IELTS リーディング 模擬試験 1

【標題清單 List of Headings】 i. An internal mechanism for measuring distance ii. Navigating by detecting invisible light patterns iii. The physical limitations of desert predators iv. An extraordinary survival challenge in a barren landscape v. How human maritime navigation inspired insect research vi. Local cues for the final stage of the journey vii. The evolutionary advantages of risky foraging viii. The effect of changing wind patterns on nest odors ──────── [A] The desert of North Africa presents one of the most hostile environments on Earth, characterized by shifting sands, intense solar radiation, and temperatures that can exceed 50 degrees Celsius. In this barren landscape, the salt pans of Tunisia offer virtually no landmarks, such as trees or rocks, to help animals find their way. Most desert creatures seek shelter deep underground during the hottest hours of the day to avoid dehydration and death. However, the desert ant, known scientifically as Cataglyphis fortis, behaves in the exact opposite manner. It emerges from its nest at midday, when the heat is at its peak, to forage for food. The central mystery that has fascinated biologists for decades is how these tiny insects can travel hundreds of meters away from their nest in a featureless desert and then return in a direct line to a hole only a few millimeters wide. [B] To solve this puzzle, researchers have studied the ant’s internal navigation system. A primary mechanism used by Cataglyphis fortis is path integration, a process often compared to "dead reckoning" in maritime navigation. The ant continuously calculates its position relative to its starting point by monitoring its direction and the distance it has traveled. While direction is determined by astronomical cues, measuring distance requires an internal odometer. In a famous experiment, a biologist named Tomas and his colleagues tested how these ants measure distance. They artificially altered the leg lengths of foraging ants by adding tiny bristles to make "stilts" or cutting them to make "stumps." Ants with stilts overestimated their distance and walked too far, while those with stumps underestimated the distance and stopped short. This demonstrated that the ants possess an internal step counter, adjusting their travel estimates based on the number of strides taken. [C] In addition to counting steps, the ants require a reliable compass to maintain their heading. The barren desert landscape provides no stable landmarks, so the ants look to the sky. Specifically, Cataglyphis fortis is sensitive to the polarization pattern of sunlight. As sunlight enters the Earth’s atmosphere, it scatters in a predictable geometric pattern that depends on the position of the sun. While this polarization is invisible to human eyes, the specialized upper section of the ant's compound eye contains photoreceptors that can detect it. Even on slightly overcast days or when the sun is high in the sky, these insects can use the polarization pattern to determine their exact orientation, ensuring they do not veer off course during their foraging runs. [D] Although path integration and sky-compass cues are highly effective, they are not completely foolproof. Small errors in step counting or direction sensing can accumulate over long distances, potentially leaving the ant lost near the end of its journey. To prevent this, Cataglyphis fortis employs backup systems when it returns to the general vicinity of its nest. As the ant gets closer to home, it shifts its reliance from path integration to localized cues. It begins searching for familiar visual features, such as specific patterns of low-lying vegetation or small pebbles. Furthermore, the ants utilize an extraordinary sense of smell. They can detect wind-borne odor cues unique to their own nest entrance. By combining these local visual and chemical cues, the ant can make precise micro-adjustments to locate its nest entrance even if its internal calculator was slightly off. [E] The evolutionary drivers behind this complex navigation system are closely linked to survival and competition. Foraging in the extreme midday heat is a high-risk activity, but it offers a substantial ecological reward. During the hottest hours, the ant's primary predators, such as desert lizards, are forced to retreat underground to regulate their body temperature. By operating during this window of safety, Cataglyphis fortis avoids the threat of predation. Additionally, the food they seek consists of the carcasses of other insects that succumbed to the heat. By being the only active foragers at midday, these ants face zero competition for these resources. The energy spent developing and maintaining such a sophisticated neurological navigation toolkit is thus offset by the exclusive access to food and safety from predators.

