APES Exam Review Notes

APES Units 1-5 Exam Review 2024

Preparation Strategies

Totally Panicking/Unprepared: Follow the 4-step plan for passing the APES exam in under a week (available in the URP free preview).
Worried/Stressed, but Fairly Prepared: Focus on experimental design and math skills. Review Units 9, 6, and 5 (or whichever units you feel weakest in).
Not Too Worried, Pretty Well Prepared:
- Thank your past self, teacher, and parents.
- Review the units where you score lowest on multiple-choice questions (MCQ).
- Write 3 practice Free Response Questions (FRQs) if your FRQ scores are lower.

Focus Areas for Units 1-5

Topics/terms frequently missed by students on the exam.
Most confusing concepts.
Terms to elevate FRQ writing (must-know vocab).
Tricky FRQ questions from recent exams for each unit.

Unit 1: Ecosystems

Carbon Cycle: Ocean & Atmosphere

Direct Exchange: $CO_2$ moves directly between the atmosphere and the ocean by dissolving into and out of ocean water at the surface.
Increasing atmospheric $CO2$ leads to increased ocean $CO2$ , causing ocean acidification.
Algae & Phytoplankton: Remove $CO_2$ from the ocean and atmosphere through photosynthesis.
Coral, Mollusks, and Some Zooplankton: Take $CO_2$ out of the ocean to make calcium carbonate exoskeletons.
Sedimentation: Calcium carbonate precipitates as sediment and settles on the ocean floor.
Burial: Over long periods, the pressure of water compresses carbon-containing sediments on the ocean floor into sedimentary rock (limestone, sandstone), forming a long-term carbon reservoir.

Nitrogen Fixation

Biotic Fixation: Bacteria in the soil or in symbiotic relationships with plant root nodules convert $N2$ into ammonia ( $NH3$ ).
$N2$ gas is converted into biologically available forms ( $NH3$ or $NO_3^-$ , nitrate).
Rhizobacteria: Live in root nodules of legumes (peas, beans) and fix nitrogen for them in return for amino acids from the plant (mutualism).

FRQ Example: Crop Rotation with Legumes

(e) Describe an advantage of crop rotation using legumes on soil fertility.
Answer:
- Improved nitrogen fixation in the soil.
- Less nitrogen-based fertilizers required.

Trophic Pyramid

10% Rule: Only 10% of energy is passed from one trophic level to the next; 90% is lost as heat/indigestible biomass.
- Explains population sizes of trophic levels.
- Explains what happens when photosynthesis is limited.
- Explains why biomagnification occurs.
- Explains why meat production requires more land than plant production.
$90 \%$ energy lost, $10 \%$ energy transferred at each level.

Unit 1: Must-Know Vocab Terms

Competition
Nutrient availability
Carbon sequestration
Nitrogen fixation
Infiltration vs. runoff
Primary productivity
Trophic levels/10% rule
Energy Transfer

Unit 2: Biodiversity

Ecosystem Resilience

Resilience: The ability of an ecosystem to return to its original conditions after a major disturbance (windstorm, fire, flood, clear-cutting, etc.).
Higher species diversity = higher ecosystem resilience.
High species diversity increases the likelihood that some plant species can survive the disturbance and stabilize the ecosystem (providing food, habitat to animals, anchoring soil, cycling energy, etc.).

FRQ Example: Species Richness

Explain how the species richness of an ecosystem influences its response to environmental stressors.
Answer:
- An ecosystem with greater species richness/diversity is more resilient/resistant to environmental stressors because some species will survive, helping to restore/stabilize the ecosystem.

Ecosystem Services = $ (Monetary Value)

Goods and services provided by natural ecosystems that are beneficial to humans (often monetarily or life-sustaining).
- Regulating: Natural ecosystems regulate and stabilize climate, air quality, water quality, soil, and biodiversity.
- Provisioning: Goods taken directly from ecosystems or made from natural resources (wood, paper, food).
- Supporting: Natural ecosystem processes that sustain ecosystems and allow them to support life.
- Cultural: Money generated by recreation (parks, camping, tours) or scientific knowledge.

FRQ Example: Asian Carp

Describe one impact the introduction of Asian carp could have on the ecosystem services provided by the Great Lakes region.
Answer:
- Improved drinking water quality as carp consume algae.
- Decreased recreational opportunities (boating/swimming) due to increased carp population interfering with activities.
- Decreased fishing due to carp outcompeting native fish species.
- Decreased drinking water quality as carp displace filter feeders like native mussels.
- Decreased algae population resulting in decreased photosynthesis and increased greenhouse gases/global warming/climate change.
- Decreased algae population resulting in decreased photosynthesis and decreased oxygen production.

