Exam 2 Flashcards
T or F: population growth is always constant
F: population growth is never constant
How much have global growth rates increased after 1950?
2.3%
How much has the rate of human population been declining since 1970?
0.8%/year
If population growth never declined, what would be the human population as of 2020s?
12 billion
What main event in China caused a rapid decrease in population and led to famine of 40 million people?
Great Leap Forward
What countries have slower population growth rates?
Italy, Japan, South Korea, Singapore
Why is the population of Japan shrinking?
Japanese are not having enough children
What are the population controls 2000 years ago?
Available resources, disease (e.g., typhus, dysentery, pneumonia, leprosy, plague, cholera), and conflict
What caused the collapse of the Akkadian Empire in 2100 BC?
Typhoid fever and plague
In 600-1350, there was a 40% decrease in population in Western Europe. Why?
Black plague
What was the infant mortality rate of England in 1830?
250 infants deaths per 1,000 births
What was the mortality rate of children from 0-5 years old in England in 1830?
430/1,000 births
What was the US life expectancy at birth in 1900?
47
What was the US life expectancy at birth in 1925?
59
What was the US life expectancy at birth in 2020?
79
What determines human population growth?
- Balance between in and out (births and deaths)
- Death rate
- Total fertility rate
- Replacement fertility
Equation for death rate
Death rate = f{conflict, disease, famine}
Total fertility rate (TFR)
Total number of children/offspring per woman
What was the TFR in 1960?
5 offspring per woman
Replacement fertility
TFR that keeps population size stable
I.e., describes how many offspring a women needs to have to maintain population size
What is the rule of thumb for replacement fertility?
2.05
What can we conclude when reduced poverty leads to reduced population growth?
TFR declines with higher income (GNP)
What can we conclude when universal education leads to reduced population growth?
Countries that have higher education for women show lower TFR
in 1851, people had a 60% chance of living to
30
in 2011, people had a 60% chance of living to
90+
What does the number of Earth’s human carrying capacity depend on?
- state of the earth (degrade of environment -> carrying capacity shrinks)
- how individuals live (what are the resource demands for the entire Earth’s population)
What meat resource is very demanding?
Beef
_____ is a resource-demanding fish
Salmon
Molecules
Combinations of two or more atoms (N2, CO2, NaCI, H2O)
List the bonds from strongest to weakest.
- Covalent bond
- Ionic bond
- Hydrogen bond
Covalent bond
Atoms share electrons (CO2)
Ionic bond
Atoms bound by electrical attraction (NaCI = Na+ + CI-)
Hydrogen bond
“Partial ionic bond” between molecules
Describe a water compound.
Partial charges at opposite ends of molecule
“Polar” molecule
high heat capacity
measure of amount of heat energy that must be absorbed by the substance to raise the temperature 1 degree C
What makes a solution acidic?
If H+ (protons) concentration greater than OH- (electrons)
What makes a solution basic?
If OH- (electrons) concentration is greater than H+ (protons)
T or F: only an acidic solution can be lethal.
F: both acidic and basic solutions can be lethal
What happens when soil is basic?
Nutrients (e.g., P, Mn) not soluble (unavailable to plants)
Dark leaves indicates ______ limitation/deficiency.
Phosphorus
What happens when soil is acidic?
Toxic metal ions (e.g., Al) are more available/soluble
In acidic soil, as pH drops and Al availability ________, plants grow ______.
Increases; slower
Atoms
Elemental units (“building blocks of matter”)
Isotopes
Same number of protons, but different number of neutrons
What are the two isotopes of hydrogen?
Deuterium (0.02%) - stable isotope (not radioactive, does not disappear)
Tritium (trace) - radioisotope (radioactive, spontaneous decay occurs)
The atmosphere (CO2) is mostly made up of which carbon isotope?
12C
Grass and shrubs discriminate against which carbon isotope?
13C
What is the preferential carbon isotope for both grass and shrubs?
12C
What is the salmon life cycle?
Salmon eggs hatch in a freshwater stream
Salmon return back to the stream they were born in
Female lays egg; male fertilizes eggs
Salmon die and rot
How do the nitrogen isotopes in marine and terrestrial environments differ, and in what ways do salmon contribute to the nitrogen cycle on land after their death, particularly regarding terrestrial invertebrates near streams?
