Đề thi thử số 9 — Reading 40 câu

The debate between organic farming and conventional agriculture has intensified in recent years as consumers, scientists, and policymakers grapple with questions about food safety, environmental sustainability, and global food security. Organic farming, broadly defined, is a method of agricultural production that avoids the use of synthetic pesticides, chemical fertilizers, genetically modified organisms, and growth hormones. Instead, organic farmers rely on natural processes such as crop rotation, composting, biological pest control, and the use of organic fertilizers derived from animal and plant waste.

Proponents of organic farming argue that it offers significant environmental benefits. By eliminating synthetic chemicals, organic practices reduce soil and water contamination, protect pollinators such as bees and butterflies, and promote greater biodiversity on farmland. Studies have shown that organic farms tend to have 30 percent more species diversity than conventional ones. Furthermore, organic farming methods can improve soil health over time by increasing organic matter content, enhancing water retention, and fostering beneficial microbial communities. Healthy soil, in turn, can sequester more carbon, potentially contributing to climate change mitigation.

However, critics of organic farming point to several important limitations. The most frequently cited concern is lower crop yields. On average, organic farms produce 20 to 25 percent less food per hectare than conventional farms, a significant gap when the world must feed a population expected to reach nearly 10 billion by 2050. This yield gap means that organic farming would require substantially more land to produce the same amount of food, potentially leading to further deforestation and habitat loss. Additionally, organic food products typically cost more than their conventional counterparts, making them less accessible to low-income families.

Conventional agriculture, by contrast, has been remarkably successful at increasing food production over the past century. The Green Revolution of the 1960s and 1970s introduced high-yield crop varieties, synthetic fertilizers, and modern irrigation techniques that dramatically boosted output and helped avert famine in parts of Asia and Latin America. However, this productivity has come at a cost. Intensive use of chemical inputs has degraded soil quality in many regions, contaminated waterways with nutrient runoff that creates oxygen-depleted "dead zones," and contributed to the decline of insect populations essential for crop pollination.

Many agricultural scientists now advocate for a middle path that integrates the strengths of both approaches. Integrated pest management, for example, combines biological controls with minimal and targeted use of chemicals to reduce environmental harm without sacrificing yields entirely. Precision agriculture uses technology such as GPS and sensors to apply inputs only where and when they are needed, minimizing waste. These hybrid strategies suggest that the future of food production may not require choosing between organic and conventional methods, but rather combining the best elements of each to create a sustainable, productive, and equitable food system for the coming decades.

The concept of remote work is not new. As early as the 1970s, the term "telecommuting" was coined by Jack Nilles, a NASA engineer who envisioned a future in which technology would allow employees to work from home instead of commuting to centralized offices. However, for decades, remote work remained a niche arrangement available primarily to freelancers, consultants, and a small number of technology workers. The vast majority of employees continued to report to traditional offices, and many employers remained skeptical about whether workers could be productive outside of a supervised workplace environment.

The global COVID-19 pandemic, which began in early 2020, fundamentally transformed this landscape. Lockdowns and social distancing measures forced millions of companies worldwide to adopt remote work virtually overnight. What had been a gradual trend suddenly became an urgent necessity. Organizations that had never considered remote work discovered that, with the right technology and management practices, employees could perform their jobs effectively from home. Surveys conducted during the pandemic consistently showed that the majority of remote workers reported equal or higher productivity compared to working in an office, challenging longstanding assumptions about the need for physical presence.

The benefits of remote work extend beyond productivity. Employees frequently cite improved work-life balance as a primary advantage, as eliminating daily commutes can save hours each week that can be redirected toward family, exercise, or personal interests. For employers, remote work can reduce overhead costs associated with maintaining large office spaces, including rent, utilities, and office supplies. Companies also gain access to a broader talent pool, as geographical limitations on hiring are diminished when employees can work from anywhere. This is particularly significant for organizations in high-cost urban centers, which can recruit skilled workers from regions with lower costs of living.

Nevertheless, the shift to remote work has not been without significant challenges. Many workers report feelings of isolation and loneliness, particularly those who live alone or are naturally extroverted. The blurring of boundaries between work and personal life can lead to burnout, as employees find it difficult to "switch off" when their home doubles as their office. Managers face difficulties in maintaining team cohesion, fostering spontaneous collaboration, and assessing performance when they cannot observe employees directly. Furthermore, remote work exacerbates existing inequalities, as it is primarily available to white-collar knowledge workers, while millions of people in manufacturing, retail, healthcare, and service industries cannot perform their jobs remotely.

As the world moves beyond the pandemic, a consensus is emerging that the future of work will be hybrid rather than fully remote or fully in-person. Most major companies have adopted policies that allow employees to split their time between home and the office, typically requiring two to three days of in-person attendance per week. This hybrid model attempts to capture the flexibility and efficiency benefits of remote work while preserving the social interaction, mentorship opportunities, and cultural cohesion that come from working together in a shared physical space. The challenge for organizations going forward will be designing hybrid work environments that are equitable, inclusive, and genuinely effective for all employees.

Ocean acidification, often called "the other carbon dioxide problem," is a process by which the world's oceans are becoming increasingly acidic due to their absorption of excess carbon dioxide from the atmosphere. Since the beginning of the Industrial Revolution, the oceans have absorbed roughly 30 percent of the carbon dioxide produced by human activities, including the burning of fossil fuels, deforestation, and cement production. While this absorption has helped slow the rate of global warming by reducing the amount of CO2 in the atmosphere, it has come at a considerable cost to marine ecosystems.

