AP Environmental Science Exam Review Notes

Digital Exam Overview

Beginning in Spring 2025, the AP Program is accelerating the transition to digital testing.
Students will take digital exams using the Bluebook app.
AP coordinators and proctors will administer digital exams using the Test Day Toolkit web application.
Paper exams will only be available to students approved by the College Board.

Before Test Day

Ask your teacher or AP coordinator when Bluebook will be installed on your school-managed device.
If testing with a personal device, download Bluebook.
Open Bluebook and click "Test Your Device" to ensure your device meets requirements.
Sign in with your College Board account.
Locate your upcoming exam under "Your Tests" on the Bluebook homepage.
In April, try a test preview in the Practice and Prepare section.

General Reminders

Answer the questions you know first.
Guess on everything; no blank answers.
FRQ answers should include:
- Habitat destruction leading to a decline in biodiversity (relate to prompt).
- Respiratory illnesses such as asthma.
- Ecosystem services related to humans.
- Economic impact (jobs or money).
- Environmental impact causing organisms to be outside their range of tolerance.

Strategies for Success

Educate people on a topic to encourage action.
Educating women can lead to population decline.
When in doubt, choose the option that causes human population to decline or not grow.
Tax undesirable things and subsidize desirable things.
Trust your first instinct; avoid changing answers.

Free Response Questions (FRQs)

Use precise language, as if you were speaking at a college level.
Be specific; convince the reader you understand the material.
Instead of saying something changes or is affected, indicate increase/decrease and explain why.
Read prompts or questions TWICE
Eliminate wrong answers on MCQs and choose the best answer; use the crossout feature in Bluebook.
Make a short outline on scratch paper for FRQs, then compose a clear, concise, specific answer.
Label parts of an FRQ within the box (e.g., A i), A ii)).
FRQs will be done electronically.
There will be several prompts per box.
Label the sections within the box and respond to ALL prompts

Bluebook Features

Line Reader: Available to help students track longer passages or focus on specific things. Access by clicking “More” in the top right hand corner, then line reader
Highlighting and Underlining: Available by selecting text and choosing the highlight and notes feature in the top right
Cross Out: Students can cross out answers to eliminate distractors
Subscript and Superscript: Available by selecting the value to change, and then selecting superscript or subscript.
Click on the arrow next to the word “Directions” on the top left to review the math symbols and directions for typing superscripts and subscripts.

What to Bring on Test Day

Fully charged device with Bluebook installed (should hold a charge for 4 hours).
Device's power cord and/or portable charger (outlet access not guaranteed).
Pencil or pen with black or dark blue ink.
Scratch paper will be provided.
External mouse (if used).
External keyboard if using a tablet/iPad (required for fully digital exams, recommended for hybrid exams; not permitted on laptops).
Approved photo ID (if not testing at your regular school).

Taking the Exam

Connect to Wi-Fi, sign in to Bluebook, and complete a check-in process.
Proctor will read instructions, collect prohibited items, and provide a start code.
Enter the code into Bluebook to begin the test.
Most AP Exams have 2 sections, sometimes divided into parts.
The app indicates time remaining in each section/part; you can move back and forth until time expires.
Breaks occur between sections (no scheduled break for AP Seminar).
Hybrid AP Exam: use an exam booklet to enter FRQ answers in Section II.
Bluebook will submit answers automatically at the end of the test. Do not close your device until dismissed.
Follow app instructions if submission fails. All answers are saved during testing.

Math Formula Sheet Reminders

Calculators: Allowed (4-function, scientific, and graphing calculators). Calculators are also provided within the BlueBook app for digital testing. Refer to the AP® calculator policy on the College Board® Website.
Pre-Algebraic Word Problems: Practice dimensional analysis.
Multiple Choice: 6-9% of questions are math-related (4-8 out of 80 questions).
Rule of 70 is a common MC question topic.
No work needs to be shown for MC questions.
Free Response: There are 3 FRQs in 70 minutes. Question #3 is 60% math, and requires work to earn half the points.
No Formula Sheet: Memorize simple formulas.

