Ecosystems are complex networks of living organisms interacting with their... Show more
AP Environmental Science575 views·Updated May 16, 2026·4 pagesAPES Unit 1 Study Guide
V
Vivian Nguyen@ivianguyen_bnxh
1 / 4
1
of 4
Ecosystem Relationships & Biomes
Ever wonder why certain animals live together or why some environments have more plants than others? It all comes down to relationships! An ecosystem is a community where living organisms interact with nonliving components as a system.
Living (biotic) components include producers like plants, and consumers like herbivores, carnivores, and omnivores. Nonliving (abiotic) factors include sunlight, temperature, precipitation, and soil pH. These relationships can be predator-prey (where predator populations follow prey populations over time) or symbiotic (living together). Symbiotic relationships come in three types: mutualism (both benefit), commensalism (one benefits, one unaffected), and parasitism (one benefits, one harmed).
When resources are limited, competition occurs either between different species (interspecific) or within the same species (intraspecific). To reduce competition, species develop resource partitioning - using the same resources in different ways.
Ecosystems are organized from small to large: organism → population → community → ecosystem → biome → biosphere. Terrestrial biomes are characterized by temperature, precipitation, and latitude. Generally, hotter and more humid regions support greater biodiversity and primary productivity.
Remember this! Climate graphs are important tools that show both temperature and precipitation patterns in different biomes - they help explain why certain plants and animals live where they do.
2
of 4
Aquatic Biomes & Carbon Cycle
Water covers most of our planet, creating diverse habitats for life! Aquatic biomes are divided into freshwater (wetlands, streams, rivers, ponds, lakes) and marine (intertidal zones, estuaries, coral reefs, open ocean). Unlike terrestrial biomes that are defined by temperature and precipitation, aquatic biomes are characterized by depth, oxygen levels, light penetration, and nutrient availability.
Wetlands include marshes , swamps (wooded areas), and bogs (acidic areas with sphagnum moss). In oceans, the photic zone receives sunlight allowing photosynthesis, while the aphotic zone is too deep for light to penetrate. Coral reefs and estuaries have high primary productivity and biodiversity because of their nutrient-rich waters.
The carbon cycle moves carbon atoms between different reservoirs on Earth. This biogeochemical cycle is self-regulating but can be disrupted by human activity. Carbon moves through fast cycles (biological processes like photosynthesis and respiration) and slow cycles (geological processes like sedimentation and fossil fuel formation).
During photosynthesis, producers convert carbon dioxide and water to glucose and oxygen. Through respiration, organisms break down glucose to release energy, producing carbon dioxide and water. Decomposition returns carbon to the atmosphere through respiration and to soil through breakdown of organic matter.
Fun fact: The ocean sediment and fossil fuels are Earth's largest carbon reservoirs, storing carbon for millions of years until released by combustion or weathering!
3
of 4
Nitrogen, Phosphorus & Water Cycles
Just like we need nutrients to grow, ecosystems need certain elements to thrive! The nitrogen cycle is crucial because nitrogen is a major component of amino acids (building blocks of proteins) and nucleic acids (building blocks of DNA). Despite making up 78% of our atmosphere, most organisms can't use nitrogen directly from the air.
The cycle involves several key processes: nitrogen fixation (converting N₂ to usable forms via lightning or microbes), ammonification (converting organic nitrogen to ammonia), nitrification (converting ammonia to nitrite then nitrate), assimilation (plants absorbing nitrogen compounds), and denitrification (returning nitrogen to the atmosphere).
The phosphorus cycle differs from other cycles because it's incredibly slow and primarily geological - almost none occurs in the atmosphere. Phosphorus is weathered from rocks, moves through soil and water, and eventually forms sediments again. This limited availability makes phosphorus a limiting factor for ecosystem productivity.
The water cycle is essential to all life and driven by solar energy. Water moves between states (solid, liquid, gas) through processes like evaporation, condensation, precipitation, runoff, and groundwater flow. The ocean serves as the largest water reservoir on Earth.
Important connection: Both nitrogen and phosphorus are common in fertilizers because they enhance plant growth. However, when these nutrients run off into waterways, they can cause harmful algal blooms!
