today's new urban Asia is just as sophisticated and in many ways more exciting than Western cities.
Urban Asian consumers are knowledgeable, modern, and keen to embrace the global lifestyle. Young, urban Asians have grown up accustomed to many things that originated in the West. They have, for example, completely embraced pizza, some even claiming that it is a part of their heritage. The story is told about a young Singaporean boy who was taken by his father to Rome. "Hey, look, Dad," the little boy exclaimed, "they have pizza here too!" On sampling the product, the boy decided that it was not as good as the original back home. Nury Vitachi, who writes for the South China Post and the Far Eastern Economic Review, describes the Asian middle-class phenomenon: "Executives in Asia have become rich at warp speed by taking full control of their own lives. They invest a great deal of time in their work, they use strategy to scramble up the corporate ladder, and they demand payment in cash -- so they can make their money work as hard as they do." Signs of affluence are everywhere, but don't get carried away.
Traveling around Asia, no matter how rich the Asians become, signs of their frugal nature are still apparent. And they are very cost-conscious. Shopkeepers in many Asian cities, most notably in Hong Kong, demand payments for discounted merchandise in cash instead of plastic, and many Asians are accustomed to that. Most people save the increases in their income, and many prefer to put it into fixed or other income-generating assets. Stock, land, and property are their favorites.
Many affluent Asians still regard financial security as the most important form of security, and they are confident that Asia is the place to be to achieve that. While many have begun to savor the good life, they are not letting go of their top priority of education for their children. Education is looked upon as the most

important contributing factor to success in life. And in many of Asia's competitive urban centers, there is a rush to acquire a second degree and other forms of professional qualification to ensure personal competitiveness in the workplace. There are extraordinary opportunities in Asia for education and training programs from language to software programming. Despite the rise in their assertiveness, Asians still look to the United States and not so much to Europe for ideas and trends. In general, except for those in Hong Kong and Japan, they are not particularly concerned with being fashionable. For today's Asia, Japan and Hong Kong are the sources of Asian fashion ideas, but as Asia becomes more affluent, there is a great opportunity to develop an indigenous fashion industry. For example, a huge market potential exists in introducing new materials and simplified but fashionable designs for countries in tropical Asia with a hot humid climate throughout the year. The population density and lack of space in urban areas has prohibited Asians from exercising frequently and few indulge in outdoor activities. This is changing. Most Asians consider themselves in good health. Compared with Americans, few are overweight -- largely as a result of their Asian diet. But now health clubs are becoming popular among younger Asians. Potential for indoor exercise equipment holds great promise. It is also important to dress for the gym, and younger Asians are serious about looking good, complete with makeup, sunglasses, designer exercise shoes and outfits, and a gym bag.
In trying to hit Asia's moving targets, regardless of what you are selling, it is a good idea to stick with market density -- not country by country, but, mostly, city by city. Asian markets can be a marketer's dream in that their densities are among the highest in the world. Java, Indonesia's main island, has 115 million people. On Nanjing Road, Shanghai's busiest street, businesses are open twelve hours a day almost every day of the year. More than 1.5 million people visit the shops there and spend more than $50 million every day.
Someone said that you can only become rich if you sell to the rich. I would add that you can become rich faster if you sell to the new rich. For investors in the West, watch for Western companies that are preparing a big push in Asia. The world has not yet seen anything like it before, and you can reap handsome dividends if you back those stocks that are going eastward.

It can be inferred from the passage that:

Several models have been developed for relating changes in dissociation constants to changes in the

tertiary and quaternary structures of oligomeric proteins. One model suggests that the protein's subunits can exist in either of two distinct conformations, R and T. At equilibrium, there are few R conformation molecules: 10 000 T to 1 R and it is an important feature of the enzyme that this ratio does not change.
The substrate is assumed to bind more tightly to the R form than to the T form, which means that binding of the substrate favors the transition from the T conformation to R.

The conformational transitions of the individual subunits are assumed to be tightly linked, so that if one subunit flips from T to R the others must do the same. The binding of the first molecule of substrate thus promotes the binding of the second and if substrate is added continuously, all of the enzyme will be in the R form and act on the substrate. Because the concerted transition of all of the subunits from T to R or back, preserves the overall symmetry of the protein, this model is called the symmetry model. The model further predicts that allosteric activating enzymes make the R conformation even more reactive with the substrate while allosteric inhibitors react with the T conformation so that most of the enzyme is held back in the T shape.

Experiment Evaluating Non-Symmetry Model Enzymes

Experiments were performed with enzyme conformers that did not obey the symmetry model. The data is summarized in Figure 1.

Figure 1: Equilibrium distribution of two conformers at different temperatures given the free energy of their interconversion. (modified from Mr.Holmium).

The substrate binds more tightly to R because:

Band theory explains the conductivity of certain solids by stating that the atomic orbitals of the individual atoms in the solid merge to produce a series of atomic orbitals comprising the entire solid. The closely-spaced energy levels of the orbitals form bands. The band corresponding to the outermost occupied subshell of the original atoms is called the valence band. If partially full, as in metals, it serves as a conduction band through which electrons can move freely. If the valence band is full, then electrons must be raised to a higher band for conduction to occur. The greater the band gap between the separate valence and conduction bands, the poorer the material's conductivity. Figure 1 shows the valence and conduction bands of a semiconductor, which is intermediate in conductivity between conductors and insulators.

Figure 1

When silicon, a semiconductor with tetrahedral covalent bonds, is heated, a few electrons escape into the conduction band. Doping the silicon with a few phosphorus atoms provides unbonded electrons that escape more easily, increasing conductivity. Doping with boron produces holes in the bonding structure, which may be filled by movement of nearby electrons within the lattice. When a semiconductor in an electric circuit has excess electrons on one side and holes on the other, electron flow occurs more easily from the side with excess electrons to the side with holes than in the reverse direction.

