Biology
Chemistry
AP Chemistry
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AP English Literature
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Dec 4, 2025
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skoot
@skoot
Earth's diverse aquatic environments and biological systems form the foundation... Show more
Water covers a massive 71% of Earth's surface, creating vast habitats for countless organisms. In these aquatic environments, key factors like temperature, dissolved oxygen, light penetration, and nutrient availability determine which creatures can thrive.
The distribution of aquatic life is largely determined by salinity (salt content). Saltwater environments make up 98% of Earth's water, with 96.5% found in oceans. These marine zones include vibrant coral reefs (home to 90% of fish species), productive estuaries (where rivers meet oceans creating brackish water), and mangrove forests with deep roots that prevent coastal erosion.
Aquatic species fall into several categories: nekton (strong swimmers like fish and whales), benthos (bottom dwellers such as crabs and clams), decomposers (mainly bacteria), and phytoplankton (primary producers that form the base of marine food webs).
Did you know? About 90% of marine fish species stay near coastlines where nutrients are abundant, rather than venturing into the open ocean!
Oceans are divided into distinctive zones, each supporting different life forms. The nutrient-rich coastal zone extends from land to the edge of the continental shelf and hosts 90% of all marine species. Beyond lies the open sea and ocean bottom, which have three primary layers.
These layers include the sunlit euphotic zone (home to phytoplankton and large fish), the dimly lit bathyal zone (where zooplankton and smaller fish live), and the dark, cold abyssal zone (with no plants, only filter feeders).
Freshwater makes up only 2.5% of Earth's water (mostly in ice caps) but creates diverse habitats. Lakes have four distinct zones: the shallow, sunny littoral zone near shore; the sunlit limnetic zone in upper waters; the low-oxygen profundal zone in middle depths; and the benthic zone at the bottom where decomposers process dead matter.
Remember this: The deepest ocean zones receive no sunlight at all, yet still support unique life forms adapted to extreme pressure, cold, and darkness!
Biological diversity takes many forms that scientists categorize and study. Species diversity includes both the variety of species (richness) and how evenly they're distributed. Genetic diversity refers to the variety of genes within populations, while ecosystem diversity encompasses the range of habitats and ecological communities.
Earth's major biomes are regions with distinct climates and species. These include deserts (low precipitation, often hot), grasslands, tropical rainforests, temperate regions, and Arctic environments. Scientists use climatographs to represent and study the climate patterns in different biomes.
Special biome types include the chaparral (a shrubland found on every continent with hot, dry summers) and the tundra with its permanently frozen soil called permafrost.
Quick tip: When studying biomes for a test, focus on both the climate conditions AND the typical plant adaptations for each—they go hand in hand!
The intertidal zone is a fascinating biome found along shorelines where land meets sea. This ecosystem experiences dramatic changes as tides move in and out throughout the day.
During low tide, organisms are exposed to air and must withstand drying out, temperature fluctuations, and predators from land. When high tide returns, these same creatures become submerged in water and face marine predators instead.
Because of these constantly shifting conditions, intertidal organisms like starfish are considered extremophiles—creatures adapted to survive in environments that would kill most other species.
Amazing fact: Some intertidal creatures can survive being baked in the sun for hours during low tide, then completely submerged in cold saltwater during high tide—all in the same day!
The hydrologic cycle continuously collects, purifies, and distributes Earth's water. Part of this cycle includes transpiration, where trees release water vapor back into the atmosphere.
The carbon cycle circulates this crucial element that forms the building blocks of all life. Carbon moves between sources (like burning fossil fuels, respiration, and deforestation) and sinks (the atmosphere, oceans, forests, and limestone).
The nitrogen cycle is essential for plant nutrition but faces a challenge: atmospheric nitrogen must be "fixed" before organisms can use it. This process includes nitrogen fixation (by lightning or bacteria), nitrification, assimilation by plants, and eventually denitrification that returns nitrogen to the atmosphere.
The phosphorus cycle moves more slowly than other cycles, making phosphorus a limited nutrient. With no atmospheric component, phosphorus is stored in rocks and cycles through living organisms and soil. This cycle is critical for plant growth but operates at a much slower pace than other nutrient cycles.
Important connection: Human activities have dramatically accelerated the carbon cycle through fossil fuel use and deforestation, leading to climate change concerns.
