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Actual Planets 2 Mid
Actual Planets 2 Midterm
| Question | Answer |
|---|---|
| When did life arise on Earth? | Life probably arose on Earth more than 3.85 billion years ago. |
| What evidence supports the early existence of life on Earth? | Evidence comes from fossils and carbon isotopes. |
| What are the two types of dating used to determine the age of fossils? | Relative ages (deeper layers formed earlier) and absolute ages (radiometric dating). |
| What do the rock layers of the Grand Canyon record? | 500 million years of Earth's history. |
| What is the significance of the oldest fossils? | They show that bacteria-like organisms were present over 3.5 billion years ago. |
| What are stromatolites? | Colonies of microbes that are considered some of the earliest life forms. |
| What is the Geological Time Scale? | A system that describes the timing and relationships of events in Earth's history. |
| What does the theory of evolution suggest about life on Earth? | Life evolves through time and all life shares a common ancestry. |
| What mechanism did Darwin propose for evolution? | Natural selection. |
| What role does DNA play in evolution? | Evolution proceeds through mutations in DNA. |
| What does the 'Tree of Life' represent? | Genetic relationships among all living organisms, suggesting characteristics of common ancestors. |
| Where might the earliest life forms have thrived on Earth? | Near deep ocean volcanic vents. |
| What did the Miller-Urey experiment demonstrate? | The building blocks of life can form easily under early Earth conditions. |
| What are amino acids? | Simple structures that are the building blocks of proteins. |
| How many different amino acids are used in all living things? | Only 22 amino acids. |
| What are proteins made of? | Folded chains of amino acids. |
| What are 'pre-cells'? | Microscopic, enclosed membranes created in the lab that mimic early life forms. |
| Could life have migrated to Earth? | Yes, Earth and Mars have exchanged rocks, and some organisms can survive in space. |
| What significant event occurred 3.5 billion years ago? | Cyanobacteria started releasing oxygen. |
| What was the Cambrian Explosion? | A period approximately 540-500 million years ago marked by a rapid increase in the diversity of life. |
| What is the significance of the time period 225-65 million years ago? | Dinosaurs and small mammals thrived during this time. |
| What are some challenges in understanding the origin of life? | Laboratory experiments are limited in time compared to the long evolutionary process. |
| What is the purpose of the Student Experience of Teaching Surveys? | To provide feedback on teaching quality and improve the course. |
| What are the BIG questions addressed in the study of life in the universe? | How did life start on Earth and is there life anywhere else? |
| What are the requirements for surface habitability on extrasolar planets? | Conditions that allow for the presence of liquid water and other life-supporting elements. |
| What does SETI stand for? | Search for Extra-Terrestrial Intelligence. |
| What is the primary source of oxygen in Earth's atmosphere? | Cyanobacteria, which release oxygen via photosynthesis. |
| When did oxygen begin to build up in Earth's atmosphere? | Around 2 billion years ago. |
| What are the three necessities for life? | Nutrient source, energy, and liquid water. |
| How long ago did life arise on Earth? | At least 3.85 billion years ago. |
| What is the significance of the Perseverance rover's mission on Mars? | It is analyzing rocks and caching samples for return to Earth, exploring Jezero delta for signs of life. |
| What evidence suggests that Mars could have supported life in the past? | Evidence of liquid water in the past. |
| What is the main goal of the Europa Clipper mission? | To investigate Europa's habitability, particularly its subsurface ocean. |
| What are the conditions on Europa that may affect life? | High radiation and a cold surface, but it has a liquid water ocean beneath. |
| What is unique about Titan compared to other moons? | It has lakes of liquid ethane/methane on its surface and may have liquid water deep underground. |
| What is Enceladus known for in the search for extraterrestrial life? | It has ice geysers connected to a salty subsurface ocean, providing samples for analysis. |
| What defines life according to the provided notes? | A self-sustaining, organized chemical system capable of Darwinian evolution. |
| What are the four characteristics of life mentioned? | Metabolism, growth, reproduction, and homeostasis. |
| What does complexity theory suggest about life? | Life can be constructed from sub-units, and the number of assembly steps indicates complexity. |
| What is the definition of a habitable planet? | A world containing the basic necessities for life, including liquid water, but not necessarily having life. |