Figure 2

The energy of the band gap for pure silicon is about 1.1 electron volts. If a 1.5-volt electrical potential is connected across a sample of silicon:

In 1972, Georges Ungar reported the discovery of a peptide that appeared to transfer learning. Ungar's claim was based on experiments in which rats placed in a chamber with specially designed dark and light regions were trained to avoid the dark regions of the chamber. Following their training, the rats were killed and brain extracts were prepared. These brain extracts were injected into naive rats which were then observed to acquire the fear of darkness without training. Two hypotheses were proposed to explain these remarkable results:

Hypothesis 1
Ungar concluded that the extracts contained some chemical that transmitted the learned fear of darkness to the naive rats. A fifteen amino-acid polypeptide was isolated from the brain extracts and sequenced.
Ungar claimed that this peptide, called scotophobin, was a chemical transmitter of learning. The peptide had the primary structure shown below: C-ser-asp-asn-arg-gln-gln-gly-lys-ser-ala-arg-gln-glygly-tyr-N scotophobin

Hypothesis 2
Other researchers, who tested scotophobin but could not reproduce Ungar's results, argued that scotophobin did not transfer the learned fear of darkness. Instead, they suggested that scotophobin, which is structurally similar to ACTH and vasopressin, acted to increase stress in the rats. Since stress increases sympathetic nervous activity, rats injected with scotophobin would become hyperactive and tend to spend less time in the dark regions of the experimental chamber. They argued that such stress responses in the rats could be misinterpreted as a fear of darkness. Ungar's claim was further weakened by chemical analysis in which both the scotophobin extracts which Ungar had injected into the naive rats and a sample of synthesized scotophobin peptide were subjected to SDS polyacrylamide gel electrophoresis, as shown in Figure 1.

Figure 1

In a follow-up experiment, researchers administered scotophobin to rats in order to examine its physiological effects.

Which of the following observations of physiological effects in the rat would provide the best support for Hypothesis 2?

The body compensates for increased environmental temperature by:

Artificial kidneys have been used for almost 50 years to treat patients with different forms of renal failure.
The artificial kidney (dialysis machine) removes unwanted substances from the blood by diffusion. A patient's blood is passed through channels bounded by a porous, semi-permeable membrane that allows the free diffusion in both directions of all plasma constituents except the plasma proteins. Erythrocytes and other cellular components of blood cannot pass through the membrane. The other side of the membrane is exposed to the dialyzing fluid which carries away the unwanted materials.
If the concentration of a material in the blood is greater than in the dialyzing fluid, there will be a net flow of the material from the plasma to the dialyzing fluid. If the concentration of a material in the blood is less than in the dialyzing fluid, there will be a net flow of the material from the dialyzing fluid into the blood. The composition of normal plasma, plasma in an individual suffering renal failure, and dialyzing fluid are shown in Table 1.

Table 1

Dialysis replaces some functions of the kidneys and attempts to correct the effects of renal failure. For example, patients with renal failure develop acidosis due to a buildup of metabolically produced acids in the circulation. Without dialysis, the pH of the blood will drop and coma may occur. Dialyzing fluid contains a relatively high concentration of bicarbonate which diffuses into the circulation and neutralizes the acid.

The semi-permeable membrane of the dialysis machine functions in a manner most analogous to which part of the kidney?

...Squeaking sand produces sounds with very high frequencies -- between 500 and 2,500 hertz, lasting less than a quarter of a second. The peals are musically pure, often containing four or five harmonic overtones. Booming sand makes louder, low-frequency sounds of 50 to 300 hertz, which may last as long as 15 minutes in larger dunes (although typically they last for seconds or less). In addition, they are rather noisy, containing a multitude of nearby frequencies. Booms have never been observed to contain more than one harmonic of the fundamental tone.
These dramatic differences once led to a consensus that although both types of sand produce acoustic emissions, the ways in which they do so must be substantially different.... In the late 1970s, however, Peter K. Haff, then at the California Institute of Technology, produced squeaks in booming sand, suggesting a closer connection between the two.
Both kinds of sand must be displaced to make sounds. Walking on some sand, for example, forces the sand underfoot to move down and out, producing squeaks. In the case of booming sand, displacement occurs during avalanches. It is within the avalanche that sound begins and where the answers must be hiding.
Before an avalanche can occur, winds must build a dune up to a certain angle, usually about 35 degrees for dry desert sand. Once an angle is achieved, the sand on the leeward side of the dune begins to slump.
Intact layers of sand slip over the layers below, like a sheared deck of cards. At the same time, the individual grains in the upper layers tumble over the grains underneath, momentarily falling into the spaces between them and bouncing out again to continue their downward journey. Their concerted up-and-down motion is believed to be the secret source of sound. Fully developed avalanches, in which sliding plates of sand remain intact for most of their motion, have the greatest acoustic output. In some places, where large amounts of sand are involved, booming can be heard up to 10 kilometers away.
Because it is caused by large volumes of shearing sand, the roaring is also loud. In fact, sounds made by booming sand can be nearly deafening, and the vibrations causing them can be so intense that standing in their midst is nearly impossible.
A good place to start in exploring the vibrational properties of sand is with the grains themselves. The mean diameter of most sand grains, whether acoustically active or not, is about 300 microns. Usually the grains in a booming dune are very similar in size, especially near the leeward crest, where the sound most
often originates; such uniformity allows for more efficient shearing. Otherwise, the smaller grains impede
the smooth motion of the larger ones. Similar sizes do not alone allow sand to boom. On the contrary, the booming sands of Korizo and Gelf Kebib, also in Libya, feature an uncharacteristically broad range of particle sizes. Moreover, silent dune sand often contains grains somewhat similar to nearby booming sand.
Grains of booming sand also tend to have uncommonly smooth surfaces, with protrusions on the scale of
mere microns. Booming dunes are often found at the downwind end of large sand sources; having
bounced and rolled across the desert for long distances, the sand grains in these dunes are usually highly polished. Over time a grain can also be polished by repeated shifts within a moving dune. And squeaking sand as well tends to be exceptionally smooth.... ...Another important factor is humidity, because moisture can modify the friction between grains or cause sand to clump together, thus precluding shearing. Sounds occur in those parts of the dune that dry the fastest. Precipitation may be rare in the desert, but dunes retain water with remarkable efficiency. Sand near the surface dries quickly, however, and sand around a dune's crest tends to dry the fastest.

Which of the following discoveries would give the most support to the hypothesis that squeaking sand and booming sand differ only in the mechanism by which the sounds are produced?

X-rays are produced by a device which beams electrons with an energy between 103 and 106 eV at a metal plate. The electrons interact with the metal plate and are stopped by it. Much of the energy of the incoming electrons is released in the form of X-rays, which are highenergy photons of electromagnetic radiation. An example of such a device is shown below. Electrons are accelerated from the cathode towards the anode by an electric field.

There are two mechanisms by which the X-rays are produced within the metal. The first mechanism is called bremsstrahlung, which is German for "breaking radiation." X-rays are emitted by the electrons as they are brought to rest by interactions with the positive nuclei of the anode.

