Environmental science explores how living organisms interact with their environment... Show more
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Updated Feb 25, 2026
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Comprehensive APES Study Notes: Sustainability, Biomes, and Evolution Exam Prep
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Environmental Science Fundamentals
Ever wonder why environmental issues are so complex? It's because everything in nature is connected. Environmental science studies these connections and how humans impact Earth's systems. We depend on solar capital (energy from the sun) and natural capital (resources) to survive.
Our world faces challenges from exponential growth in population, resource use, and waste production. These factors contribute to what scientists call the "Big Five" environmental problems: biodiversity loss, air pollution, water pollution, waste production, and food supply concerns. These issues stem from population growth, wasteful resource use, poverty, poor environmental accounting, and ecological ignorance.
Resources can be renewable (replenished within a human lifespan), nonrenewable (fixed quantities that take millions of years to form), or perpetual (continuously renewed). Using renewable resources beyond their sustainable yield leads to environmental degradation, like what happens in the Tragedy of the Commons when shared resources are overused.
Think About It: Your ecological footprint represents your environmental impact. How might your daily choices affect this footprint?
Different worldviews shape how we approach environmental problems. The planetary management worldview sees humans as most important, while the stewardship worldview emphasizes our responsibility to care for nature. The environmental wisdom worldview recognizes that nature exists for all species and promotes sustainable growth.
Ecological Systems and Cycles
Ecology isn't just about plants and animals—it's about the web of relationships that sustains all life. This web includes individual organisms, populations (groups of the same species), communities (different species living together), and ecosystems (communities interacting with their environment).
Earth's life-support systems include the atmosphere (air), hydrosphere (water), lithosphere (soil and crust), and biosphere (where all life exists). These systems work together through energy flow and nutrient cycling. Remember that energy flows one-way—high-quality solar energy enters ecosystems and exits as low-quality heat—while matter cycles continuously.
The law of tolerance explains why species live where they do—physical and chemical factors must be within tolerable ranges. The limiting factor principle shows how too much or too little of something can prevent population growth. These principles determine which areas have high or low primary productivity—the rate at which producers create biomass from sunlight.
Important Concept: Biogeochemical cycles move nutrients through ecosystems. Human activities are disrupting these cycles by adding excess carbon to the atmosphere, nitrogen to soil and water, and phosphorus to aquatic systems.
Long-term sustainability depends on two key principles: using renewable solar energy and recycling chemical nutrients. When we disrupt these cycles—by burning fossil fuels or adding too many fertilizers—we threaten the stability of our environmental systems.
Biodiversity and Climate Systems
Earth's perfect conditions for life didn't happen by accident. Our planet's distance from the sun, liquid water, rotation speed, and size all create the ideal environment for living things to thrive. This environment supports the processes of evolution and biodiversity.
Microevolution happens when genetic mutations and natural selection lead to changes in populations over time. When species interact and influence each other's evolution, we call it coevolution. Each species occupies an ecological niche—its functional role in an ecosystem. The fundamental niche represents all conditions a species could potentially use, while its realized niche shows what it actually uses when competing with other species.
Biodiversity emerges from the balance between speciation (the formation of new species) and extinction. While background extinction naturally occurs at a rate of 1-5 species per million years, human activities are accelerating extinction to concerning levels.
Real-World Connection: Think about climate systems as Earth's thermostat. They determine which plants and animals can survive in different regions by controlling temperature and precipitation patterns.
Biomes are large regions with characteristic climates and dominant species. From deserts to grasslands to forests, each biome has adapted to specific conditions. Deserts feature plants that conserve water, grasslands support grazing animals, and forests create complex, layered ecosystems. Mountains serve as biodiversity hotspots and water storehouses, playing a crucial role in regulating Earth's climate.