| What are the star system constraints for habitability? | Old enough for evolution, stable orbits, and the right size of the habitable zone. |
| What does the habitable zone refer to? | The region around a star where a planet could maintain liquid water on its surface. |
| What role does volcanism play in habitability? | It contributes to the creation of atmosphere and oceans. |
| What is the carbon-dioxide cycle associated with? | Plate tectonics and its role in maintaining a stable climate. |
| What was the significance of the ALH84001 meteorite? | It contained carbonates and organic molecules but is now thought not to indicate life. |
| What is the importance of having multiple independent measurements in the search for life? | Extraordinary claims demand extraordinary evidence. |
| What is the potential for life on Jupiter's moons? | Ganymede and Callisto show evidence for subsurface oceans, suggesting potential habitability. |
| What is the main challenge for life on Titan? | The surface is too cold for liquid water, but there may be liquid water deep underground. |
| What is the implication of finding no signs of organic molecules on Mars? | It suggests that while life may have been possible, it has not been confirmed. |
| What is a key takeaway from the search for life in the solar system? | There are multiple locations with potential for life, but evidence is still lacking. |
| What does the phrase 'the number of assembly steps is an index of complexity' imply? | More complex life forms require more steps in their chemical assembly. |
| What is the purpose of the planetary magnetic field? | To protect the atmosphere from the solar wind. |
| What are some potential locations for extrasolar life? | Moons with habitable surfaces, super-Earths, water-worlds, subsurface habitability, and orphan planets. |
| What is one requirement for surface habitability? | Being the right distance from a star. |
| What might indicate the presence of life on extrasolar planets? | An analysis of atmospheric gases. |
| What does the Drake Equation estimate? | The number of civilizations with whom we could potentially communicate. |
| What does N represent in the Drake Equation? | The total number of habitable planets in the galaxy. |
| What does f_l represent in the Drake Equation? | The fraction of habitable planets with life. |
| What does f_c represent in the Drake Equation? | The fraction of life-bearing planets with civilization at some time. |
| What does f_now represent in the Drake Equation? | The fraction of civilizations that exist now. |
| What is the main goal of SETI? | To search for deliberate signals from extraterrestrials. |
| What is a significant challenge of interstellar travel? | Current spacecraft travel at less than 1/10,000 the speed of light. |
| What are some difficulties associated with interstellar travel? | Need for efficient engines, enormous energy requirements, and social complications of time dilation. |
| What is Fermi's Paradox? | The contradiction between the high probability of extraterrestrial civilizations and the lack of evidence for, or contact with, such civilizations. |
| What is one possible solution to Fermi's Paradox? | Civilizations are common, but interstellar travel is not due to its difficulties. |
| What is another possible solution to Fermi's Paradox? | Civilizations may destroy themselves before achieving interstellar travel. |
| What does the phrase 'Are we alone?' refer to? | The question of whether life or civilizations exist elsewhere in the universe. |
| What are the implications of interstellar travel for civilization? | It poses enormous difficulties and remains beyond our current capabilities. |
| What are the necessities of life on Earth? | The conditions and elements required for life to exist. |
| Could there be life on Mars? | Yes, it is a subject of scientific exploration. |
| What are the possibilities for life in the outer solar system? | Potential for subsurface oceans on moons like Europa and Enceladus. |
| What are super-Earths? | Planets larger than Earth that may have conditions suitable for life. |
| What is a water-world? | A planet covered mostly by water, which may support life. |
| What is the significance of the Pioneer plaque? | It carries information about Earth and its inhabitants to potential extraterrestrial finders. |
| What is the Voyager record? | A phonograph record containing sounds and images from Earth, sent into space. |
| What is the role of telescopes in SETI? | They look for deliberate communications from extraterrestrial civilizations. |
| What is the estimated number of habitable planets in our galaxy? | Probably billions, according to current estimates. |
| What does the search for extraterrestrial intelligence aim to answer? | How many civilizations exist and how we might communicate with them. |
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skyfalls
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