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ENV100Y5 Study Guide - Midterm Guide: Ion, Hyoid Bone, Neoteny

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Monika Havelka
Study Guide

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ENV100 Study Notes
Environment: everything around us with which we interact
Biotic (living things)
oAnimals, plants, forests, soils, etc.
Abiotic (nonliving things)
oContinents, rocks, oceans, clouds, icecaps, etc.
oRoads, buildings, dams, factories, etc.
Environmental science
How natural resources and process support life
How the natural world works
How human activities affect the environment
Scientists try to remain objective
Interactions between humans and the physical and biological world
A social movement dedicated to protecting the natural world
The scientific method
Testing ideas through observation, questioning, and experimentation
The universe works according to natural laws.
Events arise from causes, and cause other events.
We use logic, systematic testing, and our senses to understand natural
Make observations and ask questions.
Formulate hypotheses – preliminary explanations.
Use hypotheses to generate predictions – specific statements that can be
Interpret test results – support or reject hypothesis.
oThe scientific process
Includes peer review, publication, debate.
Uncertainty is a fundamental part of the scientific process.
A consistently supported hypothesis becomes a theory
Some theories lead to a paradigm shift.

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Millennium Ecosystem Assessment
Comprehensive scientific assessment of the state of the world’s ecosystems and their
ability to support life and civilization.
oRapid, extensive changes in the past 50 years
oSubstantial and irreversible loss in biodiversity
Population, poverty, and over-consumption are root problems
oHuman population growth exacerbates environmental problems.
oConsumption of resources has risen faster than population.
Sustainable Development
Use of resources to satisfy current needs without compromising future availability of
What it does
oMeets current human needs
oLeaves future generations with a rich and full earth
oConserves earth’s natural resources
oMaintains fully functioning ecological systems
3 interconnected goals
oSocial goals
oEnvironmental goals
oEconomic goals
Apply knowledge from science and other sources
oLimit environmental impacts
oMaintain functional ecological systems
The time scale of Earth history
Age of universe: ~13.5–14 Ga
oBased on theory + models + Hubble Space Telescope
Age of Sun and solar system: ~4.57 Ga
Based on models of stellar evolution and dating of primitive solar system objects
Age of Earth: ~ 4.54 Ga
oBased on ages of terrestrial rocks + age of solar system + models of solar system
Nebular Theory
oInterstellar cloud inherits elements from previous generations of stars
oGravitational collapse
oSolar nebula is formed

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Solar System
Jovian Plants
oOuter planets
oGaseous and icy
Terrestrial Planets
oRocky and metallic
4.5 Ga Earth was a hostile place
oConstant volcanic activity
oMeteorite impact bombardment
oIntense ultraviolet radiation from the Sun
oNo “free” oxygen in the atmosphere
oNo liquid water
oNo life existed
The early atmosphere
oEarth’s early atmosphere was:
Reducing (oxygen-poor)
Rich in CO2, CO, SO2, CH4, NH3, NOx, H2O(v)
Dense (high atmospheric pressure)
Not hospitable for life as we know it
Atmosphere-hydrosphere-geosphere interacted dynamically
oSurface cooled enough to sustain liquid water
oStill hot – water precipitated and re-evaporated
o- water + atmospheric gases Acids weather of minerals
oOceans began to accumulate (~4.4 Ga)
Hypotheses to Explain Life on Earth
oHeterotrophic hypothesis (“primordial soup”)
Life originated from inorganic chemicals in the ocean
First life forms used organic compounds for energy
oPanspermia hypothesis (“seeds” from space)
Microbes delivered to Earth on meteorites
Organic compounds found in meteorites
oChemoautotrophic hypothesis (ocean depths)
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