Answer:
11. Something killed 90 percent of the planet's species approximately 250 million years ago, near the end of the Permian epoch. In the seas, just about 5% of animal species survived.
12. water bears, also known as tardigrades, are tough organisms that can withstand high temperatures.
13. DNA is found in every cell of every living creature, practically every cell in a multicellular organism has all of the DNA it needs.
14. Titan features a low-temperature version of Earth's water cycle, with liquid on the surface that evaporates, creates clouds, and then condenses to fall as rain—but the liquid is a mix of methane, ethane, and a trace of other hydrocarbons on Titan.
15. The Earth could not even support life at first. The atmosphere was devoid of oxygen, and the Earth's surface was scorching hot. The Earth gradually transformed over millions of years, allowing plants and animals to begin to grow. The Earth was then further altered by living organisms.