4
of 4
Primary Productivity & Energy Flow
Have you ever wondered how energy moves through an ecosystem? It all starts with primary productivity - the rate at which solar energy is converted into organic compounds through photosynthesis. This forms the foundation of nearly all ecosystems!
We measure productivity in two ways: Gross Primary Productivity (GPP) is the total rate of photosynthesis, while Net Primary Productivity (NPP) is what remains after the producers use some energy for themselves . NPP represents the energy available for consumers in the ecosystem.
Energy transfers through trophic levels - from producers to primary consumers to secondary consumers and beyond. According to the 10% rule, only about 10% of energy transfers from one level to the next. The rest is lost as heat or used for life processes, following the laws of thermodynamics.
A food chain shows a single pathway of energy through an ecosystem, while a food web shows interconnected chains that more accurately represent the complexity of real ecosystems. These models help us understand how energy flows and how disruptions to one species can affect many others.
Why this matters: The 10% energy transfer rule explains why there are always fewer carnivores than herbivores in a balanced ecosystem - and why eating lower on the food chain is more energy-efficient!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Similar Content
Most popular content in AP Environmental Science
9I
AP Environmental ScienceIntroduction to Ecological Economics
Explore the fundamental principles of ecological economics, including natural capital, ecosystem services, and the valuation of natural resources.
9th4260
AP Environmental ScienceAPES Final Notes
Notes of the high weighted units of APES. Watch Jordan Smedes' videos on youtube and use these notes to review for the AP test.
1,096120
AP Environmental ScienceUnit 1 Multiple Choice Test
APES Unit 1 MC test from AP Central. 33 questions with diagrams.
1,80121
AP Environmental ScienceAPES UNIT 1
Unit 1 APES notes
11th650
AP Environmental ScienceAPES Sustainability, Biomes, Evolution Review Notes
Chapter 1, 2, 4, 5, 6 Notes REVIEWED
38010
AP Environmental ScienceAPES Unit 2 Key Terms
Unit 2 key terms for APES- biospheres
11th380
AP Environmental ScienceAPES Unit One and Two
brief overview with what you should know for unit 1 and 2 with definitions and examples included.
11th1747
AP Environmental ScienceAPES Unit 3.4 Carrying Capacity
For Unit 3.4 of AP Environmental Science, discusses carrying capacity.
1487
AP Environmental ScienceBIOGEOCHEMICAL CYCLES
Gives an overview about chemical elements and movement of elements.
1348
Most popular content
9O
AP US HistoryOrigins and Dynamics of the Columbian Exchange
Analyze the ecological and economic motivations behind the initial transfer of goods, people, and diseases between the Old and New Worlds.
9th3,1280
I
AP US HistoryIntroduction to Early Cultural Interactions
Analyze the initial social and religious encounters between Europeans, Africans, and Indigenous peoples in the colonial Americas.
9th2,7730
O
AP World HistoryOrigins of Ancient River Civilizations
Analyze the environmental factors and technological innovations that led to the rise of early states in Mesopotamia, Egypt, and the Indus Valley.
9th3,1860
M
AP US HistoryMotivations for European Exploration
Analyze the economic, religious, and political factors that drove European powers to the Americas during the 15th and 16th centuries.
9th1,7780
F
AP PsychologyFoundations of Ethical Guidelines in Research
Practice the core principles of the APA ethical code including informed consent, debriefing, and the role of Institutional Review Boards.
9th1,3360
I
AP US HistoryIntroduction to Native American Societies
Examine the diverse social, political, and economic structures of North American indigenous groups prior to European contact.
9th1,1100
I
AP BiologyIntroduction to Biological Elements of Life
Practice identifying the essential elements including carbon, nitrogen, phosphorus, and sulfur that compose biological macromolecules.
9th1,7360
I
AP US HistoryIntroduction to the Spanish Encomienda System
Explore the fundamental economic and social structures of the Spanish colonial system, focusing on the encomienda and the casta social hierarchy.
9th8890
O
AP World HistoryOrigins and Continuity of the Byzantine Empire
Analyze the political and cultural transitions from the Roman Empire to the Byzantine Empire, focusing on the reign of Justinian I and his code.
