The central dogma of biology validates the importance of the Miller-Urey experiment: DNA transcribes into RNA, which translates into amino acids, which combine to form proteins, the building blocks of life.
The growth of the human population is threatening other species. Some endangered animals include: African and Asian elephants, West Indian manatees, American alligators, Western gorillas, grizzly bears, Florida cougars, jaguars, tigers, black rhinos, humpback whales, sperm whales, green sea turtles, Atlantic salmon, and red wolves.
Imagine a population of mice living in a dark forest. Would the light ones or the dark ones be more likely to not be eaten by predators? Over time, which color of mice would you expect to see more often?
Carbon, hydrogen, oxygen, nitrogen, phosphorus, and calcium are the most important materials for life. Although there is plenty of it, we cannot simply absorb nitrogen gas. Think about how organisms might get nitrogen.
Think of climbing stairs, the higher you climb the less energy you have, so animals on the top of the pyramid only have a fraction of the energy that animals near the bottom of the pyramid do.