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Most popular content: Human Impacts on the Environment
Most popular content in AP Environmental Science
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5
App Store
4.7/5
Google 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 S
iOS 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 Klich
Android 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.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
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 S
iOS 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 Klich
Android 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.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Comprehensive APES Study Notes: Sustainability, Biomes, and Evolution Exam Prep
Environmental science explores how living organisms interact with their environment and how we can solve environmental challenges. This field combines physical and social sciences to understand Earth's systems and our impact on them. Let's break down key ecological concepts and... Show more
Environmental Science Fundamentals
Ever wonder why environmental issues are so complex? It's because everything in nature is connected. Environmental science studies these connections and how humans impact Earth's systems. We depend on solar capital (energy from the sun) and natural capital (resources) to survive.
Our world faces challenges from exponential growth in population, resource use, and waste production. These factors contribute to what scientists call the "Big Five" environmental problems: biodiversity loss, air pollution, water pollution, waste production, and food supply concerns. These issues stem from population growth, wasteful resource use, poverty, poor environmental accounting, and ecological ignorance.
Resources can be renewable (replenished within a human lifespan), nonrenewable (fixed quantities that take millions of years to form), or perpetual (continuously renewed). Using renewable resources beyond their sustainable yield leads to environmental degradation, like what happens in the Tragedy of the Commons when shared resources are overused.
Think About It: Your ecological footprint represents your environmental impact. How might your daily choices affect this footprint?
Different worldviews shape how we approach environmental problems. The planetary management worldview sees humans as most important, while the stewardship worldview emphasizes our responsibility to care for nature. The environmental wisdom worldview recognizes that nature exists for all species and promotes sustainable growth.
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Ecological Systems and Cycles
Ecology isn't just about plants and animals—it's about the web of relationships that sustains all life. This web includes individual organisms, populations (groups of the same species), communities (different species living together), and ecosystems (communities interacting with their environment).
Earth's life-support systems include the atmosphere (air), hydrosphere (water), lithosphere (soil and crust), and biosphere (where all life exists). These systems work together through energy flow and nutrient cycling. Remember that energy flows one-way—high-quality solar energy enters ecosystems and exits as low-quality heat—while matter cycles continuously.
The law of tolerance explains why species live where they do—physical and chemical factors must be within tolerable ranges. The limiting factor principle shows how too much or too little of something can prevent population growth. These principles determine which areas have high or low primary productivity—the rate at which producers create biomass from sunlight.
Important Concept: Biogeochemical cycles move nutrients through ecosystems. Human activities are disrupting these cycles by adding excess carbon to the atmosphere, nitrogen to soil and water, and phosphorus to aquatic systems.
Long-term sustainability depends on two key principles: using renewable solar energy and recycling chemical nutrients. When we disrupt these cycles—by burning fossil fuels or adding too many fertilizers—we threaten the stability of our environmental systems.
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Biodiversity and Climate Systems
Earth's perfect conditions for life didn't happen by accident. Our planet's distance from the sun, liquid water, rotation speed, and size all create the ideal environment for living things to thrive. This environment supports the processes of evolution and biodiversity.
Microevolution happens when genetic mutations and natural selection lead to changes in populations over time. When species interact and influence each other's evolution, we call it coevolution. Each species occupies an ecological niche—its functional role in an ecosystem. The fundamental niche represents all conditions a species could potentially use, while its realized niche shows what it actually uses when competing with other species.
Biodiversity emerges from the balance between speciation (the formation of new species) and extinction. While background extinction naturally occurs at a rate of 1-5 species per million years, human activities are accelerating extinction to concerning levels.
Real-World Connection: Think about climate systems as Earth's thermostat. They determine which plants and animals can survive in different regions by controlling temperature and precipitation patterns.
Biomes are large regions with characteristic climates and dominant species. From deserts to grasslands to forests, each biome has adapted to specific conditions. Deserts feature plants that conserve water, grasslands support grazing animals, and forests create complex, layered ecosystems. Mountains serve as biodiversity hotspots and water storehouses, playing a crucial role in regulating Earth's climate.
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.
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Most popular content: Human Impacts on the Environment
Most popular content in AP Environmental Science
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5
App Store
4.7/5
Google 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 S
iOS 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 Klich
Android 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.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
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 S
iOS 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 Klich
Android 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.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user