Keystone Species

(e) Dams are also built by beavers, a keystone species in some North American ecosystems.
- (i) Define keystone species.
  - Has a large effect on its environment relative to its abundance.
  - Increases ecosystem stability OR reduces ecosystem stability when absent.
- (ii) Describe how dams built by beavers can make beavers a keystone species in some ecosystems.
  - Creation of habitats/alteration of existing habitat.
  - Fewer floods maintains habitat stability.
  - Removal of water-borne pollutants increases survival of aquatic life.
  - Entrapment of sediments behind dam creates habitat/reduces turbidity.
  - Reduction of erosion of stream banks.

Unit 2: Must-Know Vocab Terms

Resilience
Gen./species/ecosystem diversity
Ecosystem service
Range of tolerance
Adaptation
Keystone Species

Unit 3: Populations

Biotic Potential: Maximum potential growth rate, with no limiting resources; also called intrinsic rate of increase (r).
- May occur initially, but limiting resources (competition, food, disease, predators) slow growth and eventually limit population to carrying capacity (K).
- Biotic potential = exponential growth.
- Logistic growth = initial rapid growth, then limiting factors limit population to K.

Population Growth Math

Growth Rate (r): Percentage increase in a population (usually per year).
Crude Birth Rate (CBR) & Crude Death Rate (CDR):
- Births & deaths per 1,000 people in a population.
- Example: Global CBR = 20 & CDR = 8.
Calculating Growth Rate (r):
- (CBR - CDR) / 10 = r (Divide by 10 because CBR & CDR are per 1,000, and growth rate is a percentage or per 100).
- Growth rate is always expressed as a percentage.

Doubling Time (Rule of 70)

Rule of 70: The time it takes (in years) for a population to double is equal to 70 divided by the growth rate.
Example: Global growth rate = 1.2%.
70 / 1.2 = 58.3 years. Global population will double in 58.3 years.

FRQ Example: Charlotte's Population Doubling Time

(ii) Based on Charlotte's 2019 growth rate of 1.88%, calculate the year when the population of Charlotte will double, assuming the growth rate stays the same. Show your work.
Answer:
- One point for the correct setup to calculate the year the population of Charlotte will double:
  - Doubling time = \frac{70}{1.88} = 37 years + 2019.
- One point for the correct calculation year the population of Charlotte will double:
  - 2056

Stages of Development

1: Pre-industrial
2: Developing
3: Developed
4: Highly developed

Unit 3: Must-Know Vocab Terms

r vs. K-selected
Generalist vs. specialist
Biotic potential
Carrying capacity
Age cohorts (0-14, 15-44, 45+)
TFR, affluence, female education
Rule of \,70 \rightarrow \frac{70}{r} = 2x time (yrs.)
Phase 1, 2, 3, 4

Unit 4: Earth Systems

Pore Space, Permeability, and H_2O Holding Capacity

Permeability: How easily water drains through a soil.
Pore Space: Larger, connected pore spaces = greater permeability (avoid the term “porosity”).
H_2O Holding Capacity: How well water is retained or held by a soil.
- More permeable = lower H_2O holding capacity.
- Inverse relationship between permeability and H_2O holding capacity.
Effect on Soil Fertility:
- Sandy soil (too permeable) drains water too quickly for roots and dries out.
- Clay-heavy soil doesn’t let H_2O drain to roots or waterlogs them (suffocating them).
- Ideal soil for most plant growth is loam, which balances porosity or drainage with H_2O holding capacity.

Air Properties

Warm air rises (less dense).
Warm air holds more moisture than cold air.
Rising air experiences less pressure and expands in volume.
Expansion causes it to cool (adiabatic cooling).
Cool air can’t hold as much H_2O vapor (condenses to rain).
Sinking air experiences more pressure and decreases in volume.
Contraction causes it to warm (adiabatic warming).
Cool, dry air sinks back down to earth at 30° N & S. Deserts form here due to lack of moisture in sinking air.
Air hits the tropopause & spreads N & S toward the poles
More direct sunlight @ equator, warms air
Warm air rises, expands, causing it to cool H_2O vapor condenses into rain
Condensation causes latent heat release, causing air to continue to rise, expand, and cool
30° = H Pressure , 0° = L Pressure.

Coriolis Effect

Appearance of deflection of objects traveling through the atmosphere due to the spin of the Earth.
Air at 30° moves back to the low pressure of the equator.
Wind between 0-30° moves from W ← E because the Earth is spinning W → E.
Wind between 30°-60° moves W → E because the Earth spins faster at 30° (~870 mph) than at 60° (~500 mph).

