Subjects
Maths
Chemistry
Biology
English Language
History
Responding to change (a2 only)
Infection and response
Homeostasis and response
Energy transfers (a2 only)
Cell biology
Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
Organisation
Substance exchange
Bioenergetics
Genetic information & variation
Inheritance, variation and evolution
Genetics & ecosystems (a2 only)
Ecology
Cells
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Britain & the wider world: 1745 -1901
1l the quest for political stability: germany, 1871-1991
The cold war
Inter-war germany
Medieval period: 1066 -1509
2d religious conflict and the church in england, c1529-c1570
2o democracy and nazism: germany, 1918-1945
1f industrialisation and the people: britain, c1783-1885
1c the tudors: england, 1485-1603
2m wars and welfare: britain in transition, 1906-1957
World war two & the holocaust
2n revolution and dictatorship: russia, 1917-1953
2s the making of modern britain, 1951-2007
World war one
Britain: 1509 -1745
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Geography
2 Dec 2025
818
4 pages
Tropical rainforests and polar environments are two of Earth's most extreme biomes, each with incredible adaptations that help... Show more
Ever wondered how rainforests pack so much life into relatively small spaces? These incredible ecosystems are like nature's skyscrapers, with distinct layers called stratification that maximise every bit of space and sunlight.
The structure goes from emergent trees at the top, down through the canopy layer, then the undercanopy (where lianas climb towards sunlight), and finally the shrub layer at ground level. This clever design means different species can thrive at different heights without competing directly.
What's brilliant about rainforest soils is how they work - they're actually quite infertile underneath, but decomposition happens so quickly that there's always a fertile top layer. The rapid nutrient cycle means plants can grow incredibly fast, with emergent trees storing nutrients and dropping leaves as litter that quickly turns to humus.
Key Insight Trees don't just grow here - they actively help create the conditions for more growth by intercepting rain and stabilising soil with their roots.
Plants and animals have developed some seriously clever tricks to survive in rainforests. Trees grow tall and straight to reach sunlight, with buttress roots providing stability in shallow soil. Drip-tip leaves let rain slide off easily, and some can even swivel to track the sun.
Animals are equally smart - many are nocturnal to reduce competition, whilst jaguars use camouflage with spots that mimic dappled sunlight. Jaguars can also swim across rivers, chimps have strong limbs for swinging through canopies, and toucans have perfectly balanced feet for gripping branches.
Unfortunately, deforestation threatens these amazing ecosystems through farming (plantations and cattle ranches), mining for iron and copper, logging for timber, road building (over 12,000km of roads cut through rainforests), and damming rivers for hydroelectric power.
Remember Rainforests are carbon sinks, oxygen producers, soil protectors, climate regulators, and sources of countless resources - losing them affects the entire planet.
Smart sustainable management focuses on income that doesn't require tree removal. Ecotourism brings money whilst protecting forests, selective logging replants trees, and governments can reduce demand for hardwood. The 2017 UN REDD programme actually rewards countries for using rainforests sustainably.
Polar environments are completely different but equally fascinating. The South Pole averages -60°C in winter and receives only 166mm of rainfall yearly because cold air can't hold much moisture. Penguins live at the South Pole, polar bears at the North Pole.
Tundra environments have short, cool summers with 24-hour darkness in winter and constant light in summer. Only the top active layer of ground thaws in summer, allowing plants to grow. This biome has the lowest species diversity, with lichens, mosses, and shrubs staying low and rounded to protect against wind.
Fascinating Fact Permafrost locks up methane and provides high albedo (reflectivity), helping regulate Earth's climate.
Cold environments face threats from indigenous cultural erosion due to tourism, and industry interest in oil, iron ore, copper, and platinum reserves that become more accessible as ice shrinks. The Antarctic Treaty signed in 1961 helps protect these fragile regions.
Smart management includes building homes on stilts so heat doesn't warm the ground, WWF's 1995 code of conduct for Arctic tourism, and international cooperation through treaties.
