100% Correct Answers Graded A+ 2024
Main questions of course - Correct Answer 1. How do humans alter earth
2. how do human alterations affect the biosphere
3. What can be done to alleviate human alterations of the biosphere
Oceanic CO2 - Correct Answer -25% of carbon from CO2 gets taken up by oceans
-Caused the average ocean ph to drop by 0.1 units and because ph is a log scale
resulted in 26% increased acidity causing major changes to ocean ecology
nitrogen fixation - Correct Answer process of converting nitrogen gas into nitrogen
compounds that plants can absorb and use
Nitrogen in Ecosystems*dont understand* - Correct Answer added to ecosystems
through fixation by microorganisms and limits the growth of many ecosystems
Large mammal biomass - Correct Answer 97% of large mammal biomass is
human(30%) or domestic animals(67%)
Human water use - Correct Answer -35% of all of the earths usable water goes
toward agricultural needs while 15% goes to other human needs
-37% of rivers globally including 2% in the US are UNimpeded by dams which makes
it hard for microorganisms and fish to travel
Extinction rate on earth - Correct Answer -100-1000 times the background rate
-Yearly loss of 11-58k species
-Rates only comparable to 5 times in last 500 million years which could indicate 6th
mass extinction
biotic homogenization - Correct Answer Certain species coexist well with humans so
they are favored in many areas throughout the world, decreasing overall biodiversity
in the world
,Examples of biotic homogenization - Correct Answer -mixing of biota(plant or animal
life native to a certain region) across oceans
-many continental regions have 20% of plant life as exotic(not native to the area)
Big picture behind planetary boundaries - Correct Answer All these disturbances are
connected to one another so one major change could result in an even large change
somewhere else due to the many indirect consequences
Anthropocene - Correct Answer a new geological period dominated by human
destabilization of the earth's natural systems
Common Geological time units - Correct Answer Eras: Hundreds of millions of years
periods: 50-200 million years
epoch: 5-30 million years
Formal criteria for new geological time units - Correct Answer 1. Must be
stratigraphic evidence(evidence in rock layers) for start date all over the world.
2. Must persist for millions of years
3. accompanied by a mass extinction
"Golden Spike" - Correct Answer (GSSP) Global Stratotype Section and point and
refers to evidence in geological strata that signifies the start of a new geological
stage of time.
Example of golden spike and geological time shift - Correct Answer Boundary
between the cretaceous and paleogene periods that occured 66 million years ago
with a meteor impact
- layer of iridium rock not common to earth found in strata all over the world
- global extinction of dinosaurs occurred
How many mass extinctions have there been? - Correct Answer five(not including
the one currently going on)
, When should the Anthropocene begin?(Scientist arguements) - Correct Answer
1.mega faunal extinctions 50-10k years ago which was was defined by humans
growing in numbers and over-hunting mega faunal animals
2. Dawn of agriculture 11-8k years ago when hunting stopped and we stayed in one
place to farm
3. Globalization and columbian interchange(1492-1620)
4. Industrial revolution(1760-1880)
5. The great acceleration(1945-1965) {acceleration of population, factories and the
rise of nuclear}
Greatest ecological impacts of humans(most to least) - Correct Answer 1. Nitrogen
fixation
2. Water use
3. Land transformation
4. CO2 concentration rise
5. Ocean acidification
6. Bird extinction
7. Plant invasion
Planetary Boundaries - Correct Answer Limits between which global systems must
operate to prevent abrupt and irreversible environmental change
Planetary Boundaries that have been crossed - Correct Answer 1. Biogeochemical
flows of Nitrogen and Phosphorous(Nitrogen fixation)
2. Genetic diversity (biodiversity loss)
Success story of planetary boundaries - Correct Answer Restoration of the ozone
layer
Non-linear dynamics - Correct Answer Outcome is not proportional to input
- to revert back to a stable state, it will take more effort than getting to where you are
now(It takes much less equipment to pollute a pond than to clean it up after it has
been polluted)