Changes to Math Requirements (Post-2023)

Units in Setups: Units are no longer required to earn setup points.
- Setups must have correct numerators and denominators in the correct order.
Units in Answers: Answers require units only if not provided in the question stem.
Example: How many individuals can the windmill provide electricity to? 78 - this is correct as the unit (individuals) is provided in the prompt
Example: How much energy would be provided? 4500 KWH - this requires a unit as none is provided in the prompt.
Work Provided: Due to allowing a calculator, answers no longer have to have work provided. The answer point can be earned with no work, but no setup point would be earned.

Math Formulas - Population

Rule of 70:\text{# of years to double} = \frac{70}{\text{Annual % growth rate}}
Population Growth Rate (r): $r = \frac{[(b + i) - (d + e)]}{\text{total population}} \times 100$
- r = population growth rate
- b = birth rate
- i = immigration rate
- d = death rate
- e = emigration rate
Crude Growth Rate: $r = (CBR - CDR) / 10$
Per capita: $\frac{\text{population measurement}}{\text{population size}}$

Math Formulas - Change in Data

Percent Change: $\% \text{ increase} = \frac{(\text{New Value} - \text{Initial Value})}{\text{Initial Value}} \times 100$
- Positive value = % increase
- Negative value = % decrease
Rate of change: $\frac{(\text{final value} - \text{initial value})}{(\text{final year} - \text{initial year})}$

Math Formulas - Dimensional Analysis

Show all setup on FRQs and use labels for every step.
Clearly identify the final answer.
No naked numbers
If you don’t know how to do Part A, but you know that you need to carry the value from Part A into Part B - make up a number for A and plug into B and solve
D - dependent variable
R - responding variable
Y - found on the Y axis
M - manipulated variable
I - independent variable
X - found on the X axis
Know metric conversions (e.g., 7 days/week, 24 hours/day, 60 minutes/hour, 365 days/year, 12 months/year).

Math Formulas - Other Formulas

Half-life: $\text{amount remaining} = (\text{original amount}) \times (0.5^x)$ , where x = number of half-lives
Total energy used: $\text{kW} \times \text{hours} = \text{kWh}$
Energy Efficiency: $\text{efficiency of step 1} \times \text{efficiency of step 2} \times … \times 100$
Primary Productivity: $\text{NPP} = \text{GPP} - R$
10% rule: 10% of energy moves from one trophic level to the next

Math Formulas - Diagrams

Understand soil triangle diagram
Understand DOSE RESPONSE GRAP
Understand survivorship curves Types I (humans), II (songbirds), and III (frogs)
Understand Exponential and Logistic growth
Understand demographic transition in 5 stages
Understand Organic Pollution Diagrams

Chemistry Review by Shapiro

pH is a measure of the amount of $\text{H}^+$ and $\text{OH}^-$ ions in a solution.
Acids have a higher concentration of $\text{H}^+$
Bases have a higher concentration of $\text{OH}^-$
pH scale is LOGARITHMIC, where each value is 10x greater than the next higher value.

Chemistry - Acid Formation

$\text{NOx}$ (from cars) + $\text{H}2\text{O}$ -> $\text{HNO}3$ (nitric acid)
$\text{SOx}$ (from coal) + $\text{H}2\text{O}$ -> $\text{H}2\text{SO}_4$ (sulfuric acid)
$\text{CO}2$ (from fossil fuels) + $\text{H}2\text{O}$ -> $\text{H}2\text{CO}3$ (carbonic acid)
Formation of an acid causes the pH to decline

Chemistry - Acid remediation and Impacts

Acidic environments (acid rain/mine drainage) may be remedied by adding a base like limestone.
Acid rain results in:
- Loss of nutrients from soil (clay attracts acid, releases metals).
- Metals such as $\text{Al}^{3+}$ may be leached out and runoff into groundwater.
- General forest decline.
Ocean becomes acidic due to carbonic acid from excess $\text{CO}_2$ from burning fossil fuels.
Cannot remediate ocean acidification by adding limestone.

Chemistry - Dissolved Oxygen

Gases dissolve better in cooler liquids; as temperature increases, less gas dissolves.
Warmer temperatures = less dissolved oxygen (DO).
Cooler temperatures = more DO.
As oceans warm, they absorb/store less $\text{CO}_2$ and less DO.
Sediment erosion can warm waters, causing DO to decline.

