What evidence led to the conclusion that earths core is mostly iron

i would say The fact that the Earth has a magnetic field is an independent piece of evidence for a molten, liquid core. A compass magnet aligns with the magnetic field anywhere on the Earth. The earth cannot be a large permanent magnet, since magnetic minerals lose their magnetism when they are hotter than about 500 degrees C. Almost all of the earth is hotter, and the only other way to make a magnetic field is with a circulating electric current. Circulation and convection of electrically conductive molten iron in the Earth's outer core produces the magnetic field. To make the magnetic field, the convection must be relatively rapid (much faster than it is in the plastic mantle), so the core must be fluid. Much of the energy to drive this convection comes from growth of the solid inner core, with the release of energy as the iron changes from solid to liquid.

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from my research i have to the conclusion that decomposers, such as fungi, bacteria and invertebrates, play a critical role in nutrient cycling and without them the earth's ecosystem may not support life as we know it. elements such as carbon, nitrogen and phosphorus exist in limited amounts on earth, although huge amounts of carbon are being released into the atmosphere from underground sources now by humans. it is still extremely important that other nutrients be retained by the process of re-use. decomposers are organisms that are able to chemically break down dead material and make these elements available for use by other organisms. without this breakdown of dead material, dead bodies would pile up. so decomposers also play a role in clean up also. without them, life might not continue as we know it and dead material would overwhelm the earth.    

image result for describe the various types of gene mutationsghr.nlm.nih.gov

the types of mutations include: missense mutation: this type of mutation is a change in one dna base pair that results in the substitution of one amino acid for another in the protein made by a gene. nonsense mutation: a nonsense mutation is also a change in one dna base pair.

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