Text Organization Patterns Practice Test

Earth's orbit has become increasingly cluttered with debris, a problem known as "space junk." This material, ranging from defunct satellites to tiny flecks of paint, travels at incredible speeds and poses a serious threat to active satellites and future space missions. Addressing this challenge has spurred considerable innovation. One proposed solution is a "space harpoon," a craft that would spear larger pieces of debris and drag them into a lower orbit to burn up in the atmosphere. Another concept involves using powerful ground-based lasers to gently nudge debris into new, less hazardous orbits. More ambitiously, some engineers are designing nets and robotic arms that could capture multiple pieces of junk at once. Each of these ideas faces immense technical and financial hurdles, but the growing danger makes finding a workable solution increasingly urgent.

The Great Barrier Reef is not a single, continuous wall but a vast and intricate mosaic of over 2,900 individual reefs and 900 islands stretching for over 2,300 kilometers. Its complexity is staggering. The outer reefs, facing the open ocean, are battered by waves and are home to the most robust and fast-growing corals. In the calmer waters behind this protective barrier lie the inner, or lagoonal, reefs. These areas feature more delicate coral formations and are often dotted with seagrass beds that serve as nurseries for countless marine species. The reef's vibrant colors come from tiny algae called zooxanthellae living within the coral polyps. This ecosystem is a hub of biodiversity, supporting thousands of species of fish, mollusks, sea turtles, and marine mammals, making it one of the most complex natural structures on Earth.