When carbon dioxide dissolves in seawater, it undergoes a series of chemical reactions that produce carbonic acid. This acid then releases hydrogen ions, which lower the pH of the water, making it more acidic. Since pre-industrial times, ocean surface pH has dropped by approximately 0.1 units, from about 8.2 to 8.1. While this may seem like a small change, pH is measured on a logarithmic scale, meaning that this shift represents a roughly 26 percent increase in hydrogen ion concentration. Scientists project that if carbon emissions continue at current rates, ocean pH could decline by an additional 0.3 to 0.4 units by the end of the century, with profound consequences for marine life.

The organisms most immediately threatened by ocean acidification are those that build shells or skeletons from calcium carbonate, including corals, mollusks, sea urchins, and certain species of plankton known as coccolithophores. As the ocean becomes more acidic, the concentration of carbonate ions decreases, making it harder for these organisms to form and maintain their protective structures. Coral reefs, which support approximately 25 percent of all marine species despite covering less than one percent of the ocean floor, are particularly vulnerable. Research indicates that many coral species will struggle to build reefs at the rate of acidification projected for 2050, potentially leading to the collapse of reef ecosystems that millions of people depend on for food, coastal protection, and livelihoods.

The effects of ocean acidification ripple through entire food chains. Pteropods, tiny sea snails sometimes called "sea butterflies," are a foundational food source for salmon, mackerel, herring, and many whale species. Laboratory studies have shown that the shells of pteropods begin to dissolve within 48 hours when exposed to the pH levels expected by 2100. If pteropod populations decline significantly, the consequences could cascade upward through the food web, affecting commercially important fish stocks and the communities that depend on them. Beyond calcifying organisms, acidification can also impair the sensory abilities of fish, making it harder for them to detect predators, find food, and navigate to suitable habitats.

Addressing ocean acidification requires tackling its root cause: the reduction of carbon dioxide emissions. International agreements such as the Paris Climate Accord aim to limit global temperature increases, which would simultaneously slow the rate of ocean acidification. At the local level, strategies such as reducing agricultural runoff, which contributes to coastal acidification, and establishing marine protected areas can help build resilience in vulnerable ecosystems. Some researchers are also exploring more experimental approaches, including ocean alkalinity enhancement, which involves adding minerals to seawater to neutralize excess acidity. However, most scientists agree that the most effective long-term solution is a rapid and sustained reduction in humanity's carbon footprint.

Animal testing, also known as animal experimentation, refers to the use of non-human animals in scientific research, product development, and medical testing. The practice dates back to ancient Greece, where philosophers such as Aristotle and Erasistratus performed experiments on living animals to understand anatomy and physiology. Today, an estimated 100 million animals are used in laboratories worldwide each year, including mice, rats, rabbits, dogs, primates, and fish. These animals are used to test the safety of pharmaceuticals, vaccines, cosmetics, and household chemicals, as well as to advance basic scientific understanding of diseases and biological processes.

Supporters of animal testing argue that it has been instrumental in virtually every major medical advancement of the past century. The development of antibiotics, insulin, organ transplant techniques, and vaccines for diseases such as polio, tuberculosis, and COVID-19 all relied on animal testing at critical stages. Proponents contend that because the biological systems of animals, particularly mammals, share significant similarities with those of humans, testing on animals remains the most reliable way to predict how treatments will affect human patients before clinical trials begin. Without animal testing, they argue, the development of new medicines would be slower, riskier, and potentially more dangerous for human volunteers.

Opponents of animal testing raise both ethical and scientific objections. From an ethical standpoint, they argue that animals are sentient beings capable of experiencing pain, fear, and distress, and that subjecting them to invasive procedures, toxic substances, and prolonged confinement constitutes a form of cruelty that cannot be justified regardless of the potential benefits to humans. The philosopher Peter Singer, whose 1975 book "Animal Liberation" helped launch the modern animal rights movement, coined the term "speciesism" to describe the moral prejudice that leads humans to prioritize their own interests over those of other species, drawing parallels with racism and sexism.

From a scientific perspective, critics note that animal models do not always accurately predict human responses. Studies have shown that approximately 95 percent of drugs that pass animal testing fail in human clinical trials, either because they prove ineffective or produce unacceptable side effects. This high failure rate suggests that the physiological differences between species can render animal tests misleading, raising questions about whether the suffering inflicted on laboratory animals is truly necessary. Advances in technology have produced increasingly sophisticated alternatives, including organ-on-a-chip devices that simulate human organ functions, three-dimensional tissue models grown from human cells, and computational models that can predict drug interactions based on vast datasets of existing research.

The regulatory landscape reflects the complexity of this debate. The European Union banned animal testing for cosmetics in 2013, a decision that has been adopted or emulated by several other jurisdictions including India, Israel, and parts of Australia. However, most countries continue to require animal testing for pharmaceutical products before they can be approved for human use. In the United States, the FDA Modernization Act of 2022 removed the longstanding requirement that drugs must be tested on animals before human trials, opening the door for alternative methods. Most ethicists and scientists agree that the goal should be the progressive replacement of animal testing with reliable alternatives, guided by the principle of the "Three Rs": Replacement of animals with alternative methods where possible, Reduction of the number of animals used, and Refinement of procedures to minimize pain and distress.