[Marine 15N/14N] /= [terrestrial 15N/14N]
Marine food → salmon body → death, decay → terrestrial
Terrestrial invertebrate animals near stream: up to 70% of N in body
Salmon act as fertilizers for animals that live on land far from the ocean
Salmon collect N from the ocean
Salmon deposit N after death
What are four different independent developments of agriculture?
- China: rice
- Fertile crescent: wheat
- Central America: potatoes
- Mesoamerica: corn, squash
Describe the evolution of agriculture
Subsistence agriculture: production for family
Intensive traditional agriculture: animals + irrigation + fertilizer → excess for sale
Modern intensive agriculture: monocultures since ca. 1950
Green Revolution: intensification of industrial agriculture + crop (artificial genetic) selection; since 1960
Today: ca. 40% of Earth’s surface converted to agriculture and raising livestock
What are the functions of soil?
- Regulates water cycle (controls flow of rain, snowmelt)
- Productivity
- Filters pollutants (sequester or detoxify)
- Nutrient cycling (organic —> inorganic)
Autotrophic plants
CO2 + H2O —> carbohydrate
CO2 + H2O + NO3 + PO4 —> protein
Heterotrophic fungi, bacteria
Carbohydrate —> CO2 + H2O
Protein —> CO2 + H2O + NO3 + PO4
Soil = mix of ______ + _______
Organic; inorganic
Rhizosphere
Interface between plant roots and soil
Where do rhizobium bacteria “infect” legumes?
Nodules/roots
How do plants respond to the infection of Rhizobium bacteria, and what mutual benefits arise from this relationship?
Plants respond by forming a scar tissue around the bacteria
Both plant and bacteria benefit
How do Rhizobium bacteria break down the strong triple covalent bonds of nitrogen?
Convert N2 (gas) → NH4 (ammonium)
Plants → N (organic)
Soil decomposers: N (organic) → NH4 (ammonium) → N2 (gas)
where are Mycorrhizal fungi located on plants?
partly inside and outside plant root
What are some soil threats?
- non-native earthworms
- irrigation practices
Explain the mutualistic symbiosis of mycorrhizal fungi and plants
Plant root gives some carbohydrate to fungi
Fungi take in water and nutrients from soil environment and feed it to plant
What percent of all freshwater use is for crop irrigation?
70%
Why is over-irrigation a problem?
Over-irrigation —> waterlog plant roots —> poor growth, death
Soil becomes soggy
Roots need oxygen
Too much water = water diffuses much slower
Plants are not getting enough oxygen
Salinization
Buildup of salts in surface of soil layers
What occurs during salinization?
Evaporation removes water, leaves salts
Water comes up to surface and evaporates
Salts in the water do not come ip to surface and are left behind
Why are conventional irrigation practices wasteful?
Less than Half of water reaches plants
Most of the water released from the rotators is evaporated
What is drip irrigation and why is it better than conventional irrigation practices?
In drip irrigation, water drips out slowly (reduces chance of evaporation)
Conserves water, saves money and reduces salinization
Why are monocultures an issue?
Economically efficient, but risk of “all eggs in one basket”
Reduced global diversity of crop plants
What is the problem with pesticide use?
Pesticides gradually become less effective as pests evolve resistance
The few pests that survive pesticide reproduce and pass on pesticide resistance genes to next generation
GMOs
Organisms whose genetic constitution has been altered by engineers with a specific outcome in mind
What is the purpose of GMOs?
Attempt to ramp up food increase
What happens to organisms that go through GMOs?
Organisms grow bigger and faster
Artificial selection
Manipulating organism’s genetic material by selecting mating, harvest
Artificial selection is a selection of
Who mates with who
What are examples of artificial selection?
Different dog breeds
- all come from same genetic stock (wolves)
Teosinte —> corn
Wild mustard (origin)
- cabbage
- broccoli
- kale
- cauliflower
- kohlrabi
Genetic engineering
Adding, deleting, or changes segments of DNA
Recombinant DNA
combination of original DNA plus some modification
Example of recombinant DNA
What are benefits of GMOs?
- Increase food production without nature conversion
- Less pesticide use
Eutrophication
Over-fertilization of the natural environment
In eutrophication, phytoplankton are supplied with _____ and _____, leading to extreme phytoplankton growth.
Sulfur; phosphorus
What meat has the greatest grain feed demand?
