Selective High School Placement Test — VIP Practice Exam

Read the following passage, then answer Questions 1–6. --- The ocean covers more than 70 percent of Earth's surface and contains approximately 97 percent of the planet's water. Despite its vastness, scientists estimate that less than 20 percent of the world's oceans have been mapped in high resolution. The deep ocean — regions below 200 metres — remains one of the most unexplored environments on Earth. In 2012, filmmaker and explorer James Cameron descended to the Mariana Trench, the deepest point in the ocean at approximately 11 kilometres below sea level. His submersible, the Deepsea Challenger, was specially engineered to withstand pressures over 1,000 times greater than at sea level. During his descent, Cameron collected scientific samples and filmed creatures never before observed by humans. The challenges of deep-sea exploration are immense. Pressure increases by one atmosphere for every 10 metres of depth, meaning equipment must be extraordinarily robust. Light does not penetrate below 1,000 metres, creating a zone of perpetual darkness where bioluminescent organisms produce their own light. Temperatures near the ocean floor can drop to near freezing, even in tropical regions. Despite these challenges, the deep ocean supports thriving ecosystems. Hydrothermal vents — cracks in the ocean floor where superheated water emerges — host communities of organisms that survive without sunlight, drawing energy from chemical reactions instead of photosynthesis. These discoveries have expanded our understanding of where life can exist, with implications for the search for life on other planets. --- According to the passage, what proportion of the world's oceans have been mapped in high resolution?

Questions 2–30 and full explanations are VIP-exclusive.