For generations, glaciers and ice sheets were viewed by scientists as static, solid blocks of ice frozen fast to the bedrock beneath them. It was assumed that any water generated by melting existed solely on the surface, forming transient lakes that would eventually refreeze. However, pioneering research over the last half-century has shattered this static view, revealing a highly dynamic hydrological world operating beneath hundreds of meters of solid ice. This subglacial environment features interconnected networks of lakes, rivers, and high-pressure drainage systems that not only control how fast glaciers slide toward the sea but also influence global ocean chemistry. The water that flows beneath a glacier originates from two primary sources. The first is basal melting, which occurs at the interface between the bottom of the ice sheet and the underlying rock. This process is driven by geothermal heat radiating from the Earth's core, as well as friction generated by the ice sliding over the bedrock. Although basal melting occurs continuously, it produces relatively small, steady volumes of water. The second, far more erratic source is surface meltwater. During the warm summer months, solar radiation melts the upper layers of the ice. This water accumulates in supraglacial lakes until it finds a path downward. It plunges through vertical conduits known as moulins—deep, spiral shafts carved by the rushing water itself—reaching the bed of the glacier in a matter of minutes. Once the water reaches the subglacial environment, its movement is governed by the immense weight of the overlying ice. Glaciologists categorize the resulting drainage networks into two distinct structural types: distributed and channelized systems. A distributed system consists of a sprawling network of thin water films and microscopic cavities at the ice-bed interface. Because the water in this system cannot escape quickly, it exists under extremely high pressure, often equivalent to the weight of the ice sheet itself. Conversely, a channelized system is made up of discrete, large tunnels eroded directly into the ice, known as Röthlisberger channels, or R-channels. These channels can transport massive volumes of water rapidly at low pressure, acting as the subglacial equivalent of mountain rivers. The transition between these two systems is a seasonal cycle that directly dictates glacial velocity. In early spring, as surface temperatures rise, a sudden influx of meltwater enters the subglacial zone through moulins. This volume of water easily overwhelms the slow-draining distributed system. Because the water has nowhere to go, subglacial water pressure surges. This pressure exerts an upward force on the ice, literally lifting the glacier by a few centimeters and separating it from the bedrock. With friction significantly reduced, the glacier experiences a dramatic acceleration in its seaward slide, a phenomenon known as basal sliding. As summer peaks, this high-pressure water begins to melt the surrounding ice, carving out stable R-channels. This marks the transition from a distributed to a channelized drainage system. Because these newly formed channels are highly efficient, they quickly drain the excess water, causing subglacial water pressure to drop precipitously. Consequently, the glacier settles back onto the bedrock, and its sliding velocity decreases, even though surface melting may still be at its peak. Understanding this negative feedback loop is crucial for climatologists attempting to predict how future warming will affect sea-level rise. It demonstrates that increased surface melting does not lead to a simple, linear acceleration of ice sheets, as the internal drainage network adjusts to accommodate the surplus water. Beyond their impact on ice dynamics, subglacial hydrological systems play a vital role in marine biology. As subglacial meltwater rushes along the bedrock, it crushes rocks into a fine sediment known as glacial flour. When this water eventually discharges into the ocean, it does so as a buoyant freshwater plume that rises toward the surface because fresh water is less dense than saltwater. These plumes carry high concentrations of dissolved nutrients, particularly iron and silica, which are otherwise scarce in polar waters. Dr. Tomas, a prominent polar researcher, has documented how these nutrient-bearing plumes trigger expansive blooms of phytoplankton—microscopic marine organisms that form the base of the oceanic food web. His team's field measurements in Svalbard confirmed that areas adjacent to subglacial discharge points exhibit primary productivity rates up to ten times higher than surrounding open waters. Thus, the hidden plumbing of glaciers ultimately sustains some of the most productive marine ecosystems on Earth.

