UCLA ASTRO 5 FINAL EXAM ACTUAL 2025/2026 QUESTIONS AND 100% CORRECT ANSWERS

UCLA ASTRO 5 FINAL EXAM ACTUAL 2025/2026 QUESTIONS AND 100% CORRECT ANSWERS What formed the Sun and planets? - Answer -Cloud of gas & dust Why is the Solar System flat? - Answer -Rotational forces in combination with gravitational forces What is the habitable zone? What defines it? - Answer -The habitable zone of the solar system is where the temperature is right to be able to support life - not too close to the sun, not too far away. The frost line defines the habitable zone. Why are the inner planets rocky, while the outer planets are gaseous? - Answer -The frost line. The outer planets were formed first, and formed outside the frost line, so they had more vitreous materials to create their planets from, and hydrogen ice. The inner planets had less materials to work with and were formed inside the frost line with hydrogen vapor. How was the moon formed? How do we know that? - Answer -Moon was formed when a competing planet crashed into the Earth during its formation, then got caught in our orbit. We know this because Earth is the only rocky planet with a large moon and the materials on the surface of the moon are the same as on Earth.What was the Late Heavy Bombardment? Why was it both a good and bad thing for life on Earth? - Answer -~4 BYA, period of intense asteroid and comets in the Solar System. Wiped out any life Earth may have had at that time, but brought water, nitrogen atmosphere, and possibly life. When did life on Earth begin? What evidence to scientists use to determine this? - Answer -~3.8 BYA. Microfossils (fossils of anaerobic bacteria before rise of oxygen, ~3.4 BYA), Stromatolites (colony of microbes that used photosynthesis ~3.5 BYA), Zircon Crystals (Not direct evidence, but since need water could show life ~4.5 BYA) Why does it matter exactly when Earth began? - Answer -Then we can make determinations and more educated guesses about how life on Earth began - whether it was created organically here, whether ingredients were brought here, or whether life itself was delivered here. What was the Miller-Urey experiment? What did we learn from it? - Answer -Miller-Urey experiment was an experiment done to see if molecules could form organically from scratch in Earth's atmosphere. Although experiment wasn't perfect, through repeated trials we learned that it could. How did the first strands of RNA form? - Answer -Ingredients came together in the mud of shallow ponds to form RNA.The bases stick to the mud/clay and then find each other to form strands. How did the first cells form? - Answer -The RNA strands were trapped in a pre-cell/vesicle and go through evolution of self replication. From here, DNA evolves from RNA to form a true cell.