Four requirements for the current chemical evolution model were likely met in the early EarthĪbundant energy sources (volcanism, thunderstorms, and bombardment with particles and radiation from space were all

Small amounts of NH 3, H 2 S, and CH 4 – note the lack of O 2, which is a major constituent of today’s atmosphereĬ. Earth’s early atmosphere (when life first appears in the fossil record) most likely consisted of CO 2, H 2 O, CO, H 2, N 2, and Some models go out to 6 billion years, it is hard make a rule for a definitive starting point of planet formationī.  oldest known meteorites (4 bya for the age of the solar system)  oldest known Earth minerals (date to 4 billion years ago, or 4 bya) the Earth is about 4 billion years old (time of the first likely solid surface)

Chemical conditions of the early Earth that could have fostered the origin of lifeĪ. What is the sixth extinction?Ĭhapter 25 : The Origin and Evolutionary History of Life on Earth Outline the relative history, dominant organisms, and key events of each of the periods of the Paleozoic, Mesozoic, and Cenozoic eras. For each of the “big five” mass extinctions, give when they occurred, their likely causes if known, and key consequences of them. When was Precambrian time and what were the major events during that time period? 13. When do eukaryotic cells appear in the fossil record? 12. When did oxygenation of Earth’s atmosphere occur, and what were the key consequences of it? 11. What are banded iron formations, and why are they important? 10. What are microfossils, and to what age to the oldest ones found on Earth date? 8. Explain the RNA world hypothesis and how in vitro evolution tests it. What are protobionts and microspheres, and what does their existence imply about how cellular life began? 6. Briefly discuss at least three different models for how life began on Earth. Describe the contributions of Oparin and Haldane and of Miller and Urey to models of the origin of life on Earth. What are considered to be the four requirements for life to begin on Earth? 3. What is the best current estimate of the age of the Earth, and what is the evidence for that estimate? 2. Chapter 25: The Origin and Evolutionary History of Life on Earth 1.

Modern bio study guide answers 25-1