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…From a geological point of view, the Mediterranean is a tectonically mobile land-enclosed depression – small(about 3,000,000 square kilometers) in comparison to the major world oceans…Immediately obvious on allcharts is the highly variable topography and relief of both the seafloor and adjacent borderland. The coastline ishighly irregular and continental shelves, though generally narrow, are well developed off the major river deltas(Nile, Rhone, Po, and Ebro). Moreover, the deep-sea basins and trenches have distinctive relief, with basinplains ranging in depth from less than 1,000 meters to more than 4,000…Observation that rocks dredgedoffshore are similar to those on land raised a fundamental concept – the key to understanding Mediterraneanhistory lies in the adjacent emerged land masses, and vice-versa……Early paleographic reconstructions showed that the once-open communication with the Atlantic deterioratedduring the upper Miocene. Water-mass exchange continued for a while in the Rif Strait, but then ceasedcompletely prior to the beginning of the Pliocene……High relief near what is now the Strait of Gibraltar served as a barrier to the exchange of waters with theAtlantic. Exposed to a hot and dry climate, water evaporated and the then-dry basin elicited comparison with agigantic Death Valley…Microfossil studies suggested that the depth of the Mediterranean basin at these timeshad been “deep.” Estimates suggested a dry seafloor as far as 2,000 meters below ocean level… As aresponse to suddenly lowered sea level, rivers feeding the Mediterranean and canyons on the now-dry seafloorbegan a geologically dramatic phase of erosion. Deep, Grand Canyon-like gorges of the Nile and Rhone rivers,presently buried on land, were apparently cut during a great drawdown of water – when the Mediterranean floorlay exposed 1,000 meters or more below its present level…The sudden flooding through a gigantic waterfall atGibraltar drowned the exposed basin floor. These falls would have been 1,000 times bigger than NiagaraFalls…This flooding event is recorded by the Miocene Pliocene boundary, a time when open marine faunalassemblages were suddenly reintroduced from the Atlantic……Geological theories usually fall at a glacial pace into a sea of controversy, and this one is no exception. Today– charging that proof for the theory is lacking – many scientists believe that the Med always contained saltwater,with only the depth of the seafloor and the water being in question… Some of the tenets on which the theorywas formulated are, if not defective, very seriously in question. To interpret their findings, a respectable numberof geologists studying the surrounding emerged borderland as well as subsea sections indicate that alternative,more comprehensive concepts must be envisioned……It is not realistic to envision the Mediterranean seafloor of about 5 million years ago as a desert at 3,000meters below present ocean level. Several years ago…the Mediterranean [was compared] to a complexpicture-puzzle that comprises numerous intricate pieces, many of which are already in place. A general imageis emerging, although gaps in some areas of the picture remain fuzzy and indistinct.It can be inferred from the passage that geological theories tend to:Section: Verbal Reasoning 

The sexual reproduction in Rhizopus isSection: Biological Sciences 

What happens to brain waves as an organism falls asleep? Section: Physical Sciences 

In an acetyl molecule, two atoms of carbon are bonded by: Section: Physical Sciences 

Arginine is one of the 20 most common natural amino acids. Most healthy people do not need to supplementwith arginine because the body usually produces sufficient quantities. The pathway for arginine synthesis wasstudied 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 fluidcontaining 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 onminimal medium. The mutant would only grow if the enzyme product were to be added as a supplement. On theother hand, if a "complete" medium is provided, containing all required amino acids, then Neurospora wouldgrow, with or without mutation.Figure 1 A synthesis pathway for the amino acid arginine. Each gene in italics in the diagram produces oneenzyme 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 indicatedby (−).Which of the following is NOT an accurate description of naturally-occurring arginine?Section: Physical Sciences