9th1,6320
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user
AP Environmental Science575 views·Updated May 16, 2026·4 pagesAPES Unit 1 Study Guide
V
Vivian Nguyen@ivianguyen_bnxh
Ecosystems are complex networks of living organisms interacting with their environment. This unit explores how different species interact, how energy flows through ecosystems, and the cycling of essential elements that sustain life on Earth. Understanding these connections helps us see... Show more
1
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Ecosystem Relationships & Biomes
Ever wonder why certain animals live together or why some environments have more plants than others? It all comes down to relationships! An ecosystem is a community where living organisms interact with nonliving components as a system.
Living (biotic) components include producers like plants, and consumers like herbivores, carnivores, and omnivores. Nonliving (abiotic) factors include sunlight, temperature, precipitation, and soil pH. These relationships can be predator-prey (where predator populations follow prey populations over time) or symbiotic (living together). Symbiotic relationships come in three types: mutualism (both benefit), commensalism (one benefits, one unaffected), and parasitism (one benefits, one harmed).
When resources are limited, competition occurs either between different species (interspecific) or within the same species (intraspecific). To reduce competition, species develop resource partitioning - using the same resources in different ways.
Ecosystems are organized from small to large: organism → population → community → ecosystem → biome → biosphere. Terrestrial biomes are characterized by temperature, precipitation, and latitude. Generally, hotter and more humid regions support greater biodiversity and primary productivity.
Remember this! Climate graphs are important tools that show both temperature and precipitation patterns in different biomes - they help explain why certain plants and animals live where they do.
2
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Aquatic Biomes & Carbon Cycle
Water covers most of our planet, creating diverse habitats for life! Aquatic biomes are divided into freshwater (wetlands, streams, rivers, ponds, lakes) and marine (intertidal zones, estuaries, coral reefs, open ocean). Unlike terrestrial biomes that are defined by temperature and precipitation, aquatic biomes are characterized by depth, oxygen levels, light penetration, and nutrient availability.
Wetlands include marshes , swamps (wooded areas), and bogs (acidic areas with sphagnum moss). In oceans, the photic zone receives sunlight allowing photosynthesis, while the aphotic zone is too deep for light to penetrate. Coral reefs and estuaries have high primary productivity and biodiversity because of their nutrient-rich waters.
The carbon cycle moves carbon atoms between different reservoirs on Earth. This biogeochemical cycle is self-regulating but can be disrupted by human activity. Carbon moves through fast cycles (biological processes like photosynthesis and respiration) and slow cycles (geological processes like sedimentation and fossil fuel formation).
During photosynthesis, producers convert carbon dioxide and water to glucose and oxygen. Through respiration, organisms break down glucose to release energy, producing carbon dioxide and water. Decomposition returns carbon to the atmosphere through respiration and to soil through breakdown of organic matter.
Fun fact: The ocean sediment and fossil fuels are Earth's largest carbon reservoirs, storing carbon for millions of years until released by combustion or weathering!
3
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Nitrogen, Phosphorus & Water Cycles
Just like we need nutrients to grow, ecosystems need certain elements to thrive! The nitrogen cycle is crucial because nitrogen is a major component of amino acids (building blocks of proteins) and nucleic acids (building blocks of DNA). Despite making up 78% of our atmosphere, most organisms can't use nitrogen directly from the air.
The cycle involves several key processes: nitrogen fixation (converting N₂ to usable forms via lightning or microbes), ammonification (converting organic nitrogen to ammonia), nitrification (converting ammonia to nitrite then nitrate), assimilation (plants absorbing nitrogen compounds), and denitrification (returning nitrogen to the atmosphere).
The phosphorus cycle differs from other cycles because it's incredibly slow and primarily geological - almost none occurs in the atmosphere. Phosphorus is weathered from rocks, moves through soil and water, and eventually forms sediments again. This limited availability makes phosphorus a limiting factor for ecosystem productivity.
The water cycle is essential to all life and driven by solar energy. Water moves between states (solid, liquid, gas) through processes like evaporation, condensation, precipitation, runoff, and groundwater flow. The ocean serves as the largest water reservoir on Earth.
Important connection: Both nitrogen and phosphorus are common in fertilizers because they enhance plant growth. However, when these nutrients run off into waterways, they can cause harmful algal blooms!