Rainforest interdependence shows how connected these ecosystems really are. For example, agouti (rodents) are practically the only animals that can crack open hard Brazil nut seed pods. They bury some nuts for later, which helps them germinate - meaning these little rodents are essential for Brazil nut tree survival.
Think About It Every species in these environments depends on others - remove one, and the whole system can collapse.
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and 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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Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Quotes from every main character
English LiteratureApp 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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Tropical rainforests and polar environments are two of Earth's most extreme biomes, each with incredible adaptations that help plants and animals survive. Despite covering only 7% of the world's surface, rainforests contain two-thirds of all plant species, whilst polar regions... Show more
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Ever wondered how rainforests pack so much life into relatively small spaces? These incredible ecosystems are like nature's skyscrapers, with distinct layers called stratification that maximise every bit of space and sunlight.
The structure goes from emergent trees at the top, down through the canopy layer, then the undercanopy (where lianas climb towards sunlight), and finally the shrub layer at ground level. This clever design means different species can thrive at different heights without competing directly.
What's brilliant about rainforest soils is how they work - they're actually quite infertile underneath, but decomposition happens so quickly that there's always a fertile top layer. The rapid nutrient cycle means plants can grow incredibly fast, with emergent trees storing nutrients and dropping leaves as litter that quickly turns to humus.
Key Insight: Trees don't just grow here - they actively help create the conditions for more growth by intercepting rain and stabilising soil with their roots.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Plants and animals have developed some seriously clever tricks to survive in rainforests. Trees grow tall and straight to reach sunlight, with buttress roots providing stability in shallow soil. Drip-tip leaves let rain slide off easily, and some can even swivel to track the sun.
Animals are equally smart - many are nocturnal to reduce competition, whilst jaguars use camouflage with spots that mimic dappled sunlight. Jaguars can also swim across rivers, chimps have strong limbs for swinging through canopies, and toucans have perfectly balanced feet for gripping branches.
Unfortunately, deforestation threatens these amazing ecosystems through farming (plantations and cattle ranches), mining for iron and copper, logging for timber, road building (over 12,000km of roads cut through rainforests), and damming rivers for hydroelectric power.
Remember: Rainforests are carbon sinks, oxygen producers, soil protectors, climate regulators, and sources of countless resources - losing them affects the entire planet.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Smart sustainable management focuses on income that doesn't require tree removal. Ecotourism brings money whilst protecting forests, selective logging replants trees, and governments can reduce demand for hardwood. The 2017 UN REDD programme actually rewards countries for using rainforests sustainably.
Polar environments are completely different but equally fascinating. The South Pole averages -60°C in winter and receives only 166mm of rainfall yearly because cold air can't hold much moisture. Penguins live at the South Pole, polar bears at the North Pole.
Tundra environments have short, cool summers with 24-hour darkness in winter and constant light in summer. Only the top active layer of ground thaws in summer, allowing plants to grow. This biome has the lowest species diversity, with lichens, mosses, and shrubs staying low and rounded to protect against wind.
Fascinating Fact: Permafrost locks up methane and provides high albedo (reflectivity), helping regulate Earth's climate.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Cold environments face threats from indigenous cultural erosion due to tourism, and industry interest in oil, iron ore, copper, and platinum reserves that become more accessible as ice shrinks. The Antarctic Treaty signed in 1961 helps protect these fragile regions.
Smart management includes building homes on stilts so heat doesn't warm the ground, WWF's 1995 code of conduct for Arctic tourism, and international cooperation through treaties.
Rainforest interdependence shows how connected these ecosystems really are. For example, agouti (rodents) are practically the only animals that can crack open hard Brazil nut seed pods. They bury some nuts for later, which helps them germinate - meaning these little rodents are essential for Brazil nut tree survival.
Think About It: Every species in these environments depends on others - remove one, and the whole system can collapse.
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
5
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Quotes from every main character
English LiteratureApp 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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Sociology