The second mechanism occurs when an incoming electron knocks an inner electron out of one of the metal atoms of the anode. This electron is replaced by an electron from a higher energy level of the atom, and a photon making up the energy difference is emitted.
X-rays are absorbed by a material when they pass through it. The amount of X-rays absorbed increases with the density of the material. In addition, lower energy X-rays are more likely to be absorbed than higher
energy X-rays. (Note: 1 eV = 1.6 x 1019J; Planck's constant h = 4.1 x 10-15 eV-s; speed of light c = 3 x
108 m/s.)

Which of the following graphs best represents the relationship between the amount of X-rays absorbed per unit length of material and the energy of the X-rays, for lead, bone, and air?

The automobile airbag was designed to inflate upon impact and decrease the risk of injury to drivers and passengers. Among the challenges to its development was the need to find a reliable inflation mechanism that was sufficiently rapid, controllable, and nontoxic. Prototypes employing compressed gases failed to meet these criteria. Researchers thus turned their attention to chemical alternatives.

The ideal inflatant requires a chemical reaction in which the reactants are stable and relatively dense in the condensed phase while the products are mostly or completely gaseous at ambient temperature and pressure. Additionally, the ideal chemical reaction would require a low activation energy and have a high kinetic rate constant, without the large exothermicity characteristic of most such reactions. Traditional explosives such as nitroglycerin, C3H5N3O9(l), were rejected almost immediately because of the extremely exothermic nature of their conversion. Benign solids such as calcium carbonate, CaCO3 , were similarly rejected, because of their large activation requirements. The desired attributes were finally found in sodium azide, NaN3, a stable, dense, ionic solid which rapidly decomposes into elemental sodium and nitrogen gas when ignited by an electrical impulse.

Reaction 1

The gas generating mixture includes excess KNO3 which reacts with the sodium metal from Reaction 1 to produce additional N2 and potassium and sodium oxides (Reactions 2 and 3). These oxides react with SiO2 to produce a non-toxic and stable alkaline silica (glass).

Reaction 2

Reaction 3

Potassium chlorate, KClO3(s), decomposes when heated, yet it is unsuitable as an airbag inflatant. All of the following characteristics of KClO3 make it a poor candidate for an air bag inflatant EXCEPT:

If tension in the string remains constant but the diameter of the sitting is doubled, what will be the effect on speed of transverse waves in the string?

What is the structure associate with BF3 molecule?

The simple harmonic motion of a mass suspended from vertical springs is investigated in two experiments.
The springs used in both experiments have a spring constant k and a natural length L0. The material used to make the springs has a Young's modulus of 2 x 1011 Pa.

In the first experiment a mass m is suspended from a spring. The mass stretches the spring to a new length L, called the equilibrium length.

In the second experiment the mass m is suspended from two identical springs as shown in Figure 2 below.
When the mass m is in equilibrium, each spring is stretched from its natural length by the same amount xe.

In both experiments the masses of the springs are negligible, and the elastic limits of the springs are never exceeded.

The two springs in Experiment 2 are replaced by a single spring having a spring constant k' such that the equilibrium length xe does not change.

What is the ratio of k' to k?

Which of the following phases are common to cells undergoing meiosis and mitosis?

I. G0 phase
II. G2 phase
III. S phase

Which of the following best illustrates the contracted state of the sarcomere shown below?

Electromagnetic radiation from space constantly bombards the earth. Most wavelengths are absorbed by
the atmosphere; however, there are two "windows" of nonabsorption through which significant amounts of
radiation reach the ground. The first transmits ultraviolet and visible light, as well as infrared light or heat;
the second transmits radio waves. As a result, terrestrial organisms have evolved a number of pigments that interact with light in various ways: some capture light energy, some provide protection from light-induced damage, and some serve camouflage or signaling purposes.

Among these compounds are many conjugated polyenes, which play important roles as photoreceptors.
For every chemical compound, there are certain wavelengths of light whose quanta possess exactly the correct amount of energy to raise electrons from their ground state to higher-energy orbitals. For most organic compounds, these wavelengths are in the UV range. However, conjugated double bond systems stabilize the electrons, so that they can be excited by lower-frequency photons with wavelengths in the

visible spectrum. Such a pigment, known as a chromophore, will then transmit the "subtraction color," a color complementary to the one absorbed. For instance, carotene, a hydrocarbon compound with eleven conjugated double bonds, absorbs blue light and transmits orange. The wavelength that is absorbed
generally increases with the number of conjugated bonds; rings and side-chains also affect wavelength.

Wavelength Color Subtraction Color
480 nm blue orange
580 nm yellow violet
680 nm red green
Among the many biological molecules that are affected by light is DNA, the genetic material of living
organisms. DNA absorbs ultraviolet light, and may be damaged by UVC (< 280 nm) and UVB (280-315
nm). UVA (315-400 nm) and visible light can actually repair light-induced damage to DNA by a process called photorepair. For this reason, UVA, which also stimulates tanning, was once considered beneficial.
However, there is now increasing evidence that UVA can damage skin.

Two pigments are identical except for the lengths of their conjugated polyene chains. The first transmits yellow light and the second red.

What can be said about the sizes of the chromophores?

A person suffering from severe dehydration and starvation would NOT be expected to have elevated plasma concentrations for which of the following hormones?

Several techniques have been developed to determine the order of a reaction. The rate of a reaction cannot be predicted on the basis of the overall equation, but can be predicted on the basis of the rate-determining step. For instance, the following reaction can be broken down into three steps.

Step 1

(Slow)
Step 2

(fast)
Step 3

(fast)

Reaction 1
In this case, the first step in the reaction pathway is the rate-determining step. Therefore, the overall rate of the reaction must equal the rate of the first step, k1 [A] where k1 is the rate constant for the first step. (Rate constants of the different steps are denoted by kx , where x is the step number.)

In some cases, it is desirable to measure the rate of a reaction in relation to only one species. In a second-order reaction, for instance, a large excess of one species is included in the reaction vessel. Since a relatively small amount of this large concentration is reacted, we assume that the concentration essentially remains unchanged. Such a reaction is called a pseudo first-order reaction. A new rate constant, k', is

established, equal to the product of the rate constant of the original reaction, k, and the concentration of the species in excess. This approach is often used to analyze enzyme activity.

In some cases, the reaction rate may be dependent on the concentration of a short-lived intermediate. This can happen if the rate-determining step is not the first step. In this case, the concentration of the intermediate must be derived from the equilibrium constant of the preceding step. For redox reactions, the equilibrium can be correlated with the voltage produced by two half-cells by means of the Nernst equation.
This equation states that at any given moment:

Equation 1
When

Reaction 2
Note: R = 8.314 J/K-mol; F = 9.6485 x 104 C/mol.)

