Flashcards
C1.7 - Our Changing Planet
Cards in this deck (43)
- 1what shape is the earth?almost spherical
- 2what is the diameter of the earth?12800 km
- 3what is the crust?very thin layer that varies in thickness between 5 km and 70 km
- 4what is the mantle?goes almost half way to the centre of the earth
almost solid put parts of it can flow slowly - 5what is the core?*about half the diameter of the earth
*has a high proportion of magnetic metals iron and nickel
*liquid outer part and solid inner part - 6what is the atmosphere?*surrounds the earth
*most of air is within 1o km of surface
*most atmosphere within 100 km of surface - 7where are all raw materials that we depend on found and what does this mean?found in the crust so they are limited in supply
- 8what do scientists believe about the earths crust and upper mantle?cracked into massive pieces called tectonic plates
- 9how do tectonic plates move?few centimetres a year because of convection currents in mantle
- 10what are convection currents caused by?energy released by the decay of radioactive elements heating up in the mantle
- 11what can happen at plate boundaries?huge forces build up and rocks give way changing shape or moving suddenly causing earthquakes, volcanoes and mountains
- 12can scientists predict exactly when earthquakes and volcanoes will happen?no
- 13what did Alfred Wegener do in 1915?put forward idea of continental drift from one supercontinent Pangaea
- 14why did other scientists not accept Wegener's theory?could not explain why continents moved as they believed the earth was shrinking as it cooled
- 15what happened in the 1960s?new evidence and the theory of plate tectonics was developed
- 16when do scientists believe the earth was formed?4.5 billion years ago
- 17what do scientists believe about the earth surface in the first billion years?covered with volcanoes that released carbon dioxide, water vapour and nitrogen
- 18what happened as the earth cooled?the water vapour condensed to form oceans
- 19what was the composition of the early atmosphere?mainly carbon dioxide, some water vapour, nitrogen, some methane and ammonia
- 20what happened in the second two billion years?bacteria, plants and algae evolved
- 21what did algae and plants do?used carbon dioxide in photosynthesis and this released oxygen
- 22what happened to the atmosphere as plants increased?carbon dioxide decreased and oxygen increased
- 23what did plants that produced oxygen probably evolve from?simple organisms like plankton and algae in ancient oceans
- 24how did molecules of living things form?we do not know as there is insufficient evidence
- 25what was the miller-urey experiment?1952 two scientists mixed water, ammonia, methane and hydrogen and a high voltage spark to simulate lightening and after a week amino acids the building blocks for proteins had been produced
- 26what has happened since the 1950s?theories about the early atmosphere have changed and scientists have been able to produce amino acids using other mixtures of gases
- 27what theory is the most accepted?the organic molecules of carbon, hydrogen, oxygen and nitrogen molecules formed a 'primordial soup' and amino acids in this mixture combined to make proteins from which life began
- 28why has no theory ever been proved?there is not enough evidence to prove any
- 29how did carbon from the atmosphere end up in animals?plants took up carbon and animals ate the plants
- 30what contains carbon that is found in plant and animal remains?sedimentary rock and fossil fuels
- 31what was limestone formed from?shells and skeletons of marine organisms
- 32how were sedimentary rocks likely formed?carbon dioxide dissolved in oceans forming insoluble carbonate compound that were deposited on the sea bed and became sedimentary rocks
- 33what happened 200 million years ago in the atmosphere?they stabilised and were much the same as today
- 34what is the composition of the atmosphere?*4/5 nitrogen
*1/5 oxygen
*1% carbon dioxide, water vapour and noble gases - 35how can gases in the air be separated?they all have different boiling points so by fractional distillation
- 36what is fractional distillation done of to produce what?*liquid air
*pure oxygen and liquid nitrogen - 37what is the air cooled to?-200'c
- 38what happens in the fractional distillation of air?nitrogen separated from oxygen and argon and further distillation is needed to produce pure oxygen and pure argon
- 39what has the amount of carbon dioxide in the atmosphere been like for the last 200 million years?remained about the same
- 40why has levels of carbon dioxide stayed the same?various natural processes remove carbon dioxide into and out of the atmosphere to achieve a balence
- 41what is important in maintaining a balance of carbon dioxide involving oceans?carbon dioxide dissolves in water to form inorganic carbon compounds
- 42describe the carbon cycle*co2 taken in photosynthesis in plants
*plants respire releasing co2
*plants die containing organic compounds
*animals eat plants containing c
*animals respire releasing c02
*animals die leaving organic compounds
*burial and sedimentation of dead plants and animals makes fossil fuels that contain the organic compounds
*decomposers decay plant and animal waste and respire releasing co2
*fossil fuels are burnt releasing co2 in smoke - 43in the recent years what has increased dramatically and why?amount of carbon dioxide human activity has released into the atmosphere as a result of the large increase in the amount of fossil fuels burnt
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- GCSE Chemistry (C1) Flashcards on C1.7 - Our Changing Planet, created by scottjowett on 09/06/2015.
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