Global Wind Patterns

Air moves out from 30° to 0° and 60° due to high pressure at 30° & low pressure at 0° & 60°
- Air rising at the equator = low pressure, air sinking down at 30° = high pressure.
0°-30° winds blow W ← E (Eastern trade winds).
- Drives ocean current clockwise in the N hemisphere, counterclockwise in the S hem.
30°-60° (Ferrel cell) W → E (Westerlies).
- Drives weather patterns of most of the continental US.
60°-90° (polar cell) wind blows W ← E (Polar easterlies).

El Niño & La Niña

Normal Year:
- Trade winds blow equatorial water W ← E.
- Cool H_2O upwelled off coast of South America (cool temperature + good fisheries).
- Warm equatorial current brings heat & precipitation to Australia & SE Asia.
- High pressure in the east Pacific (SA).
- Low pressure in the west Pacific (Australia & SE Asia).
El Niño:
- Trade winds weaken, then reverse (W → E).
- Warm equatorial current brings heat & precipitation to the Americas (N & S).
- Suppressed upwelling off the SA coast (damaging fisheries).
- Cooler, drier conditions in Australia & SE Asia.
- High pressure in the west Pacific (Australia & SE Asia).
- Low pressure in the east Pacific (SA).
La Niña:
- Stronger than normal trade winds (W ← ← ← E).
- Increased upwelling off the SA coast brings cooler than normal conditions, extra good fisheries.
- Warmer & rainier than normal in Australia & SE Asia.

Effects of El Niño & La Niña

El Niño Effects:
- Suppressed upwelling & less productive fisheries in SA.
- Warmer winter in much of North America.
- Increased precipitation & flooding in the Americas (W coast especially).
- Drought in SE Asia & Australia.
- Decreased hurricane activity in the Atlantic Ocean.
- Weakened monsoon activity in India & SE Asia.
La Niña Effects:
- Stronger upwelling & better fisheries in SA than normal.
- Worse tornado activity in the US & Hurricane activity in the Atlantic.
- Cooler, drier weather in the Americas.
- Rainier, warmer, increased monsoons in SE Asia.

Unit 4: Must-Know Vocab Terms

Permeability
Soil texture (sand, silt, clay %)
Stratosphere vs. troposphere
Trade winds & westerlies
Watershed
Rain Shadow Effect
Insolation
El Nino/La Nina

Unit 5: Land Use

Direct Effects of Clearcutting

Soil Erosion:
- Caused by loss of stabilizing root structure.
- Removes soil organic matter & nutrients from forest.
- Deposits sediments in local streams.
- Warms water & makes it more turbid (cloudy).
Increased soil & stream temperature.
Flooding & Landslides:
- Loss of tree shade increases soil temperature.
- Soil has a lower albedo than leaves of trees.
- Loss of tree shade along rivers & streams warms them.
- Erosion of sediments into rivers also warms them.
- Logging machinery compacts soil.
- Increased sunlight dries out soil.
- Loss of root structure = erosion of topsoil & O horizon.
- All of these factors decrease H_2O holding capacity of soil causing flooding & landslides.

GMOs (Genetically Modified Organisms)

Genetically modified crops have genes for drought tolerance, pest resistance, faster growth, and larger fruit/grain.
- Pros: Increases profitability with fewer plants lost to drought, disease, or pests + larger plant size + yield/acre
- Cons: GMO crops are all genetically identical, so genetic diversity is decreased, and susceptibility to diseases or pests is increased.
- Example: Bt corn has been modified with a gene from soil bacteria (Bacillus thuringiensis) to produce a protein that kills many different corn pests.

Synthetic Fertilizer

Shift from organic fertilizers (like manure and compost) to synthetic fertilizers (man-made ammonium, nitrate, phosphate).
- Pros: Increases yield and profits with more key nutrients needed for plant growth (N, P, K) added to the soil.
- Cons: Excess nitrate and phosphate are washed off fields and into nearby waters, where they cause eutrophication (algae blooms).
  - Require FFs for production, releasing CO_2 (climate change).

Irrigation

Drawing water from the ground or nearby surface waters and distributing it on fields to increase plant growth.
- Pros: Make agriculture possible in many parts of the world that are naturally too dry (don’t receive enough rain).
- Cons: Can deplete groundwater sources, especially aquifers
  - Overwatering can drown roots (no O_2$$ access) and cause soil salinization (increase salt level in the soil).