Catalysts are effective in increasing the rate of a reaction because they:

Researchers are currently trying to develop materials which could be used to replace damaged or destroyed human muscle tissue. One of the more promising avenues of research involves the use of substances that contract with the application of a small electric current.

Two physicists published an article relating to their work with Substance Q42, a material which contracts with the application of very small electric currents.

The atomic structure of the substance, they report, is designed so that the magnetic fields from each atom maintain a certain distance between adjacent atoms. With the application of an electrical current, the atoms' magnetic fields are dampened slightly, causing them to draw closer together. The extent to which it contracts is dependent upon the strength of the current passing through it, but will at any rate never exceed a 20% reduction in length.

Moreover, the physicists report, Substance Q42 essentially operated like a spring, but one which can compress itself. The force generated by a spring, Fs, is given by the following equation:

Fs = -kx,

where k is the spring of constant in N/m, and x is the distance of compression (or expansion, but that is irrelevant for this example, since Substance Q42 only compresses).

With this in mind, it is possible to calculate the feasibility of using Substance Q42 as a replacement for human muscle tissue. Assume a section of test Substance Q42 is hooked to a scalable electrical source.
The section is 10 cm long at its fully extended state, and 8 cm long when fully compressed due to an electrical current.

If an artificial arm muscle must be capable of doing 8 J work in 0.5 seconds time in order to efficiently substitute for human tissue, what average power must the section of Substance Q42 be capable of?

The lead-acid battery, also called a lead storage battery, is the battery of choice for starting automobiles. It contains 6 cells connected in series, each composed of a lead oxide cathode "sandwiched" between 2 lead anodes. Insulating separators are placed between the electrodes to prevent internal short-circuits.
Aqueous sulfuric acid is the electrolyte.

When the battery is being discharged, the following reaction takes place:

Reaction 1
The electrode reactions, both written as reductions, are shown in Table 1.

Table 1
Half-reaction
E?V)
PbO2(s) + SO42-(aq) + 4H+(aq) + 2e-
PbSO4(s) + 2H2O
PbSO4(s) + 2e- Pb(s) + SO42-(aq)
1.69

?.36

As a car operates, the battery is recharged by electricity produced by the car's alternator, an AC generator whose ultimate power source is the car's internal combustion engine. In spite of this, batteries eventually lose their power. The battery is said to be "dead" when Reaction 1 has proceeded completely to the right.

Which of the following occurs as the battery is being recharged?

A student conducts a chemical analysis of the components of a popular soft drink. The beverage label shows that the drink contains carbonated water, phosphoric acid, caffeine, and caramel color, but does not indicate the concentrations of these chemicals.

Dissolved carbon dioxide will react reversibly with water to form carbonic acid. In an attempt to analyze the beverage composition, the student conducts the following experiments on a one liter sample of the beverage.
Experiment 1
The sample is placed in a sealed beaker cooled to 10?C and a vacuum is created in the space above the beverage. The gas pumped from this space is passed through a solution of BaCl2, producing a white precipitate. The process continues until no more precipitate forms. The precipitate is dried and found to have a mass of 9.5 grams.
Experiment 2
The remaining solution left in the sealed beaker is then titrated with 0.01 M NaOH to give the titration curve shown in Figure 1.

Figure 1
The student uses the data from Experiment 1 and Experiment 2 to calculate the initial pH of the beverage.
If a significant quantity of precipitate was lost in the drying process of Experiment 1, the calculated pH:

Gauguin's attitude toward art marked a break from the past and a beginning to modern art. Like all Post-
Impressionist artists, he passed through an Impressionist phase but became quickly dissatisfied with the limitations of the style, and went on to discover a new style that had the directness and universality of a symbol and that concentrated on impressions, ideas and experiences. The beginning of his modern

tradition lay in his rejection of Impressionism. He considered naturalism an error to be avoided. He was preoccupied with suggestion rather than description, seeking to portray not the exterior, but the essence of things in their purest, simplest, and most primitive form, which could only be achieved through simplification of the form. He firmly believed throughout his life that "art is an abstraction" and that "this abstraction [must be derived] from nature while dreaming before it." One must think of the creation that will result rather than the model, and not try to render the model exactly as one sees it. This was the birth of "Synthetism" or rather Synthetist-Symbolic, as Gauguin referred to it, using the term "symbolic" to indicate that the forms and patterns in his pictures were meant to suggest mental images or ideas and not simply to record visual experience.

Symbolism flourished around the period of 1885 to 1910 and can be defined as the rejection of direct, literal representation in favor of evocation and suggestion. Painters tried to give a visual expression to emotional experiences, and therefore the movement was a reaction against the naturalistic aims of Impressionism. Satisfying the need for a more spiritual or emotional approach in art, Symbolism is characterized by the desire to seek refuge in a dreamworld of beauty and the belief that color and line in themselves could express ideas. Stylistically, the tendency was towards flattened forms and broad areas of color, and features of the movement were an intense religious feeling and an interest in subjects of death, disease, and sin.

Similarly, "Synthetism" involved the simplification of forms into large-scale patterns and the expressive purification of colors. Form and color had to be simplified for the sake of expression. This style reacted against the "formlessness" of Impressionism and favored painting subjectively and expressing one's ideas rather than relying on external objects as subject matters. It was characterized by areas of pure colors, very defined contours, an emphasis on pattern and decorative qualities, and a relative absence of shadows.

Gauguin's new art form merged these two movements and succeeded in freeing color, form, and line, bringing it to express the artists' emotions, sensibilities, and personal experiences of the world around them. His style created a break with the old tradition of descriptive naturalism and favored the synthesis of observation and imagination. Gauguin sustained that forms are not discovered in nature but in one's wild imagination, and it was in himself that he searched rather than in his surroundings. For this reason, he scorned the Impressionists for their lack of imagination and their mere scientific reasoning. Furthermore, Gauguin used color unnaturalistically for its decorative or emotional effect and reintroduced emphatic outlines. "Synthetism" signified for him that the forms of his pictures were constructed from symbolic patterns of color and linear rhythms and were not mere scientific reproductions of what is seen by the eye.

Dempsey, A., & Dempsey, A. (2010). Styles, Schools and Movements: The Essential Encyclopaedic Guide to Modern Art. London: Thames & Hudson.

Which of the following hypothetical pieces of evidence would diminish the author's claims about the importance of Gauguin?

