IELTS Academic Reading Practice Test 2

A. Coral reefs, often described as the rainforests of the sea, harbour an estimated 25 percent of all marine species despite covering less than one percent of the ocean floor. These intricate ecosystems, built over millennia by tiny coral polyps that secrete calcium carbonate skeletons, provide essential services to both marine life and human communities. From coastal protection against storm surges to sustaining fisheries that feed hundreds of millions of people, the economic value of coral reefs has been estimated at $375 billion annually.

B. However, these vital ecosystems face unprecedented threats. Rising ocean temperatures, driven by climate change, trigger a phenomenon known as coral bleaching. When water temperatures exceed the normal range by as little as one to two degrees Celsius for an extended period, corals expel the symbiotic algae (zooxanthellae) living within their tissues. These algae provide corals with up to 90 percent of their energy through photosynthesis and give them their vibrant colours. Without these algae, the coral appears white or "bleached" and, unless conditions improve rapidly, will starve and die.

C. The Great Barrier Reef, the world's largest coral reef system stretching over 2,300 kilometres along Australia's northeast coast, has experienced five mass bleaching events since 2016. The most recent, occurring in 2024, was the most extensive ever recorded, with aerial surveys revealing bleaching across 73 percent of the reef. Marine biologist Professor Sarah Hughes of James Cook University notes that "the reef has virtually no time to recover between bleaching events. What used to happen once a decade is now occurring every other year."

D. Ocean acidification presents another grave threat. As the oceans absorb approximately 30 percent of atmospheric carbon dioxide, seawater chemistry changes fundamentally. The pH of surface ocean water has decreased by about 0.1 units since the pre-industrial era, representing a 26 percent increase in acidity. This makes it progressively harder for corals to build their calcium carbonate skeletons and simultaneously accelerates the dissolution of existing reef structures. Research published in the journal Nature Climate Change projects that at current emission rates, most tropical coral reefs will be exposed to conditions that prevent net growth by 2050.

E. Human activities at the local level compound these global stressors. Overfishing disrupts the delicate balance of reef ecosystems by removing herbivorous fish that control algal growth. Without these grazers, algae can overgrow and smother coral colonies. Agricultural and urban runoff introduces excessive nutrients, particularly nitrogen and phosphorus, that further fuel algal blooms while also carrying sediments that block light essential for coral photosynthesis. Destructive fishing practices, including the use of dynamite and cyanide, cause immediate physical damage to reef structures.

F. In response to this crisis, scientists and conservationists have developed innovative approaches to reef restoration. One technique involves growing coral fragments in underwater nurseries, where pieces are attached to structures like PVC "trees" and allowed to grow in optimal conditions before being transplanted back onto degraded reefs. The Coral Restoration Foundation, operating in the Florida Keys, has planted over 200,000 coral fragments since its founding, with survival rates exceeding 85 percent.

G. More controversial is the concept of "assisted evolution," where researchers selectively breed corals that demonstrate natural heat tolerance or expose corals to gradually increasing temperatures to build resilience. Scientists at the Australian Institute of Marine Science have successfully produced hybrid corals by crossing heat-sensitive species with naturally heat-tolerant varieties, creating offspring that can withstand temperatures two to three degrees above those that trigger bleaching in their parent colonies. Critics argue that such interventions could reduce genetic diversity and fail to address the root causes of reef decline.

H. Ultimately, the survival of coral reefs depends on addressing the primary driver of their decline: climate change. The Paris Agreement's target of limiting global warming to 1.5 degrees Celsius above pre-industrial levels is considered the threshold for coral reef survival. Even at 1.5 degrees of warming, an estimated 70-90 percent of existing coral reefs are projected to disappear. At 2 degrees, that figure rises to over 99 percent. The window for action is narrow, but the consequences of inaction extend far beyond the reefs themselves.

In 2008, economists Richard Thaler and legal scholar Cass Sunstein published "Nudge: Improving Decisions About Health, Wealth, and Happiness," a book that would fundamentally reshape how governments worldwide approach policy design. The central premise was deceptively simple: rather than mandating behaviour through regulation or incentivising it through financial rewards, policymakers could guide people toward better choices by subtly altering the context in which decisions are made. This approach, which Thaler and Sunstein termed "libertarian paternalism," preserves individual freedom of choice while making the desired option the path of least resistance.

The theoretical foundation of nudge theory rests on decades of research in behavioural economics and cognitive psychology, particularly the work of Daniel Kahneman and Amos Tversky on cognitive biases and heuristics. Their research demonstrated that human decision-making is systematically influenced by predictable biases: people tend to procrastinate, stick with default options, be disproportionately influenced by how choices are framed, and anchor their judgments on irrelevant reference points. Nudge theory exploits these tendencies constructively.

Perhaps the most widely cited example of a successful nudge is the automatic enrolment of employees in pension schemes. In the United Kingdom, the Workplace Pensions Reform of 2012 shifted the default from requiring employees to actively opt into pension contributions to automatically enrolling them with the option to opt out. The results were striking: participation rates among eligible employees rose from approximately 55 percent to over 90 percent. Similar programmes in the United States and New Zealand have yielded comparable outcomes, demonstrating that the power of defaults transcends cultural boundaries.

The establishment of dedicated "nudge units" within government represents the institutional embodiment of these ideas. The UK's Behavioural Insights Team (BIT), created in 2010 within the Cabinet Office, was the world's first government institution dedicated to applying behavioural science to public policy. Initially met with scepticism, the BIT quickly proved its value through rigorous randomised controlled trials. One notable project involved redesigning tax reminder letters to include the statement "9 out of 10 people in your area pay their tax on time." This simple addition of social norms information increased timely tax payments by several percentage points, generating millions in additional revenue at virtually no cost.