Beef (20 kg feed/kg produced)
What meat has the lowest demand of grain feed demand?
Chicken (less than 5 kg feed/kg produced)
Aquaculture
Raising aquatic organisms under controlled conditions
What are benefits of aquaculture?
reliability (controlling conditions)
Can be small-scale
Reduce fishing of wild stocks
Uses less fossil fuel than capturing fishing (Less use of boats to travel from place to place to capture fish)
What are environmental impacts of aquaculture?
high density –> disease, antibiotics
Waste production: high amounts of waste (urine, feces) is produced
Farmed fish escape to interbreed with or spread disease to wild fish
Animals often fed fish meal (e.g., salmon chow)
By catch equation
By-catch impact = discards (what we throw away)/total caught (what we catch)
What are some reasons for the extinction of Steller’s sea cow?
- slow
- Similar to beef in taste
- Low reproductive output (1 calf/litter, 12 month gestation)
- Only found in the pacific northwest (low distribution)
- Blubber for cooking (rendered for lamp oil)
What is the main cause o death for marine whales?
collisions with boats
What is the origin natural gas and petroleum come from?
marine plants
Crude oil
sludgy hydrocarbon mix
Oil was first used 4,000 years ago as what?
asphalt
When did modern extraction of oil begin?
1850s
fracking
hydraulic fracturing
Sulfure in coal -> ______ + _____ -> ________ -> _________ + ______
SO2 (sulfur dioxide); H2O (water); H2SO4 (sulfuric acid); 2H+; SO42-
Anything below ___ pH is considered to be an effect of acid precipitation
5
Where is most of acid precipitation?
Ohio Valley (< 4.3)
Oil (tar) sand include the following:
clay, sand, water, and viscous bitumen
Oil (tar) sands are ____ with a mix of _____
sand soil; acid asphalt
What is required to liquify oil (tar) sands?
Heat
Oil (tar) sands is ____ of the world’s total oil resevres
2/3
Oil (tar) sands have a high ____ content
sulfur
Shale oil
rock rich in organic kerogen
Kerogen is converted to oil via what process?
pyrolysis
Pyrolysis occurs at what temperatures?
445-500 C
Methane hydrates
crystalline solid (CH4 molecules, each surrounded by a cage of water molecules)
Where are methane hydrates located?
Arctic regions and marine sediments at depths > 300 m
How much oil was spilled in the Exxon Valdez spill?
11 million gallons
What happened in the Deepwater horizon blowout?
Drillsite on fire
Oil spills ended up on the beaches of Louisiana, Texas, etc.
Beaches covered with layer of oil
How much oil was spilled during the deepwater horizon blowout?
134 million gallons (over 87 days (5,000 ft))
What are the most common type of oil spills?
Microspills
How much of petroleum inputs in ocean are from a natural source?
48%
How much of petroleum inputs in ocean are from a source greater than natural?
8%
What are the biggest threats in developing nations in regards to indoor air pollution?
Cigarette smoke (first and secondhand smoke)
Indoor fires
What are the biggest threats in industrialized nations in regards to indoor air pollution?
Cigarette smoke (first and secondhand smoke)
Radon (naturally occurring radioactive gas)
Radon is associated with what type of cancer?
Lung cancer
Describe radon gas
Radioactive
Colorless, odorless
occurs naturally
Where does radon gas come from?
Uranium ores
Granite, gneiss, and schist
Atmosphere
layer of gasses surrounding planet
What is the function of the atmosphere to humans?
- absorbs solar radiation (esp. UV)
- transports & recycles water (and other materials)
- determines climate
List the invariant gasses and their percentages
nitrogen (78%)
oxygen (21%)
argon (1%)
List variable (greenhouse) gasses:
Water vapor
carbon dioxide
methane
nitrous oxide
ozone
chlorofluorocarbons (CFCs)
Climate
long term pattern of atmospheric conditions
Global warming
increase in Earth’s average surface temperature
What are factors that influence climate?
- Sun energy source; provides heat for Earth
- Atmosphere - absorbs, reflects, transmits energy
- Oceans - stores, transports energy, and moderates heat
Global warming potential
relative ability of one molecule of a greenhouse gas to contribute to global warming over 100 years
CO2 concentration has increased by _____ (_____ parts/thousand) since Industrial Revolution
50%; 280-420
Why are non-native earthworms a threat to soil?