Band theory explains the conductivity of certain solids by stating that the atomic orbitals of the individual atoms in the solid merge to produce a series of atomic orbitals comprising the entire solid. The closely-spaced energy levels of the orbitals form bands. The band corresponding to the outermost occupied subshell of the original atoms is called the valence band. If partially full, as in metals, it serves as a conduction band through which electrons can move freely. If the valence band is full, then electrons must be raised to a higher band for conduction to occur. The greater the band gap between the separate valence and conduction bands, the poorer the material's conductivity. Figure 1 shows the valence and conduction bands of a semiconductor, which is intermediate in conductivity between conductors and insulators.

Figure 1

When silicon, a semiconductor with tetrahedral covalent bonds, is heated, a few electrons escape into the conduction band. Doping the silicon with a few phosphorus atoms provides unbonded electrons that escape more easily, increasing conductivity. Doping with boron produces holes in the bonding structure, which may be filled by movement of nearby electrons within the lattice. When a semiconductor in an electric circuit has excess electrons on one side and holes on the other, electron flow occurs more easily from the side with excess electrons to the side with holes than in the reverse direction.

Figure 2

Why is iron a good conductor of electricity?

A researcher investigated the equilibrium between CO2, C, and CO as a function of temperature. The equation is given below:

CO2(g) + C(s) 2 CO(g)

Carbon dioxide, at 298 K and 1 atm, and an excess of powdered carbon were introduced into a furnace, which was then sealed so that pressure would increase as the temperature rose. The furnace was heated to, and held constant at, a predetermined temperature. The pressure within the furnace chamber was recorded after it had remained unchanged for one hour. The table below shows the pressures recorded for a series of temperatures together with the pressures expected if no reaction had taken place.
Table 1

How are the values of Pe calculated?

A local politician starts a task force to reduce prejudice and hate crimes, and the task force provides recommendations for increased access to education, paid community improvement projects open to people from different, possibly conflicted, groups, and stricter anti-hate ordinances to be passed at the local level. These recommendations are based on:

I. Self-esteem hypothesis
II. Contact hypothesis
III. Hypothesis
IV. Legal hypothesis

Rancidity involves:

The equation of state of an ideal gas is given by the ideal gas law:
PV = nRT
where P is the pressure, V is the volume, n is the number of moles of gas, R is the ideal gas constant, and T is the temperature of the gas. The gas particles in a container are constantly moving at various speeds.
These speeds are characterized by the Maxwell shown in the figure below.

If two particles collide, their velocities change. However, if the gas is in thermal equilibrium, the velocity distribution of the gas as a whole will remain unchanged by the collision.

The average kinetic energy (E) of a gas particle is given by:

Equation 1
where m is the mass of one particle and u is the root mean square speed (rms speed) of the gas particles:

where N is the number of gas particles; this is different from the average speed). For an ideal gas, the
kinetic energy of all the particles is:

Equation 2
where n is the number of moles of gas. Combining these equations gives:

Equation 3
where M is the molar mass of the gas particles.

The average distance a particle travels between collisions is known as the mean free path l. Intuitively, the mean free path (mfp) could be expected to be larger for gases at low pressure, since there is a lot of space between particles. Similarly, the mfp should be larger when the gas particles are small. The following expression for the mfp shows this to be correct.

Equation 4
In this equation, s is the atomic diameter (typically on the order of 10?), k is the Boltzmann constant, and P is the pressure. In addition to colliding with one another, gas particles also collide with the walls of their container. If the container wall has a pinhole that is small compared to the mfp of the gas, and a pressure differential exists across the wall, the particles will effuse (or escape) through this pinhole without disturbing the Maxwellian distribution of the particles. The rate of effusion can be described by:

Equation 5
Where neff is the number of moles of effusing particles, A is the area of the pinhole, p and p1 are the
pressures on the inside and outside of the container wall respectively, and p>p1.

Which of the following gives values for both standard temperature and pressure?

Studies of photosynthesis began in the late eighteenth century. One scientist found that green plants produce a substance (later shown to be oxygen) that supports the flame of a candle in a closed container.
Several years later it was discovered that a plant must be exposed to light in order to replenish this flame-

sustaining "substance". Soon another discovery showed that the oxygen is formed at the expense of
another gas, carbon dioxide.

In 1804, de Saussure conducted experiments revealing that equal volumes of carbon dioxide and oxygen are exchanged between a plant and the air surrounding it. De Saussure determined that the weight gained by a plant grown in a pot equals the sum of the weights of carbon derived from absorbed carbon dioxide and water absorbed through plant roots. Using this information, de Saussure was able to postulate that in photosynthesis carbon dioxide and water combine using energy in the form of light to produce carbohydrates, water, and free oxygen. Much later, in 1845, scientists' increased understanding of concepts of chemical energy led them to perceive that, through photosynthesis, light energy is transformed and stored as chemical energy.

In the twentieth century, studies comparing photosynthesis in green plants and in certain sulfur bacteria yielded important information about the photosynthetic process. Because water is both a reactant and a product in the central reaction, it had long been assumed that the oxygen released by photosynthesis comes from splitting the carbon dioxide molecule. In the 1930s, however, this popular view was decisively altered by the studies of C. B. Van Niel. Van Niel studied sulfur bacteria, which use hydrogen sulfide for photosynthesis in the same way that green plants use water, and produce sulfur instead of oxygen. Van Niel saw that the use of carbon dioxide to form carbohydrates was similar in the two types of organisms.
He reasoned that the oxygen produced by green plants must derive from water -- rather than carbon dioxide, as previously assumed -- in the same way that the sulfur produced by the bacteria derives from hydrogen sulfide. Van Niel's finding was important because the earlier belief had been that oxygen was split off from carbon dioxide, and that carbon then combined with water to form carbohydrates. The new postulate was that, with green plants, hydrogen is removed from water and then combines with carbon dioxide to form the carbohydrates needed by the organism.

Later, Van Niel's assertions were strongly backed by scientists who used water marked with a radioactive isotope of oxygen in order to follow photosynthetic reactions. When the photosynthetically-produced free oxygen was analyzed, the isotope was found to be present.

According to the passage, C. B. Van Niel's experiments:

Hypoxia refers to a physiological condition in which the body lacks sufficient oxygen for normal cellular functioning. Prolonged hypoxia generally leads to an inhibition of mental capacity and a reduction in the

work capacity of muscle. Severe cases of hypoxia can lead to coma or even death. Depending on the cause, hypoxia can be classified into four general types:

Hypoxic hypoxia is a type of hypoxia that occurs when the partial pressure of oxygen in the blood is too low. For example, climbers at high altitude, where the air contains less oxygen, might experience hypoxic hypoxia because the partial pressure of oxygen in the air inhaled is very low, leading to insufficient partial pressure of oxygen in the blood.