Chemistry - Ozone Depletion

CFCs are man-made substances in coolants/aerosols.
In the stratosphere, UV light causes one Cl molecule to detach from CFCs.
Free Cl reacts with ozone ( $\text{O}3$ ) to create $\text{O}2$ + ClO, depleting the ozone layer.
Other free O molecules interact with ClO to create $\text{O}_2$ and Cl, repeating the cycle.

Chemistry - Tropospheric Ozone Formation

In the troposphere, $\text{NO}_2$ from cars reacts in sunlight to form NO + O.
The lone oxygen reacts with $\text{O}2$ to form ozone ( $\text{O}3$ ) in the troposphere (bad).
Ozone is "Good up high (stratosphere), bad nearby (troposphere)"
NO reacts with VOCs (Volatile Organic Compounds) to form Photochemical Oxidants.
Photochemical Oxidants combined with Ozone will create Photochemical smog.

Legislation to Know

Clean Air Act: Regulates emissions of pollutants into the air. $\text{CO}_2$ is not regulated.
- Criteria Air Pollutants:
  - N - $\text{NOx}$ - Nitrogen Dioxide (fossil fuel combustion)
  - O - Ozone ( $\text{O}_3$ ) (formed due to NOx breakdown in sunlight)
  - S - $\text{SOx}$ - Sulfur Dioxide (coal combustion)
  - C - CO - Carbon Monoxide (incomplete combustion)
  - L - Lead (formerly in gasoline)
  - P - Particulate Matter (construction and mining)
Clean Water Act: Regulates how water looks and dumping of pollutants into waterways as point pollution.
CITES: Regulates the international trade of endangered species.
CERCLA: Created Superfund account for cleanup costs of contaminated sites; regulates closure and cleanup.
Montreal Protocol: International agreement to phase out CFCs, then HCFCs, to repair the ozone layer.
Kyoto Protocol: International agreement to lower Greenhouse Gas emissions.
Endangered Species Act: US law to protect at-risk species.
Safe Drinking Water Act: Regulates how water tastes and protects drinking water in the USA.

Legislation to Know (Cont.)

Delaney Clause: Banned cancer-causing additives in food (part of the Food, Drug, and Cosmetic Act).
RCRA: Regulates hazardous waste and creates a "cradle to grave" monitoring system; regulates/monitors sanitary landfills.

Top 10 things to review: How electricity is produced

The flow of electrons in a wire
Can be generated from almost any energy source
Energy source spins a turbine
Turbine turns a generator
- Bundle of wires spin around a magnet or vice versa
Spinning causes electrons to move in a wire = electricity

Top 10 Things - Importance of Wetlands

Threatened by drainage and development.
Ecosystem services provided include:
- Maintain drinking water quality
- Flood Control
- Water filtration
- Commercial fisheries
- Recreation
- Wildlife habitat (contributes to food or ecotourism)

Top 10 to review- Air Pollution and Solutions

Need to know diagrams: (a) Natural ozone accumulation, (b) Natural ozone destruction, (c) Buildup of photochemical smog

Top 10 things to review - Air Pollution & Solutions

Primary pollutants
Secondary pollutants
Acid deposition

Air Pollution & Solutions - Solutions

Decreased use of fossil fuels
Improved efficiency
Use of electrostatic precipitators and scrubbers

Top 10 things: Functions, impacts, and solutions of Dams

Advantages and Disadvantages
Need to understand diagram.

Top 10 things: Nitrogen Cycle

Need to understand diagram components:
- Nitrogen in atmosphere ( $\text{N}_2$ )
- Plants
- Assimilation
- Nitrogen-fixing bacteria in root nodules of legumes
- Decomposers (aerobic and anaerobic bacteria and fungi)
- Nitrates ( $\text{NO}_3$ )
- Denitrifying bacteria
- Ammonification
- Nitrogen-fixing soil bacteria
- Ammonium ( $\text{NH}_4$ +)
- Nitrifying bacteria
- Nitrification
- Nitrites ( $\text{NO}_2$ )

Top 10 things: Eutrophication

Need to understand diagram components:
- Dissolved Oxygen
- Biological oxygen demand
- Normal clean water organisms
- Trash fish
- Fish absent. fungi, sludge worms, bacteria