【配對清單 段落】 A. Paragraph A B. Paragraph B C. Paragraph C ──────── 【標題清單 List of Headings】 i. The dual-purpose nature of early clay artifacts ii. A challenge to the linear transition model iii. How writing reinforced social divisions iv. The physical evolution from object to imprint v. The geographical spread of early bookkeeping vi. Technological limits of early recording media ──────── For generations, the invention of writing was celebrated as a sudden, almost miraculous intellectual breakthrough—a singular moment when speech was captured in permanent form. However, twentieth-century archaeological work in the Near East dismantled this romantic narrative. Excavations revealed that the cuneiform script of ancient Mesopotamia did not emerge fully formed from the mind of an unsung genius. Instead, it was the culmination of a tedious, multi-millennium evolutionary process deeply intertwined with the mundane demands of trade, agricultural management, and taxation. By tracking this evolution, we gain insight not only into how humans began to record their thoughts, but also into how early societies organized power and economic trust. [A] The foundation of this evolutionary view lies in the "token theory," championed by archaeologists such as Dr. Sofia Rossi. Rossi argued that the precursors to writing were small, three-dimensional clay counters—spheres, cones, and cylinders—that appeared in the Fertile Crescent as early as 8000 BCE. Each shape represented a specific quantity of a commodity, such as a cone for a small measure of grain or a sphere for a larger portion. For thousands of years, these tokens served as a reliable, tactile accounting system. As agricultural surpluses grew and trade networks expanded, merchants began sealing these tokens inside hollow clay envelopes, known as bullae, to prevent tampering during transit. However, this created a practical problem: once sealed, the contents of the envelope were invisible. To resolve this, accountants began pressing the tokens into the wet clay exterior of the envelope before sealing them inside, creating a physical duplicate of the contents on the surface. Eventually, scribes realized that the three-dimensional tokens inside were completely redundant. The flat, two-dimensional impressions on the outside of the clay tablet were sufficient to convey the transaction, marking the conceptual transition from physical objects to abstract symbols. [B] While Rossi’s model offers an elegant explanation for the transition from physical counting to abstract writing, it has faced criticism from scholars who argue it oversimplifies a complex historical reality. Dr. Tomas Lindqvist, for instance, points out that the transition was neither rapid nor uniform. Archaeological evidence shows that clay tokens and written clay tablets coexisted in the same administrative centers for hundreds of years. If writing were simply a superior, natural successor to tokens, the older system should have vanished quickly. Lindqvist suggests that early writing did not merely evolve to facilitate everyday merchant transactions. Instead, he argues that the earliest tablets served primarily as instruments of political centralization. Writing, in this view, was not a grassroots tool created by and for merchants; it was a top-down technology developed by elite administrators to record tribute, organize conscript labor, and enforce state control over resources. The symbols on early tablets were highly stylized and standardized, designed to be read by a select few to manage a growing state apparatus, rather than to aid commoners in daily barter. [C] This administrative exclusivity had profound social consequences, particularly in the way it restructured power within Mesopotamian city-states. The sheer complexity of early writing systems, which comprised hundreds of distinct pictographic and logographic signs, ensured that literacy remained a rare and highly guarded skill. The acquisition of these scribal skills required years of rigorous, expensive schooling in specialized institutions. The author contends that this institutional barrier was not an accidental byproduct of linguistic complexity, but rather a calculated mechanism of social stratification. By restricting access to writing, the ruling class ensured that only a select guild of scribes could interpret the law, record debts, and administer state rituals. Consequently, writing did not democratize knowledge; it consolidated authority, creating a powerful scribal bureaucracy that mediated between the ruling elite and the illiterate general populace. Although cuneiform eventually spread throughout the Near East, adapting to record diverse languages such as Akkadian, Hittite, and Hurrian, its fundamental association with state administration and elite authority persisted. Over centuries, the script became more abstract, transitioning from recognizable pictures of sheep and grain to wedge-shaped marks pressed into wet clay with a reed stylus. Yet, even as the system became more versatile, allowing for the recording of literature, epic poetry, and legal codes like the famous Code of Hammurabi, the administrative machinery of the state remained its primary patron. Today, as we conduct financial transactions using digital bank accounts and virtual currencies, we operate in an ecosystem of abstract finance that seems completely removed from ancient clay. Yet, the cognitive leap required to trust a digital ledger is fundamentally identical to the leap made by a Mesopotamian merchant trusting a marked clay tablet. In both cases, physical wealth is replaced by symbolic representation. By examining the humble origins of cuneiform, we do not merely uncover the history of the written word; we trace the very scaffolding of human trust in symbolic systems, revealing that our modern financial and social structures are built on foundations laid down in clay thousands of years ago.