Anemic hypoxia describes a diminished ability of the blood to transport oxygen. Several factors can influence the oxygen-carrying capacity of the blood. Primary causes of anemic hypoxia include a lower than normal number of functional erythrocytes or an insufficient quantity of hemoglobin, the oxygen-carrying molecules of the blood. Abnormal hemoglobin can also decrease the blood's capacity to carry oxygen and lead to anemic hypoxia.

Ischemic hypoxia is caused by a decreased delivery of blood to the tissues. Localized circulatory deficiencies, such as blood clots, and global circulatory deficiencies, such as heart failure, decrease the delivery of blood to the tissues, and can therefore cause ischemic hypoxia.

Histotoxic hypoxia results from the inability of cells to utilize the oxygen available in the blood. Causes of histotoxic hypoxia include the poisoning of cellular enzymes involved in aerobic respiration, as well as the decreased metabolic capacity of the oxidative enzymes due to vitamin deficiency. Cyanide poisoning causes histotoxic hypoxia by blocking the action of cytochrome oxidase in the electron transport chain so that tissues cannot use oxygen even though it is available.

A patent foramen ovale occurs when an infant's foramen ovale does not close completely at birth. Based on the information presented in the passage, this can lead to:

Myoclonic epilepsy and ragged-red fiber (MERRF) is an extremely rare disorder that affects neuromuscular systems. MERRF results from a mutation in mitochondrial DNA (mtDNA) that impairs protein synthesis, oxygen consumption, and energy production.

When an affected male and a normal female reproduce, which of the following best predicts the expected phenotypic ratios of the offspring?

An automatic external defibrillator (AED) is simply a series of capacitors used to store a very large charge, which is then discharged through the patient's chest in a short time.
If the capacitor in an AED is fully charged and the AED is no longer connected to the power source, what will happen to the energy stored in the AED if the dielectric (k = 1.5) is removed?

Arginine is one of the 20 most common natural amino acids. Most healthy people do not need to supplement with arginine because the body usually produces sufficient quantities. The pathway for arginine synthesis was studied using cells from a red bread mold. This natural form of arginine is illustrated below.

The red bread mold Neurospora crassa grows well on a cultural plate with "minimal" medium which is a fluid containing only a few simple sugars, inorganic salts, and vitamin. Neurospora that grows normally in nature (wild type) has enzymes that convert these simple substances into the amino acids necessary for growth. Mutating any one of the genes that makes an enzyme can produce a Neurospora strain that cannot grow on minimal medium. The mutant would only grow if the enzyme product were to be added as a supplement. On the other hand, if a "complete" medium is provided, containing all required amino acids, then Neurospora would grow, with or without mutation.

Figure 1 A synthesis pathway for the amino acid arginine. Each gene in italics in the diagram produces one enzyme necessary for the synthesis of this essential amino acid required for growth.

Table 1 Growth response of mutant strains in "minimal" media with supplements (ornithine, citrulline, argininosuccinate, and arginine) as indicated. Strain growth is indicated by (+) and no strain growth is indicated by (-).

Consider tetrapeptides containing 2 equivalents each of the natural forms of arginine and proline.

How many different linear tetrapeptides can be synthesized?

The automobile airbag was designed to inflate upon impact and decrease the risk of injury to drivers and passengers. Among the challenges to its development was the need to find a reliable inflation mechanism that was sufficiently rapid, controllable, and nontoxic. Prototypes employing compressed gases failed to meet these criteria. Researchers thus turned their attention to chemical alternatives.

The ideal inflatant requires a chemical reaction in which the reactants are stable and relatively dense in the condensed phase while the products are mostly or completely gaseous at ambient temperature and pressure. Additionally, the ideal chemical reaction would require a low activation energy and have a high kinetic rate constant, without the large exothermicity characteristic of most such reactions. Traditional explosives such as nitroglycerin, C3H5N3O9(l), were rejected almost immediately because of the extremely exothermic nature of their conversion. Benign solids such as calcium carbonate, CaCO3 , were similarly rejected, because of their large activation requirements. The desired attributes were finally found in sodium azide, NaN3, a stable, dense, ionic solid which rapidly decomposes into elemental sodium and nitrogen gas when ignited by an electrical impulse.

Reaction 1

The gas generating mixture includes excess KNO3 which reacts with the sodium metal from Reaction 1 to produce additional N2 and potassium and sodium oxides (Reactions 2 and 3). These oxides react with SiO2 to produce a non-toxic and stable alkaline silica (glass).

Reaction 2

Reaction 3

A researcher wishes to make the decomposition of sodium azide (Reaction 1) less favorable.

Which of the following adjustments to the reaction would NOT drive it to the left?

Which option occurs as a result of inbreeding?

Agonistic behavior, or aggression, is exhibited by most of the more than three million species of animals on this planet. Animal behaviorists still disagree on a comprehensive definition of the term, but aggressive behavior can be loosely described as any action that harms an adversary or compels it to retreat.
Aggression may serve many purposes, such as food gathering, establishing territory, and enforcing social hierarchy. In a general Darwinian sense, however, the purpose of aggressive behavior is to increase the individual animal's -- and thus, the species' -- chance of survival.
Aggressive behavior may be directed at animals of other species, or it may be conspecific -- that is, directed at members of an animal's own species. One of the most common examples of conspecific aggression occurs in the establishment and maintenance of social hierarchies. In a hierarchy, social
dominance is usually established according to physical superiority; the classic example is that of a pecking
order among domestic fowl. The dominance hierarchy may be viewed as a means of social control that

reduces the incidence of attack within a group. Once established, the hierarchy is rarely threatened by disputes because the inferior animal immediately submits when confronted by a superior. Two basic types of aggressive behavior are common to most species: attack and defensive threat. Each type involves a particular pattern of physiological and behavioral responses, which tends not to vary regardless of the stimulus that provokes it. For example, the pattern of attack behavior in cats involves a series of movements, such as stalking, biting, seizing with the forepaws and scratching with the hind legs, that changes very little regardless of the stimulus -- that is, regardless of who or what the cat is attacking.
The cat's defensive threat response offers another set of closely linked physiological and behavioral patterns. The cardiovascular system begins to pump blood at a faster rate, in preparation for sudden physical activity. The eyes narrow and the ears flatten against the side of the cat's head for protection, and other vulnerable areas of the body such as the stomach and throat are similarly contracted. Growling or hissing noises and erect fur also signal defensive threat. As with the attack response, this pattern of responses is generated with little variation regardless of the nature of the stimulus.
Are these aggressive patterns of attack and defensive threat innate, genetically programmed, or are they learned? The answer seems to be a combination of both. A mouse is helpless at birth, but by its 12th day of life can assume a defensive threat position by backing up on its hind legs. By the time it is one month old, the mouse begins to exhibit the attack response. Nonetheless, copious evidence suggests that
animals learn and practice aggressive behavior; one need look no further than the sight of a kitten playing
with a ball of string. All the elements of attack -- stalking, pouncing, biting and shaking -- are part of the game which prepares the kitten for more serious situations later in life.