Pesticides

Increase in the use of synthetic pesticides - chemicals sprayed on crops that kill weeds, insects, rodents, and other pests that eat or damage crops.
- Pros: Increases yield and profits with fewer plants lost to pests
- Cons: Can wash off crops in runoff and kill or harm non-target species in local soil or waters (bees especially).
  - Ex: DDT thinned shells of bird eggs, especially eagles Atrazine turns amphibians and fish intersex

Environmental Consequences of Urban Runoff

Decreased infiltration (groundwater recharge).
Rain washes pollutants into storm drains & into local surface waters:
- Pollutants & Effects:
  - Salt (plant & insect death)
  - Sediment (turbidity)
  - Fertilizer (eutrophication, algae bloom)
  - Pesticides (kill non-target species)
  - Oil & gasoline (suffocate fish/kill aquatic insects)

Practice FRQ: Dead Zone in the Gulf of Mexico

(ii) Describe one way that land use practice at location X in the diagram could contribute to the dead zone in the Gulf of Mexico (agriculture).
(iii) Describe one way that urban areas in the Mississippi River watershed could contribute to the dead zone in the Gulf of Mexico.

FRQ Example - Answer: Dead Zone in the Gulf of Mexico

(ii) Describe one way that land use practice at location X in the diagram could contribute to the dead zone in the Gulf of Mexico.
- Accept one of the following:
  - Fertilizer used on croplands is washed into the streams and rivers in the watershed and feeds the growth of algae once it reaches the Gulf.
  - Concentrated animal feeding operations generate large amounts of organic wastes that can move into streams and rivers, feeding the growth of algae once it reaches the Gulf.
  - Treated or untreated (overflows) sewage released from wastewater treatment plants feeds the growth of algae once it reaches the Gulf.
(iii) Describe one way that urban areas in the Mississippi River watershed could contribute to the dead zone in the Gulf of Mexico.
- Accept one of the following:
  - Wastewater treatment facilities in urban areas may release nutrients in treated wastewater and/or overflows, with this effluent flowing into the Gulf.
  - Impervious surfaces in urban areas can increase the movement/runoff of lawn fertilizers or high-phosphate detergents that move onto pavement areas and flow into the Gulf.

IPM (Integrated Pest Management) Basics

Using a variety of pest control methods that minimize environmental disruption and pesticide use.
- Crop rotation - disrupts pest food source (no food when eggs hatch).
- Intercropping - reduces pest habitat/food source.
- Biocontrol (bringing in a natural predator or parasite to control the pest).
- Researching & monitoring pests and targeting methods to specific pest life cycles.

Windbreaks, No-Till, Strip Cropping

Windbreaks: Using trees or other plants to block the force of the wind from eroding topsoil.
- Can be used as a source of firewood, fruit (income).
No-Till: Leaving leftover crop remains in soil instead of tilling under.
- Adds organic matter to the soil (nutrients, soil cover, moisture).
- Prevents erosion from loosened soil.
Strip Cropping: Another name for Intercropping.
- Alternating rows of dense crops (hay, wheat) with rows of less dense crops (corn, soy, cotton) to prevent runoff from eroding soil from less dense rows of crops.
- Can provide habitat for pollinators & other species.

Improving Soil Fertility

*Crop Rotation

Replanting the same crops continuously depletes soil of the same nutrients.
Methods of restoring nutrient levels in the soil (N, P, Ca, Mg).
Crop rotation can allow soil to recover from nitrogen-demanding crops like corn.
Peas/beans (legumes) have nitrogen-fixing bacteria in their root nodules that can return nitrogen to the soil.

Practice FRQ: Reducing Pesticide Use

(ii) Propose one reasonable method, other than crop rotation, to reduce the use of pesticides in agricultural practices while still maintaining a high crop yield.

FRQ Example - Answer: Reducing Pesticide Use

(ii) Propose one reasonable method, other than crop rotation, to reduce the use of pesticides in agricultural practices while still maintaining a high crop yield.
- Accept one of the following:
  - Use integrated pest management to control the insect crop pest.
  - Use a method of pest control that employs a variety of biological, physical, and chemical methods to control the insect crop pest.
  - Reduce stubble/crop residues in follow fields that can harbor the insect crop pest.
  - Apply the pesticide when the insect crop pest is most susceptible.
  - Use intercropping rather than a monoculture to reduce the amount of habitat for the pests.
  - Use pest-resistant genetically modified organisms.

Unit 5: Must-Know Vocab Terms

Clearcutting, selective cutting
GMOs, Pesticides, Irrigation, Fertilizers
Soil erosion
Crop rotation
IPM
Public transportation
Intercropping