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BIOL 215- Midterm Exam Guide - Comprehensive Notes for the exam ( 34 pages long!)


Department
Biology
Course Code
BIOL 215
Professor
Neil Price
Study Guide
Midterm

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McGill
BIOL 215
MIDTERM EXAM
STUDY GUIDE

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BIOL 215 - Week 1
The Origins of Earth and Life (Ch. 2,3,4)
Big Bang Theory
-Between 10-15 bya
-Quarks form protons and neutrons
-Expansion , formation of protostars
-Protostars burn and produce heavier elements such as Iron
-Protostar explodes as supernova and forms our solar system about 4.6 bya
-Sun is created which is essential to the beginning of life
-Planets solidify:
Earth is in a perfect location orbiting around the sun where its not too cold nor too
hot.
Oxygen also allows formation of ozone layer
-Earth was originally molten; mostly made up of iron, magnesium, silicon, and oxygen.
-Oldest rocks formed around 4.28 bya
-Earth only cooled (formed crust) around 4.2-4.1 bya
Magma crystallizationā€”> igneous rocks erosionā€”> sediments litriļ¬cationā€”>
Sedimentary rocks
Both igneous rocks and sedimentary rocks metamorphosisā€”>metamorphic rocks which
can melt back into magma
-Can calculate how old minerals are (ie. date of birth of stars and earth) using the
radioactive decay of uranium into lead and its half life with how much lead is present or
uranium is remaining.
Sedimentary Rocks
-Oldest at the bottom
-Strata identiļ¬ed by fossils it contains
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-Fossils in upper strata most likely living organisms
Earthā€™s Early Atmosphere
-Meteors and comets bombarded Earth 4.5-3.8 bya (supply lighter elements and frozen
gases)
-Atmosphere generated by volcanic out gassing (80%) and impact bodies (20%)
-CO2 (100-1000 greater than current levels), Nitrogen, and H2O, plus trace amounts of
Hydrogen, S gases, ammonia, and methane
-Atmosphere reducing
-No free oxygen
-Atmospheric pressure was very high
-Concentration of CO2 declined because it
1. dissolved in the oceans
2. was absorbed into rocks
-Biology greatly reduced CO2 levels and increased O2 levels
Earthā€™s Ocean
-Once Earth cooled, water condensed and formed oceans
-Earth had liquid water on surface by 3.9 bya
-Zircons require water and low temp. to form
Sea Salt
-Gases dissolved into water because of high solubility
Biomarker evidence for life (around 3.85 bya)
-Indicators of life such as molecules and isotopic signatures
-Some of these include carbon 12 and carbon 13
-RuBP enzyme react with carbon 12ā€”> organic matter will be enriched by 2-3 %
Fossil evidence for life (around 3.5 bya) *** Different from biomarker evidence because
depending on the scientiļ¬c method used results will differ
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