Which of the following would be most in accord with the information presented in the passage?

Synthetic dyes constitute a commercially significant area of organic chemistry. The color producing properties of these compounds are the result of highly delocalized electron systems giving rise to electronic transitions whose absorptions occur in the visible region. Most commercially useful dyes can be classified as one of three types -- anthraquinones, azo dyes, or triarylmethyl salts. Examples of each type are illustrated in Figure 1.

Figure 1

In order for a dye to be useful in the fabric industry, it must have sufficient affinity for the polymeric fibers of
which the material is composed; the dye must not only impart a color to the fabric, but must also do so in a
relatively permanent manner (color fastness). Proper design of synthetic polymers requires the placement of acidic or basic side chains along the polymer backbone such that binding sites are available for dying.
Similarly, dyes must be produced not only with the appropriate color-producing structure, but also with an affinity for the fabric in question. The structural units of several common synthetic fibers are shown in Figure 2.

Figure 2

Nylon, Dacron, and many other synthetic fibers are produced via condensation reactions.

Which of the following would be the best starting materials for the production of nylon 66?

The force restraining an object's motion on an inclined plane:

Early experimentation on the single-celled organism Acetabularia led to important discoveries about the role of the nucleus in regulating cell function. Acetabularia is an enormous single cell with three distinct regions: a cap, a root-like rhizoid, and a stalk which connects the two. The following experiments were conducted to study the development of the cell:

Experiment 1

The stalk of an Acetabularia was cut, fragmenting the cell. The fragment which included the cap died shortly afterwards while the fragment containing the rhizoid regenerated to form a complete Acetabularia.

Experiment 2

The nucleus from Acetabularia mediterranea, which has a flat cap, was transplanted into Acetabularia crenulata, which has a tufted cap, following removal of the Acetabularia crenulata nucleus. The Acetabularia crenulata cap eventually assumed the flat shape.

Experiment 3

The nucleus of Acetabularia mediterranea was removed from the young cell before it first formed a cap. A normal cap formed several weeks later. The cell proved to be inviable and died shortly thereafter.

Experiment 4

A young Acetabularia was fractioned into a number of portions before it first formed a cap. Several weeks later, both the portion containing the nucleus and the portion containing the apical tip of the stalk formed caps. The other portions did not form caps.

Which of the following conclusions can be logically drawn from the fact that the Acetabularia segment containing the rhizoid regenerated a complete and viable Acetabularia in Experiment 1?

Morphine alkaloids derived from the opium poppy have long been used as analgesics. Codeine, the methyl ether of morphine, is a naturally occurring alkaloid with medicinal properties very similar to those of morphine. Thousands of derivatives of morphine have been synthesized and tested for their biological effects. For example, the diacylated derivative of morphine, heroin, is a highly addictive drug. Much effort has gone into understanding how morphine and its derivatives function.

Studies have shown that certain common structural features of alkaloids are required for the compound to exhibit biological activity. These structural requirements are summarized by the so called "morphine rule": Demerol and methadone, shown in Figure 2, are two synthetic alkaloids designed to satisfy the "morphine rule." Synthetic alkaloids such as these have been found to mimic certain physiological properties of morphine and its derivatives, and have found pharmacological application due to other, more desirable biological effects. Methadone has been used widely in the United States and Great Britain as a treatment
for heroin addiction; it reduces the physical symptoms accompanying withdrawal without producing many
of the other effects of heroin.

Meperidine
(demerol)
Figure 2

Which of the following compounds would be most likely to have morphine-like biological effects?

Many nutrients required by plants exist in soil as basic cations:

A soil's cation-exchange capacity is a measure of its ability to adsorb these basic cations as well as exchangeable hydrogen and aluminum ions. The cation-exchange capacity of soil is derived from two sources: small clay particles called micelles consisting of alternating layers of alumina and silica crystals, and organic colloids.

Replacement of + and + by other cations of lower valence creates a net negative charge within the inner layers of the micelles. This is called the soil's permanent charge. For example, replacement of an atom of aluminum by calcium within a section where the net charge was previously zero, as shown below, produces a net charge of ?, to which other cations can become adsorbed.

Figure 1

A pH-dependent charge develops when hydrogen dissociates from hydroxyl moieties on the outer surfaces of the clay micelles. This leaves negatively-charged oxygen atoms to which basic cations may adsorb.
Likewise, a large pH-dependent charge develops when hydrogen dissociates from carboxylic acids and phenols in organic matter.
In most clays, permanent charges brought about by substitution account for anywhere from half to nearly all of the total cation-exchange capacity. Soils very high in organic matter contain primarily pH-dependent charges. In a research study, three samples of soil were leached with a 1 N solution of neutral KCl, and the displaced A13+ and basic cations measured. The sample was then leached again with a buffered solution of BaCl2 and triethanolamine at pH 8.2, and the displaced H+ measured. Table 1 gives results for three soils tested by this method.
Table 1

Due to the buffering effect of the soil's cation exchange capacity, just measuring the soil solution's pH will

not indicate how much base is needed to change the soil pH. In another experiment, measured amounts of acid and base were added to 10-gram samples of well-mixed soil that had been collected from various locations in a field. The volumes of the samples were equalized by adding water. The results were recorded in Figure 2.

Figure 2.

The amount of soil on a particular one-acre field down to a depth of one furrow slice weighs 9 ?105 kilograms.
Based on Figure 2, how many kilograms of CaCO3 would have to be added to this field to raise the pH from 5 to 6?

According to the reaction coordinate diagram shown below, which of the following forward reactions would proceed most rapidly at high temperatures?

If a man having blood group AB marries a woman who is heterozygous for blood group, what is the probability of their first child having blood group B?

