Chapter 25: The History of Life on Earth
Order by
20 terms
Terms | Definitions |
|---|---|
 What is the sequence of stages thought to have allowed the earliest cells to form? | 1. abiotic synthesis of small organic molecules 2. Polymerization of these molecules 3. Packaging into "protobiotns" 4. Rise of self-replicating molecules that allowed inheritance |
| How old is the earth according to scientific evidence? | 4.6 billion years |
| How are the earliest organic molecules thought to have formed? | contained water vapor and many chemicals released by volcanic eruptions; nitrogen, nitrogen oxides, carbon dioxide, methane, ammonia, hydrogen, hydrogen sulfide |
| Can these molecules spontaneously polymerize? | small organic molecules polymerize when they are concentrated on hot sand, clay or rock; replication and metabolism are key properties of life |
| Protocells | are aggregates of abiotically produced molecules surrounded by a membrane or membrane-like structure; first genetic material was probably RNA, ribosymes have been found to catalyze many different reactions |
| Fossil record | mostly from sedimentary rocks; information on evolution over billions of years |
| How are rocks and fossils dated? | sedimentary strata; absolute ages of fossils are determined through radiometric dating; each isotope has a half-life, the time required for half the parent isotope to decay (parent->daughter isotope) |
| When did the earliest prokaryotes appear? | stromatolites; rocklike structures made of layers of bacteria and sediment; 3.5 billion years ago (only prokaryotes on earth: 3.5-2.1 billion years) |
| What did the earliest prokaryotes contribute? | ... |
| When did oxygen start to accumulate? | oxygenic photosynthesis: 2.7-2.3 billion years ago |
| How old are eukaryotic cells? | oldest fossils: 2.1 billion years |
| How are eukaryotic thought to have arisen? | endosymbiosis: proposes that mitochondria and plastids were formerly small prokaryotes living within larger host cells (explains diversity in algal groups); evidence includes: similarities in inner membrane structure and function, both have their own circular DNA |
| What is a chimera? | Greek mythology: part lion, part goat, part serpent; joining together of parts of organisms into one; applied to endosymbiosis |
| What is the scientific explanation for the origins of multicellularity? | multicellular organisms evolved about 1.2 billion years ago; the first multicellular organisms were colonies of autonomously replicating cells |
| Continental drift | earth's continents are not fixed, they drift on great plates, often the plates side along other plates (pulling and pushing), important geological processes occur at boundaries |
| "Cambrain Explosion" | many animal phyla diverged at 1billion-700million years ago; major phyla of animals appeared at the first 20million years of the Cambrian period |
| Pangaea | supercontinent; late Paleozoic era, breakup during mesozoic era, explains similarity of fossils in South America and Africa |
| Mass extinction events | 5 mass extinction events; more than 50% of earth's species became extinct; sixth human-caused mass extinction is likely to occur |
| What is adaptive radiation? | is the evolution of diversity adapted to species from a common ancestor upon introduction to new environmental opportunities |
| How did this phenomenon contribute to the flora and fauna of the Hawaiian Islands? | species are very closely related to each other (Ie. silversword alliance) but are different in appearance/characteristic due to the various environments of the islands |
First Time Here?
Welcome to Quizlet, a fun, free place to study. Try these flashcards, find others to study, or make your own.