In the health domain, nudges have shown particular promise. Rearranging cafeteria layouts to place healthier options at eye level and at the beginning of serving lines has consistently increased the selection of fruits and vegetables by 25 to 35 percent across multiple studies. Graphic warning labels on cigarette packages, while more forceful than a typical nudge, combine visceral emotional impact with informational content to discourage smoking initiation. Default settings in electronic health records that prompt doctors to prescribe generic rather than branded medications have reduced prescription costs without affecting patient outcomes.

However, nudge theory has attracted significant criticism from multiple directions. Ethical concerns centre on the manipulation of choice architecture, with critics arguing that nudges bypass rational deliberation and undermine genuine autonomy. Philosopher Luc Bovens has argued that nudges that exploit cognitive biases to achieve policy objectives treat citizens as means rather than ends, violating Kantian principles of respect for persons. The question of who decides what constitutes a "better" choice for individuals remains fundamentally unresolved.

A more practical criticism concerns the limitations of nudges as a policy tool. While effective for simple, one-time decisions like pension enrolment, nudges may be insufficient for addressing complex, ongoing behavioural challenges such as obesity, addiction, or climate change. Behavioural scientist George Loewenstein has warned against "nudge-ism" becoming a substitute for structural reforms, arguing that nudges can give policymakers the illusion of action while avoiding the more difficult and politically costly interventions that systemic problems require.

Despite these critiques, the influence of behavioural insights in government continues to expand. As of 2025, over 200 public institutions worldwide have adopted behavioural science units, and the approach has been integrated into the policy frameworks of organisations including the World Bank, the European Commission, and the United Nations. The challenge moving forward lies in maintaining rigorous evaluation standards, ensuring transparency about when and how nudges are deployed, and recognising both the power and the limitations of this approach to improving human welfare.

The human brain's capacity for language has long fascinated scientists, but the neurological effects of speaking multiple languages have only recently become a focus of sustained research. Advances in neuroimaging technology, particularly functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), have enabled researchers to observe the bilingual brain in action, revealing structural and functional differences that challenge earlier assumptions about how language is processed and stored.

One of the most significant findings is that bilingual individuals do not simply "switch off" one language when using the other. Instead, both languages remain active simultaneously, creating a state of constant competition that the brain must manage. This has been termed "parallel activation," and it requires the executive control system to continuously select the appropriate language while inhibiting the other. The prefrontal cortex, anterior cingulate cortex, and basal ganglia all play roles in this language management process.

This constant cognitive exercise appears to strengthen the brain in measurable ways. A landmark 2004 study by Ellen Bialystok at York University demonstrated that bilingual individuals outperform monolinguals on tasks requiring executive function, including attention control, cognitive flexibility, and the ability to ignore irrelevant information. The "bilingual advantage" in executive function has since been replicated in studies involving children, young adults, and older adults, though the size of the advantage and the specific tasks on which it manifests remain subjects of ongoing debate.

Structural brain imaging studies have revealed that bilingualism is associated with increased grey matter density in several brain regions, most notably the left inferior parietal lobule, which is involved in language processing and vocabulary storage. Research by Andrea Mechelli and colleagues at University College London found that this increase in grey matter density was correlated with the age at which the second language was acquired and the proficiency level attained, suggesting that the neural changes are experience-dependent rather than innate.

Perhaps the most provocative finding concerns the relationship between bilingualism and cognitive decline. Multiple large-scale epidemiological studies have found that bilingual individuals develop symptoms of Alzheimer's disease and other forms of dementia an average of four to five years later than comparable monolingual individuals. Crucially, this delay occurs despite bilingual brains showing equivalent levels of physical pathology, suggesting that bilingualism builds a "cognitive reserve" that allows the brain to function normally for longer even as disease progresses.

The concept of cognitive reserve proposes that a lifetime of managing two language systems creates neural networks that are more efficient and adaptable. When disease begins to damage certain pathways, the bilingual brain can recruit alternative networks to compensate. This mirrors findings from studies on other forms of cognitive enrichment, such as education and occupational complexity, but the bilingual advantage appears to operate through distinct mechanisms related specifically to the demands of language management.

However, the "bilingual advantage" hypothesis has not gone unchallenged. A comprehensive meta-analysis published in 2023 by Kenneth Paap and colleagues examined 170 studies and found that the evidence for cognitive advantages was inconsistent, with publication bias potentially inflating positive results. Studies conducted in bilingual communities where multilingualism is the norm, such as India and parts of Africa, often fail to replicate the advantages found in studies of bilinguals in predominantly monolingual societies, suggesting that the advantage may be related to the social or cognitive demands of managing language use in a monolingual-dominant environment rather than bilingualism per se.

The question of what counts as "bilingual" further complicates the research. The spectrum ranges from individuals who acquired two languages from birth (simultaneous bilinguals) to those who learned a second language in adulthood (sequential bilinguals), from those who use both languages daily to those who rarely use their second language. Different types of bilingual experience may produce different neurological effects, making broad generalisations problematic.

Despite these complexities, the field continues to advance. Recent research using diffusion tensor imaging (DTI) has revealed that bilingualism is associated with enhanced white matter integrity, particularly in the corpus callosum, the structure connecting the brain's two hemispheres. This finding suggests that bilingualism may improve communication between brain regions, not just within specific language areas. As neuroimaging techniques become more sophisticated and sample sizes increase, a more nuanced understanding of how multilingualism shapes the brain is likely to emerge.