When Gwendolyn Brooks published her first collection of poetry A Street In Bronzeville in 1945 most reviewers recognized Brooks' versatility and craft as a poet. Yet, while noting her stylistic successes few of her contemporaries discussed the critical question of Brooks' relationship to the Harlem Renaissance. How had she addressed herself, as a poet, to the literary movement's assertion of the folk and African culture, and its promotion of the arts as the agent to define racial integrity?
The New Negro poets of the Harlem Renaissance expressed a deep pride in being Black; they found
reasons for this pride in ethnic identity and heritage; and they shared a common faith in the fine arts as a
means of defining and reinforcing racial pride. But in the literal expression of this impulse, the poets were either romantics, or realists and, quite often within the same poem, both. The realistic impulse, as defined best in the poems of McKay's Harlem Shadows (1922), was a sober reflection upon Blacks as second class citizens, segregated from the mainstream of American socio-economic life, and largely unable to realize the wealth and opportunity that America promised. The romantic impulse, on the other hand, as defined in the poems of Sterling Brown's Southern Road (1932), often found these unrealized dreams in the collective strength and will of the folk masses. In comparing the poems in A Street in Bronzeville with various poems from the Renaissance, it becomes apparent that Brooks brings many unique contributions to bear on this tradition. The first clue that A Street In Bronzeville was, at its time of publication, unlike any other book of poems by a Black American is its insistent emphasis on demystifying romantic love between Black men and women. During the Renaissance, ethnic or racial pride was often focused with romantic idealization upon the Black woman. A casual streetwalker in Hughes' poem, "When Sue Wears Red," for example, is magically transformed into an Egyptian Queen. In A Street In Bronzeville, this romantic impulse runs headlong into the biting ironies of racial discrimination. There are poems in which Hughes, McKay and Brown recognize the realistic underside of urban life for Black women. But for Brooks, unlike the Renaissance poets, the victimization of poor Black women becomes not simply a minor chord but a predominant theme.
...Brooks' relationship with the Harlem Renaissance poets, as A Street in Bronzeville ably demonstrates, was hardly imitative. As one of the important links with the Black poetic tradition of the 1920s and 1930s, she enlarged the element of realism that was an important part of the Renaissance world-view. Although her poetry is often conditioned by the optimism that was also a legacy of the period, Brooks rejects outright their romantic prescriptions for the lives of Black women. And in this regard, she serves as a vital link with the Black Arts Movement of the 1960s that, while it witnessed the flowering of Black women as poets and

social activists as well as the rise of Black feminist aesthetics in the 1970s, brought about a curious revival of romanticism in the Renaissance mode.

Suppose that a recently-discovered collection of Gwendolyn Brooks' poems contained female protagonists that embodied the ideal woman. This information would:

An automobile reaches a velocity of 30 m/s after accelerating at 4 ms-2 for 5 seconds.

What was its initial velocity?

When electric current passes through an aqueous solution, which of the following ionic migrations is correct?

When humans are submerged in water, the mammalian dive reflex acts to alter circulation. Heart rate decreases, blood flow to the extremities is reduced, and mean arterial blood pressure is increased. These accomodations lead to:

Aclown stands with her toes touching a fun house mirror with a convex bottom and a concave top.

Which of the following best describes the distortion of the clown's image as she walks away from the mirror?

...Squeaking sand produces sounds with very high frequencies -- between 500 and 2,500 hertz, lasting less than a quarter of a second. The peals are musically pure, often containing four or five harmonic overtones. Booming sand makes louder, low-frequency sounds of 50 to 300 hertz, which may last as long as 15 minutes in larger dunes (although typically they last for seconds or less). In addition, they are rather noisy, containing a multitude of nearby frequencies. Booms have never been observed to contain more than one harmonic of the fundamental tone.
These dramatic differences once led to a consensus that although both types of sand produce acoustic emissions, the ways in which they do so must be substantially different.... In the late 1970s, however, Peter K. Haff, then at the California Institute of Technology, produced squeaks in booming sand, suggesting a closer connection between the two.
Both kinds of sand must be displaced to make sounds. Walking on some sand, for example, forces the sand underfoot to move down and out, producing squeaks. In the case of booming sand, displacement occurs during avalanches. It is within the avalanche that sound begins and where the answers must be hiding.
Before an avalanche can occur, winds must build a dune up to a certain angle, usually about 35 degrees for dry desert sand. Once an angle is achieved, the sand on the leeward side of the dune begins to slump.
Intact layers of sand slip over the layers below, like a sheared deck of cards. At the same time, the individual grains in the upper layers tumble over the grains underneath, momentarily falling into the spaces between them and bouncing out again to continue their downward journey. Their concerted up-and-down motion is believed to be the secret source of sound. Fully developed avalanches, in which sliding plates of sand remain intact for most of their motion, have the greatest acoustic output. In some places, where large amounts of sand are involved, booming can be heard up to 10 kilometers away.
Because it is caused by large volumes of shearing sand, the roaring is also loud. In fact, sounds made by booming sand can be nearly deafening, and the vibrations causing them can be so intense that standing in their midst is nearly impossible.
A good place to start in exploring the vibrational properties of sand is with the grains themselves. The mean diameter of most sand grains, whether acoustically active or not, is about 300 microns. Usually the grains in a booming dune are very similar in size, especially near the leeward crest, where the sound most
often originates; such uniformity allows for more efficient shearing. Otherwise, the smaller grains impede
the smooth motion of the larger ones. Similar sizes do not alone allow sand to boom. On the contrary, the booming sands of Korizo and Gelf Kebib, also in Libya, feature an uncharacteristically broad range of particle sizes. Moreover, silent dune sand often contains grains somewhat similar to nearby booming sand.
Grains of booming sand also tend to have uncommonly smooth surfaces, with protrusions on the scale of
mere microns. Booming dunes are often found at the downwind end of large sand sources; having
bounced and rolled across the desert for long distances, the sand grains in these dunes are usually highly polished. Over time a grain can also be polished by repeated shifts within a moving dune. And squeaking sand as well tends to be exceptionally smooth.... ...Another important factor is humidity, because moisture can modify the friction between grains or cause sand to clump together, thus precluding shearing. Sounds occur in those parts of the dune that dry the fastest. Precipitation may be rare in the desert, but dunes retain water with remarkable efficiency. Sand near the surface dries quickly, however, and sand around a dune's crest tends to dry the fastest.

A dune is found to be comprised of smooth grains and produces sounds that last less than a second.

What further information, if any, would enable one to unambiguously characterize the sand as squeaking sand?