영어 모의고사 (자동 편성)

A plastic bag that fully decomposes within months rather than lingering for centuries sounds almost too convenient to be real, yet certain bioplastics on the market ①do exactly that under the right conditions. Unlike conventional plastic, derived almost entirely from petroleum, many bioplastics are ②synthesized from renewable feedstocks such as corn starch or sugarcane, sometimes with the help of bacteria engineered to produce plastic-like polymers as a byproduct of their metabolism. Not every bioplastic biodegrades quickly, however, and some marketed as eco-friendly break down only in industrial composting facilities ③that reach conditions rarely found in a backyard compost heap or the open ocean. Critics point out that growing crops for bioplastic production can compete with food crops for farmland and water, ④complicating the assumption that a biological origin automatically makes a material more sustainable. Researchers are now exploring bioplastics made from agricultural waste and algae instead of dedicated crops, hoping to ⑤sidestepping this competition for land while preserving the benefits that first made bioplastics appealing.

A single fertilized egg eventually gives rise to every cell type in the human body, from neurons to bone, a feat that has ①fascinated biologists for more than a century. Embryonic stem cells retain much of that original ②versatility, capable in principle of developing into almost any tissue, which is why researchers have long viewed them as a promising raw material for repairing damaged organs. Because harvesting these cells traditionally required destroying a human embryo, the research ③eliminated ethical objections fierce enough to slow funding and legislation in several countries for years. A breakthrough arrived when scientists discovered that ordinary adult skin cells could be reprogrammed into a state resembling embryonic versatility without ever touching an embryo. These induced pluripotent cells have not entirely erased the ethical debate, but they have opened a path for stem cell research that far more scientists and funding agencies are ④willing to ⑤support.

Imagine rewriting a bacterium's code the way a programmer edits a line of software, and much of what synthetic biology ①promises begins to make sense. Researchers in this field assemble standardized genetic parts into circuits that can be inserted into a cell, instructing it to perform a task that no natural organism would ②carry out. Because these circuits are built from interchangeable parts rather than designed from scratch each time, a circuit tested in one lab can often be reused, with ③minor adjustments, in an entirely different application. Critics note that biological systems ④always behave as predictably as electronic circuits, since a gene inserted into a new cell can interact with existing pathways in unexpected ways, occasionally producing results no engineer intended. Even so, as the catalog of standardized parts keeps expanding, engineers are gaining ⑤confidence to design increasingly complex systems.

A liver no longer has to sit inside a human body to be studied closely. By coaxing stem cells to organize themselves within a nutrient-rich gel, scientists can now grow miniature three-dimensional structures called organoids, which reproduce much of the architecture and function of a real organ. Unlike flat cultures grown on a plastic dish, organoids let cells interact in three dimensions much as they would inside the body, yielding tissue that behaves in strikingly realistic ways. This fidelity has made organoids invaluable for testing how a drug affects human tissue before any patient is exposed, _______________. Some laboratories have even grown organoids from a single patient's own cells, raising the possibility of trialing a treatment on a miniature copy of that patient's organ before committing to an actual course of therapy.

Bacteria have been cutting up invading viral DNA for billions of years, long before any scientist thought to borrow the trick for use in a laboratory. The CRISPR-Cas9 system relies on a short guide RNA that matches a specific DNA sequence, _______________. Once Cas9 arrives at the target site, it slices both strands of the DNA helix, and the cell's own repair machinery rushes in to mend the cut, often introducing a small change in the process. By supplying the cell with a template during this repair step, scientists can direct that machinery to insert a specific new sequence rather than merely disabling the original gene. What once required years of painstaking work to alter a single gene can now be accomplished within days.

Imagine a brilliant scientist named Mary who has spent her entire life inside a black-and-white room, learning everything physical science could ever teach about color. (A) Despite this complete physical knowledge, Mary herself has never actually seen a color, since every book, screen, and object in her world has been carefully restricted to shades of gray. (B) Suppose that one day Mary is finally released from the room and shown a ripe red tomato for the first time. (C) Philosopher Frank Jackson argued that Mary would learn something entirely new at that moment, namely what it actually feels like to see red, even though she already possessed every physical fact about color.

The human gut hosts trillions of microorganisms whose combined genetic material outnumbers that of the human genome itself many times over. (A) A microbiome disrupted by antibiotics, poor diet, or chronic stress can leave the gut lining more permeable than it should be, allowing substances to leak into the bloodstream that would normally stay contained. (B) Once dismissed as passive hitchhikers, these bacteria are now understood to actively shape digestion, regulate immune responses, and even influence the production of chemicals that affect mood and behavior. (C) Researchers studying this connection have found that transplanting gut bacteria from a healthy donor into a patient can relieve symptoms of certain digestive disorders, though the microbiome varies enormously between individuals, so a treatment that helps one person's gut may do little for someone else's.

For patients born with a single faulty gene, the disease has traditionally been treated indirectly, managing symptoms for a lifetime rather than addressing the genetic error itself. (A) Early trials were haunted by serious setbacks, including cases in which the delivery virus triggered a dangerous immune reaction, but refined delivery methods have since made the treatment considerably safer, leading regulators in several countries to approve gene therapies for a small but growing number of rare inherited disorders. (B) Gene therapy attempts something more ambitious: delivering a corrected copy of the gene directly into a patient's cells, often using a disabled virus stripped of its ability to cause illness as a delivery vehicle. (C) Once inside the nucleus, the corrected gene can begin producing the protein the patient's body had always lacked, in some cases reversing symptoms that medication alone had never been able to touch.

Left undisturbed for several days, this arrangement of fibers slowly takes on the texture that consumers associate with real meat. A hamburger patty need not come from a slaughtered animal at all if a small sample of muscle cells can be persuaded to multiply inside a steel tank. ( ① ) Cultured meat begins with a biopsy of animal muscle tissue, from which scientists isolate cells capable of dividing repeatedly, then feed those cells a nutrient broth that supplies the sugars, proteins, and minerals an animal's bloodstream would normally provide. ( ② ) Inside a bioreactor, the cells multiply across scaffolding designed to encourage them to align into fibers. ( ③ ) This gradual process thickens the tissue into something that begins to resemble muscle rather than a shapeless clump of cells. ( ④ ) Supporters argue that because the process never requires raising and slaughtering a whole animal, it could shrink the land, water, and greenhouse gas emissions associated with conventional meat production. ( ⑤ ) Skeptics counter that producing the specialized broth at a large enough scale remains prohibitively expensive, meaning cultured meat is unlikely to compete with conventional meat in price until the technology matures considerably further.

That trajectory has continued to accelerate ever since, each new generation of vaccine technology arriving faster than the one before it. When a country physician named Edward Jenner noticed that milkmaids who had caught cowpox seemed immune to smallpox, he set in motion a medical revolution without fully understanding why it worked. ( ① ) For nearly two centuries afterward, vaccine development proceeded largely by trial and error, weakening or killing a pathogen and testing whether the resulting preparation could train the immune system without causing disease itself. ( ② ) This method produced genuine successes, eventually eliminating smallpox worldwide and reducing diseases such as polio and measles. ( ③ ) Each new vaccine, however, still required years of laboratory work with no guarantee of success. ( ④ ) Advances in molecular biology eventually allowed researchers to isolate a single protein from a pathogen's surface rather than using the whole organism, producing vaccines with fewer side effects and a more predictable safety profile. ( ⑤ ) The most recent shift, toward delivering genetic instructions rather than proteins themselves, represents the latest chapter in a story that began with an eighteenth-century doctor's curiosity about a puzzling immunity among dairy workers.