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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Biology
5 Dec 2025
339
2 pages
Kat bert @katbert
Understanding biochemistry is like having a toolkit for analysing life itself - these fundamental tests and molecular structures... Show more
You'll need to master four key biochemical tests for your exams. Starch turns blue-black with iodine solution, whilst proteins change from blue to purple with biuret reagent. For lipids, mix with ethanol then water - a cloudy emulsion means lipids are present.
Reducing sugars create a colour spectrum with Benedict's reagent, from blue (no sugar) through green, yellow, orange to brick-red (loads of sugar). Non-reducing sugars need boiling with hydrochloric acid first to break them down.
Water's unique properties make life possible. Its high surface tension creates habitats, whilst high specific heat capacity keeps cellular conditions stable. The fact that ice floats protects aquatic life underneath, and water's cohesive properties allow it to be pulled up through plant stems.
Quick Tip Remember the acronym CHILIS for water properties - Colourless, High surface tension, High latent heat, High specific heat, Ice floats, Liquid at room temp, Strong cohesion!
Protein structure has four levels you must understand. Primary structure is simply the amino acid sequence, whilst secondary structure involves hydrogen bonding creating repeating patterns like alpha-helices. Tertiary structure gives the final 3D shape through various bonds and interactions.
Globular proteins fold into spherical shapes and dissolve in water (like haemoglobin), whereas fibrous proteins remain long and parallel, usually insoluble (like collagen). Quaternary structure involves multiple polypeptide chains working together.
Lipids serve three main functions insulation, energy storage, and protection. Triglycerides combine glycerol with three fatty acids, whilst phospholipids have just two fatty acids plus a phosphate group, creating molecules with hydrophilic heads and hydrophobic tails.
Exam Focus Van der Waals forces occur because electrons move constantly, creating temporary positive and negative areas that help molecules stick together - this often appears in extended response questions!
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
Explore the structure and function of carbohydrates, focusing on monosaccharides and disaccharides. This summary covers key concepts such as glycosidic bonds, condensation and hydrolysis reactions, and the properties of glucose, galactose, and fructose. Ideal for OCR A Level Biology students.
BiologyExplore the essential components of biological molecules in this concise revision guide. Understand the structure, functions, and examples of carbohydrates, proteins, lipids, and nucleic acids. Ideal for AQA Biology students, this resource includes key concepts such as glycosidic bonds, protein functions, and the role of biomolecules in living organisms.
BiologyExplore the essential roles of water and inorganic ions in biological systems. This summary covers the unique properties of water, including polarity, hydrogen bonding, and its function as a solvent, as well as the significance of various inorganic ions in cellular processes. Ideal for CCEA AS Level Biology revision.
BiologyExplore the essential characteristics of water, including its polarity, cohesion, adhesion, and hydrogen bonding. This summary highlights water's role as a solvent, its high boiling point, and its importance for life, making it a crucial topic for A-Level OCR Biology students.
BiologyExplore the essential components of the heart's structure and function in this comprehensive summary for SQA Higher Human Biology, Key Area 2.6. Understand the cardiac cycle, cardiac output, heart conduction system, and the impact of blood pressure on cardiovascular health. Ideal for exam preparation and reinforcing key concepts.
BiologyExplore the critical properties of water, including polarity, cohesion, hydrogen bonding, and its role as a solvent. This summary highlights how these characteristics contribute to water's unique behavior in biological systems, such as its high specific heat capacity and importance in metabolic processes. Ideal for A Level Biology students.
BiologyApp 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
Kat bert
@katbert
Understanding biochemistry is like having a toolkit for analysing life itself - these fundamental tests and molecular structures form the backbone of A-level Biology. From identifying what's in your food to understanding how proteins fold, these concepts will pop up... Show more
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
You'll need to master four key biochemical tests for your exams. Starch turns blue-black with iodine solution, whilst proteins change from blue to purple with biuret reagent. For lipids, mix with ethanol then water - a cloudy emulsion means lipids are present.
Reducing sugars create a colour spectrum with Benedict's reagent, from blue (no sugar) through green, yellow, orange to brick-red (loads of sugar). Non-reducing sugars need boiling with hydrochloric acid first to break them down.
Water's unique properties make life possible. Its high surface tension creates habitats, whilst high specific heat capacity keeps cellular conditions stable. The fact that ice floats protects aquatic life underneath, and water's cohesive properties allow it to be pulled up through plant stems.
Quick Tip: Remember the acronym CHILIS for water properties - Colourless, High surface tension, High latent heat, High specific heat, Ice floats, Liquid at room temp, Strong cohesion!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Protein structure has four levels you must understand. Primary structure is simply the amino acid sequence, whilst secondary structure involves hydrogen bonding creating repeating patterns like alpha-helices. Tertiary structure gives the final 3D shape through various bonds and interactions.
Globular proteins fold into spherical shapes and dissolve in water (like haemoglobin), whereas fibrous proteins remain long and parallel, usually insoluble (like collagen). Quaternary structure involves multiple polypeptide chains working together.
Lipids serve three main functions: insulation, energy storage, and protection. Triglycerides combine glycerol with three fatty acids, whilst phospholipids have just two fatty acids plus a phosphate group, creating molecules with hydrophilic heads and hydrophobic tails.
Exam Focus: Van der Waals forces occur because electrons move constantly, creating temporary positive and negative areas that help molecules stick together - this often appears in extended response questions!
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.
15
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the structure and function of carbohydrates, focusing on monosaccharides and disaccharides. This summary covers key concepts such as glycosidic bonds, condensation and hydrolysis reactions, and the properties of glucose, galactose, and fructose. Ideal for OCR A Level Biology students.
BiologyExplore the essential components of biological molecules in this concise revision guide. Understand the structure, functions, and examples of carbohydrates, proteins, lipids, and nucleic acids. Ideal for AQA Biology students, this resource includes key concepts such as glycosidic bonds, protein functions, and the role of biomolecules in living organisms.
BiologyExplore the essential roles of water and inorganic ions in biological systems. This summary covers the unique properties of water, including polarity, hydrogen bonding, and its function as a solvent, as well as the significance of various inorganic ions in cellular processes. Ideal for CCEA AS Level Biology revision.
BiologyExplore the essential characteristics of water, including its polarity, cohesion, adhesion, and hydrogen bonding. This summary highlights water's role as a solvent, its high boiling point, and its importance for life, making it a crucial topic for A-Level OCR Biology students.
BiologyExplore the essential components of the heart's structure and function in this comprehensive summary for SQA Higher Human Biology, Key Area 2.6. Understand the cardiac cycle, cardiac output, heart conduction system, and the impact of blood pressure on cardiovascular health. Ideal for exam preparation and reinforcing key concepts.
BiologyExplore the critical properties of water, including polarity, cohesion, hydrogen bonding, and its role as a solvent. This summary highlights how these characteristics contribute to water's unique behavior in biological systems, such as its high specific heat capacity and importance in metabolic processes. Ideal for A Level Biology students.
BiologyApp 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