PCS 182 Midterm: PCS 182 - TEST 1 NOTES
22 Feb 2017
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Take in food and use it for life processes. Life is star stuff: death of middleweight and massive stars, only 8% of stars are ~4 mass of sun, stars 28mos live only a few million years, middleweight ~ (8 to 20) mo, massive ~ 25 mo. Environment requirements for life: mass of star. Age of our sun/earth system: 4. 54 billion years. First simple earth life ~ 3. 7 billion years ago: massive planets. Will gravitationally attract/deflect incoming comets, meteors, asteroids that might cause mass extinctions if they impacted a smaller, bioplanet in system: radiation levels. Cells: damage dna, reproduce chaotically, fail to function, radiation sickness (may be fatal) Mutations may be better adapted to their environment. Ejected by large radioactive nucleus, very short-range heavy (a few cm) Neutron becomes proton and e- = b is ejected by nucleus. Short- range (a few meters in air) Gamma=y and x-rays: gamma arise from nuclear decay and cosmic ray interactions.