Reduce soil biodiversity, productivity
Where do non-native earthworms come from?
Asia
In what ways does intensive agriculture cause environmental harm?
Fertilizer pollution
Pesticide pollution
Water depletion (irrigation)
Fossil fuel use
What was the goal os the Green Revolution?
increases crop output per area land
Example of recombinant DNA
Bt-protected crops
Explain how Bt-protected crops are an example of recombinant DNA?
Soil bacterium, Bacillus thuringiensis
Produces toxic to defend against predators
Toxin-producing gene is taken → Bt endotoxin
95% U.S. soybeans, 85% corn, and 90% cotton GM
US = 40% global GMA production)
What are scientific concerns about GMOs from least to most increasing likelihood?
- Human health risks (No evidence suggesting GMOs affect human health)
- Can tansgenes for pest resistance “jump” from crops to weeds (–> “superweeds”)?
- Pests will evolve resistance to Gm crops just as with pesticides?
What are socioeconomic and political concerns regarding GMOs?
Ethics of “playing God?”
Food supply risk?
- Adequate testing? Is outside oversight adequate?
The fish problem
- Decrease in water quality of freshwater
- Increase in demand for (water) power
- Overfishing of freshwater fish
shifting baselines
change evaluated based on current state
each generation = new baseline
What is the assumption of shifting baselines concept?
“current state is normal”
Why is by-catch a problem?
“Non-target” species caught
Non-specific equipment (e.g., nets)
Estuaries mix ____ and ____
fresh and saltwater
Name two ocean threats
- Plastic debris
- Microplastic debris
What does the sankey diagram say about energy use?
33% of energy goes to doing things for us
67% of energy contained does nothing for us
Wasted; dissipated as heat
Geothermal
heat from the ground
Industrial Smog
Burning sulfur-rich coal (or oil):
- SO2 - respiratory, cardiovascular
- SO2 → sulfuric acid (acid ppt)
-Ammonium sulfate (eutrophication)
-CO2 (GHG)
- CO - respiratory
London’s 1952 “Killer Smog”
December 1952, thick smog over London
Smog from industrial pollution, fossil-fuel combustion
Killed ca. 10,000 people
Photochemical Smog
From reaction of sunlight with pollutants (VOCs, ozone)
“Brown-gree air smog”
Hot, sunny days + autos
Earth’s Energy Budget prior to human modification
Incoming solar energy/radiation
- Some absorbed by clouds
-Large amount absorbed by gasses in atmosphere
-Most absorbed by land and oceans
In equilibrium: in = out
- Balanced by energy that leaves
Earth’s Energy Budget after human modification
Amount absorbed by atmospheres and cloud have increases
Not balanced
Less energy/heat leaving
- Earth is warmer
What is the global warming potentials of carbon dioxide?
1
What is the global warming potentials of methane
23
What is the global warming potentials of nitrous oxide
296
What is the global warming potentials of
12,000
What are the take home messages of
Since humans in the industrial revolution began contributing to atm CO2, concentration has spiked significantly
Greater increase over a shorter period compared to over thousands of years before human modification
Current: highest CO2 in past 800,000 years
CO2 continues to rise
Temperature lags behind CO2
Pre-industrial: CO2 and average global surface temperature are relatively constant with each other prior to the industrial revolution
CO2 and global temperature are tightly linked/coupled
CO2 absorbs heat energy
Global surface temperature and CO2 concentration varied naturally before humans modified the atmosphere
Temperature has varied about 10 C (no human contribution)
Methane
anaerobic (w/o oxygen) process
What has contributed to the increase in methane since 1750?
Fossil fuel extraction
Landfills (oxygen is absent)
Rice paddies (oxygen is absent)
Cattle (gas digestion)
- Release methane into atmosphere
How much has methane increased since 1750?
155%
What has contributed to the increase in nitrous oxide since 1750?
Auto emissions
Feedlots
Agriculture
How much has nitrous oxide increased since 1750?
17%
One cow emits __________ liters of ____ gas/day
800-1000; CH4
_______ cuts methane emissions by 40%
Oregano
What is Happening: Physical Changes
Ocean temps increasing
Greater incidence of severe storms
Sea level rising (3 mm/year)
- Ice is melting faster
Acidification
Ocean is becoming more acidic
Half of CO2 emitted in atm gets dissolved into ocean
CO2 reacts with water