Top 10 things: Eutrophication -Impacts

Level of nitrates discharged from Mississippi River into Gulf of Mexico tripled since 1950s – Causes severe depletion of dissolved oxygen
Food web disruption – Many species cannot migrate away from area and die ▪ Causes deaths of seabird and marine mammal species that depend on dying fish and shellfish
Human factors – Dredging and straightening increases flow of nutrients – Removal of wetlands that act as filters for pollutants

Top 10 things: Eutrophication - Repairs and Prevention

Can only be repaired with:
- Time
- Small areas can be aerated.
Prevented by:
- Education
- Riparian zones
- Plant ground cover or crops to absorb fertilizer
- Sustainable agriculture practices

Top 10 things: Soil Components and Triangle

Horizon = each layer of soil
Soil profile = the cross-section of soil as a whole
Up to six major horizons may occur in a soil profile
-Topsoil = inorganic and organic material most nutritive for plants
-Leaching = dissolved particles move down through horizons

Top 10 things: Soil Texture

Silty soils with medium-size pores, or loamy soils with mixtures of pore sizes are best for plant growth and crop agriculture

Top 10 things: Importance of women in Human Population Growth

Changing role and status of women is key in driving changes to human population growth

Top 10 things to know: Environmental Impacts of Industrial Ag

Need to understand diagram components:
- Energy subsidy

Top 10 things to know: Environmental Impacts of Industrial Ag

Water issues
Air pollution
Land degradation
Loss of biological diversity

Top 10 things to know: Climate Change

Some greenhouse gasses are produced by human activity:
•Burning of fossil fuels
•Agricultural practices
•Deforestation
•Landfills
•Industrial production

Top 10 things to know: Climate Change

Carbon dioxide is a concern…
•Not the most potent greenhouse gas, but it is extremely abundant
-The major contributor to global warming
•Human activities have boosted atmospheric concentrations from 280 parts per million (ppm) to 383 ppm
-To their highest levels in more than 650,000 years

Top 10 things to know: Climate Change

So what are some of the impacts of the increase in greenhouse gases?
•Melting of polar ice caps, Greenland and Antarctica
•Melting of many glaciers around the world
•Melting of permafrost
•Rising of sea levels due to the melting of glaciers and ice sheets and as water warms it expands
•Heat waves
•Cold spells
•Change in precipitation patterns
•Increase in storm intensity
•Shift in ocean currents

Top 10 things to know: Ocean Acidification

Coral reefs can be bleached (right) due to increase in water temperature
Affects coral symbiotes and makes them more susceptible to diseases

Top 10 things to know: Ocean Acidification:

Surface waters have increased acidity by 30% since 1800 –Could reach dangerous levels before 2050
• $\text{CO}2$ combines with water to become carbonic acid ( $\text{H}2\text{CO}_3$ )
–Threatens corals, snails, and other organisms with shells
–Threatens phytoplankton
§Primary producer species of ocean food webs

Top 10 things to know: Climate Change

What about the organisms?
•Organisms are adapted to their environments, so they are affected when those environments change
•Global warming modifies temperature-dependent phenomena
-Timing of migration, breeding
•Spatial shifts in the range of organisms
-Animals and plants will move towards the poles or upward in elevation
-20-30% of all species will be threatened with extinction
•Plants act as carbon sinks; fewer plants means more $\text{CO}_2$ in the atmosphere

Top 10 things to know: Climate Change - Solutions

Slowing Climate Change:

Prevention
Cleanup

Top 10 things to know: Climate Change - Solutions

*Mitigation = pursue actions that reduce greenhouse gas emissions, in order to lessen severity of future climate change
-Renewable energy sources, farm practices to protect soil integrity, preventing deforestation
*Adaptation = accept climate change is happening and pursue strategies to minimize its impacts on us
-Criticized as sidestepping
*Both are necessary

Top 10 things to know: Climate Change - Carbon offset

*Carbon offset = a voluntary payment to another entity intended to enable that entity to reduce the greenhouse emissions that one is unable or unwilling to reduce oneself
-Becoming popular among utilities, businesses, universities, governments, and individuals trying to achieve carbon-neutrality, where no net carbon is emitted
*Carbon offsets fall short
-A lack of oversight to make sure that the offset money accomplishes what it is intended for

Science Practices

Science practices are the anchor for the entire test