Free Admission Tests GMAT Practice Exam with Questions & Answers | Set: 3

Mathematical principles of probability entail that for any future event, the probability that it will occur Is at least as great as the probability that both it and some other given event will occur. Consider, for example, the following statements that were shown to subjects in a 1998 study.

X The percentage of adolescent smokers In Texas will decrease at least 15% from current levels by September 1, 1999.

Y The cigarette tax in Texas will increase by $1.00 per pack in 1999.

Z The cigarette tax in Texas will increase by $1.00 per pack in 1999, and the percentage of adolescent smokers in Texas will decrease at least 15% from current levels by September 1, 1999.

Z("Kand X") could not have been more probable than X. Nevertheless, many of the subjects judged Zto be more probable than X. This mistaken form of reasoning, displayed with surprising frequency in various studies in addition to the 1998 study, is known as the "conjunction fallacy."

A number of researchers have offered alternative explanations for the seeming manifestations of the mistake, thus arguing that the fallacy is less widely committed than the various studies would indicate. Some have claimed that research subjects can take "probability" in a sense that does not conform to the mathematical principles of probability. Detailed descriptions of some such conceptions of "probability" have been developed under the names of "confirmation" and "support." Other researchers would claim, correctly, that subjects shown Z(" Kand X") and ^simultaneously will sometimes think of Xas involving the negation of Y—as a claim that the percentage of adolescent smokers in Texas will decrease, but without the $1.00 increase in the cigarette tax.

However, although the subjects in the 1998 study were to consider Xand Z simultaneously, the statements were presented in terms of bets rather than explicit requests for judgments of relative probability. Subjects were asked to choose between Zand X, with a chance of winning $50.00 if the chosen statement turned out to be true. Terms such as "most probable," "likely," etc., were thus avoided, and the interpretation of X\n conjunction with the negation of Kwas thereby eliminated. And with these alternative explanations eliminated, many of the subjects nonetheless bet on Zrather than X:

Despite overall physiological bilateral symmetry, many species exhibit

lateralized biases, i.e., preferences for right- or left-oriented behavior. When

approaching prey, for example, some predator species favor their right eye; some

prey species respond more quickly when their left eye detects a predator. Similar

behavioral asymmetries occur in humans. Most notable is right- and lefthandedness; less notable is the tendency to turn right when entering a room.

Paul Farnsworth found that more successful students tended to choose seats near

the front, a little to the right. He argued that external factors such as teacher

location might have affected this lateral bias. But it is now known that processing

differences between the two brain hemispheres can also contribute to behavioral

asymmetries,

George Karev found that when presented with a movie theater seating

diagram, right-handed people were more likely than left-handed people to choose

a seat on the right, facing front. But he hypothesized that, since the right

hemisphere processes visuospatial and emotional information, the people who

chose right-side seats did so because that would put the screen in their left visual

field, optimizing information flow to the right hemisphere.

Although the right hemisphere is thought to be dominant in processing

emotion, some evidence suggests that the left hemisphere plays a role. The

valence model proposes that the left and right hemispheres process positive and

negative emotion respectively, while the approach-withdrawal model posits that

the left hemisphere processes emotion expressed in approach behavior and the

right hemisphere processes emotion expressed in withdrawal behavior.

Victoria Harms and colleagues suggested that since a paper seating plan was

used in the theater-seating studies by Karev and others, the exhibited preference

might be due simply to handedness: people choose the same side of the paper as

their favored hand. Consequently, the Harms research was designed to study

choices in an actual movie theater. Also, hoping to distinguish between various

explanations, they studied seating choices for comedies (presumed to contain

Positive emotional content), dramas (presumed to contain negative emotional

content), and documentaries (presumed to have balanced emotional content).

They found significant—though not universal—preference for seats on the right,

facing front, regardless of movie genre and of handedness.

What makes a rhinoceros look like a rhinoceros, or a petunia like a petunia? Understanding the basis of the generation of the forms, patterns, or shapes of complex organisms is a principal subject of biologist Gerald Edelman's stimulating book Topobiology, which explores the links among the development, evolution, form, and function of organisms.

In older scientific language, one could say that Edelman has brought a new dimension to morphology, the study of the form and shape of animate and plants, and to histology, the study of the minute structure of tissues. The major thrust of his book te what he calls a morphoregulatory hypothesis, which can be described as the outline of a molecular basis for the formation of pattern, involving three types of genes. In the morphoregulatory sequence, morphoregulatory genes control the production of molecules that cause the formation of clusters of cells. When the cell dusters begin to communicate, they activate another type (selector genes) that then select and switch on a third type of gene (historegulatory genes).