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.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
App Store
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 THE SCHOOLGPT. 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 THE SCHOOLGPT. 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
skoot
@skoot
Earth's diverse aquatic environments and biological systems form the foundation of our planet's ecological balance. These interconnected biomes and cycles support an incredible variety of life and maintain crucial environmental processes that sustain all living things.
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Water covers a massive 71% of Earth's surface, creating vast habitats for countless organisms. In these aquatic environments, key factors like temperature, dissolved oxygen, light penetration, and nutrient availability determine which creatures can thrive.
The distribution of aquatic life is largely determined by salinity (salt content). Saltwater environments make up 98% of Earth's water, with 96.5% found in oceans. These marine zones include vibrant coral reefs (home to 90% of fish species), productive estuaries (where rivers meet oceans creating brackish water), and mangrove forests with deep roots that prevent coastal erosion.
Aquatic species fall into several categories: nekton (strong swimmers like fish and whales), benthos (bottom dwellers such as crabs and clams), decomposers (mainly bacteria), and phytoplankton (primary producers that form the base of marine food webs).
Did you know? About 90% of marine fish species stay near coastlines where nutrients are abundant, rather than venturing into the open ocean!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Oceans are divided into distinctive zones, each supporting different life forms. The nutrient-rich coastal zone extends from land to the edge of the continental shelf and hosts 90% of all marine species. Beyond lies the open sea and ocean bottom, which have three primary layers.
These layers include the sunlit euphotic zone (home to phytoplankton and large fish), the dimly lit bathyal zone (where zooplankton and smaller fish live), and the dark, cold abyssal zone (with no plants, only filter feeders).
Freshwater makes up only 2.5% of Earth's water (mostly in ice caps) but creates diverse habitats. Lakes have four distinct zones: the shallow, sunny littoral zone near shore; the sunlit limnetic zone in upper waters; the low-oxygen profundal zone in middle depths; and the benthic zone at the bottom where decomposers process dead matter.
Remember this: The deepest ocean zones receive no sunlight at all, yet still support unique life forms adapted to extreme pressure, cold, and darkness!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Biological diversity takes many forms that scientists categorize and study. Species diversity includes both the variety of species (richness) and how evenly they're distributed. Genetic diversity refers to the variety of genes within populations, while ecosystem diversity encompasses the range of habitats and ecological communities.
Earth's major biomes are regions with distinct climates and species. These include deserts (low precipitation, often hot), grasslands, tropical rainforests, temperate regions, and Arctic environments. Scientists use climatographs to represent and study the climate patterns in different biomes.
Special biome types include the chaparral (a shrubland found on every continent with hot, dry summers) and the tundra with its permanently frozen soil called permafrost.
Quick tip: When studying biomes for a test, focus on both the climate conditions AND the typical plant adaptations for each—they go hand in hand!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The intertidal zone is a fascinating biome found along shorelines where land meets sea. This ecosystem experiences dramatic changes as tides move in and out throughout the day.
During low tide, organisms are exposed to air and must withstand drying out, temperature fluctuations, and predators from land. When high tide returns, these same creatures become submerged in water and face marine predators instead.
Because of these constantly shifting conditions, intertidal organisms like starfish are considered extremophiles—creatures adapted to survive in environments that would kill most other species.
Amazing fact: Some intertidal creatures can survive being baked in the sun for hours during low tide, then completely submerged in cold saltwater during high tide—all in the same day!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The hydrologic cycle continuously collects, purifies, and distributes Earth's water. Part of this cycle includes transpiration, where trees release water vapor back into the atmosphere.
The carbon cycle circulates this crucial element that forms the building blocks of all life. Carbon moves between sources (like burning fossil fuels, respiration, and deforestation) and sinks (the atmosphere, oceans, forests, and limestone).
The nitrogen cycle is essential for plant nutrition but faces a challenge: atmospheric nitrogen must be "fixed" before organisms can use it. This process includes nitrogen fixation (by lightning or bacteria), nitrification, assimilation by plants, and eventually denitrification that returns nitrogen to the atmosphere.
The phosphorus cycle moves more slowly than other cycles, making phosphorus a limited nutrient. With no atmospheric component, phosphorus is stored in rocks and cycles through living organisms and soil. This cycle is critical for plant growth but operates at a much slower pace than other nutrient cycles.
Important connection: Human activities have dramatically accelerated the carbon cycle through fossil fuel use and deforestation, leading to climate change concerns.
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.
You can download the app in the Google Play Store and in the Apple App Store.
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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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 THE SCHOOLGPT. 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 THE SCHOOLGPT. 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