4
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Primary Productivity & Energy Flow
Have you ever wondered how energy moves through an ecosystem? It all starts with primary productivity - the rate at which solar energy is converted into organic compounds through photosynthesis. This forms the foundation of nearly all ecosystems!
We measure productivity in two ways: Gross Primary Productivity (GPP) is the total rate of photosynthesis, while Net Primary Productivity (NPP) is what remains after the producers use some energy for themselves . NPP represents the energy available for consumers in the ecosystem.
Energy transfers through trophic levels - from producers to primary consumers to secondary consumers and beyond. According to the 10% rule, only about 10% of energy transfers from one level to the next. The rest is lost as heat or used for life processes, following the laws of thermodynamics.
A food chain shows a single pathway of energy through an ecosystem, while a food web shows interconnected chains that more accurately represent the complexity of real ecosystems. These models help us understand how energy flows and how disruptions to one species can affect many others.
Why this matters: The 10% energy transfer rule explains why there are always fewer carnivores than herbivores in a balanced ecosystem - and why eating lower on the food chain is more energy-efficient!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Similar Content
Most popular content in AP Environmental Science
9I
AP Environmental ScienceIntroduction to Ecological Economics
Explore the fundamental principles of ecological economics, including natural capital, ecosystem services, and the valuation of natural resources.
9th4260
AP Environmental ScienceAPES Final Notes
Notes of the high weighted units of APES. Watch Jordan Smedes' videos on youtube and use these notes to review for the AP test.
1,096120
AP Environmental ScienceUnit 1 Multiple Choice Test
APES Unit 1 MC test from AP Central. 33 questions with diagrams.
1,80121
AP Environmental ScienceAPES UNIT 1
Unit 1 APES notes
11th650
AP Environmental ScienceAPES Sustainability, Biomes, Evolution Review Notes
Chapter 1, 2, 4, 5, 6 Notes REVIEWED
38010
AP Environmental ScienceAPES Unit 2 Key Terms
Unit 2 key terms for APES- biospheres
11th380
AP Environmental ScienceAPES Unit One and Two
brief overview with what you should know for unit 1 and 2 with definitions and examples included.
11th1747
AP Environmental ScienceAPES Unit 3.4 Carrying Capacity
For Unit 3.4 of AP Environmental Science, discusses carrying capacity.
1487
AP Environmental ScienceBIOGEOCHEMICAL CYCLES
Gives an overview about chemical elements and movement of elements.
1348
Most popular content
9O
AP US HistoryOrigins and Dynamics of the Columbian Exchange
Analyze the ecological and economic motivations behind the initial transfer of goods, people, and diseases between the Old and New Worlds.
9th3,1280
I
AP US HistoryIntroduction to Early Cultural Interactions
Analyze the initial social and religious encounters between Europeans, Africans, and Indigenous peoples in the colonial Americas.
9th2,7730
O
AP World HistoryOrigins of Ancient River Civilizations
Analyze the environmental factors and technological innovations that led to the rise of early states in Mesopotamia, Egypt, and the Indus Valley.
9th3,1860
M
AP US HistoryMotivations for European Exploration
Analyze the economic, religious, and political factors that drove European powers to the Americas during the 15th and 16th centuries.
9th1,7780
F
AP PsychologyFoundations of Ethical Guidelines in Research
Practice the core principles of the APA ethical code including informed consent, debriefing, and the role of Institutional Review Boards.
9th1,3360
I
AP US HistoryIntroduction to Native American Societies
Examine the diverse social, political, and economic structures of North American indigenous groups prior to European contact.
9th1,1100
I
AP BiologyIntroduction to Biological Elements of Life
Practice identifying the essential elements including carbon, nitrogen, phosphorus, and sulfur that compose biological macromolecules.
9th1,7360
I
AP US HistoryIntroduction to the Spanish Encomienda System
Explore the fundamental economic and social structures of the Spanish colonial system, focusing on the encomienda and the casta social hierarchy.
9th8890
O
AP World HistoryOrigins and Continuity of the Byzantine Empire
Analyze the political and cultural transitions from the Roman Empire to the Byzantine Empire, focusing on the reign of Justinian I and his code.
9th1,6320
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user