In the organisms they have studied, Edelman and his colleagues have found cell adhesion molecules (resulting from morphoregulatory gene action) that are attached to the surface of different cells and link them in clusters. These molecules can appear at different times in the development of a multicellular system, and at various specific sites on the cells. Furthermore, their chemical structure can vary. This tremendous variation allows a great flexibility in the kinds of linkages the molecules effect.

A second class of adhesion molecules plays a comparable role In attaching cells to the developing scaffolding of filaments that lie outside cells. Also of particular interest to researchers are what are called cell Junction molecules, composed of clusters of proteins providing small channels from the inside of one cell to the Inside of another. These three types of molecules facilitate a kind of conversation among eels that determines the course of development of organisms. It has been possible to demonstrate how Important these molecules are by treating tissues with agents that block their functions, thus effectively and drastically changing the organism's development.

The following is based on an article published in 2012.

Most linguists believe proto-Indo-European, the ancestor of all Indo-European

languages, was the language of chariot-driving pastoralists who spread through

Eurasia from steppes north of the Black Sea about 4,000 years ago. But a

competing theory is that proto-Indo-European was spoken by farmers in Anatolia

(Asia Minor) about 9,000 years ago, and spread from there along with agriculture.

To evaluate these hypotheses, researchers statistically compared IndoEuropean languages' vocabularies. Languages with more similar vocabularies are

probably more closely related, sharing more recent common ancestors.

Combining the vocabulary statistics with the known dates when certain languages

split, and with their known geographical ranges, a computer calculated the most

likely relationships among all Indo-European languages and concluded that protoIndo-European probably originated in Anatolia 9,000 years ago.

Disputing this conclusion, skeptics argue that most Indo-European languages

are similar in their words pertaining to chariots and wagons, suggesting protoIndo-European split into daughter languages only after chariots and wagons were

invented. No archaeological evidence indicates that chariots and wagons existed

before 5,500 years ago. Furthermore, proto-Indo-European had words for "horse"

and "bee" and lent many words to proto-Uralic, the mother language of Finnish

and Hungarian. The steppes north of the Black Sea were far closer than Anatolia

to areas where proto-Uralic was spoken, and had more abundant wild horses and

bees.

Soil salinization—the process by which soil acquires excess soluble salt, adversely affecting pasture or crop growth—is regarded as Australia's most serious environmental problem. Cope, whose 1958 investigation is considered the earliest survey of salt-affected areas in Victoria, hypothesized that surplus rainwater mobilized soluble salt stored in the permeable layer of soil, causing it to accumulate above an impermeable layer and then discharge downslope or onto a valley floor. In the late 1970s, however, Jenkin identified saline water underground as the main and immediate (though not ultimate) source of the salt, and hypothesized that the spread of salinity resulted from a rise in that groundwater. He attributed the rise to a decrease in coverage by water-absorbing trees and other vegetation at some ill-defined point in Australia's post-settlement history.

However, more-recent research suggests there was no rise in post-settlement groundwater levels. Furthermore, soil salinity probably antedated European settlement: early cartographic evidence indicates that some streams were saline when Europeans arrived. Dahlhaus suggests that salt accumulation resulted from marine incursions several million years ago, when parts of Victoria may have been submerged—as well as from transport of salt from the sea by wind and rain. Dahlhaus also notes that various minerals dissolved in groundwater by weathering may have produced salt.

United States Geological Survey scientists have found that a cooling in Pacific Ocean temperatures ed to increases in ecologically threatening phytoplankton blooms m San Francisco Bay, California. The declining temperatures took place off the coast of California between 1999 and 2004. The occurrence of these blooms is surprising because such blooms are normally associated with increases n the amount of nutrients, such as nitrogen and phosphorus, entering estuaries from such sources as wastewater treatment plants and agricultural fields. In this case, the bay's phytoplankton blooms occurred during a period of decreasing nutrient concentration and inputs.

The scientists discovered the effects of the cold Pacific temperatures by using biological and water-quality data collected over twenty-five years. The colder temperatures caused changes in the types, abundance, and migration patterns of marine life into the San Francisco Bay from coastal ocean waters. For example, marine life, such as fish, shrimp, and crabs, migrated to the warmer waters thot are found in the bay.

The migrations increased the numbers of predators such as bay shrimp and Dungeness crabs that eat filter feeders, such as clams. Clams can filter large quantities of phytoplankton from the bay's water, which can prevent phytopldnklon blooms. With the increase in predators, there wds d corresponding

decrease In clam populations and an increase in phytoplarkton.