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AQA Biology: Biological Molecules Revision guide
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AQA Biology: Biological Molecules Mind Map Revision
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A Level AQA Biology: Biological Molecules Revision Guide
This guide covers everything you need to know about the four major biological molecules for your AQA A Level Biology exam. These molecules are literally what life is made of, so getting to grips with them now will make the rest of your biology studies much easier.
You'll explore carbohydrates, lipids, proteins, and nucleic acids - their structures, functions, and real-world examples. Each molecule type has its own unique role in keeping living organisms alive and functioning properly.
Quick tip: Think of biological molecules like different tools in a toolkit - each one has specific jobs it's perfectly designed to do!
Carbohydrates: Your Body's Favourite Fuel
Carbohydrates are built from simple sugar units called monosaccharides - think of them as biological Lego blocks that can be joined together in different ways. The simplest ones like glucose give you quick energy, whilst complex ones like starch store energy for later.
You'll find carbohydrates doing two main jobs: providing energy (like glucose powering your brain) or giving structural support (like cellulose making plant cell walls tough). This makes them incredibly versatile molecules.
Common examples include glucose and fructose (simple sugars), sucrose and lactose (double sugars), and starch, cellulose, and glycogen (complex carbohydrates). Remember that plants store energy as starch, whilst animals store it as glycogen.
Remember: If it ends in '-ose', it's probably a sugar!
Lipids: The Body's Energy Storage Champions
Lipids are made from fatty acids joined to glycerol - imagine a three-pronged fork with fatty acid chains hanging off each prong. They're brilliant at storing energy because they pack twice as much energy per gram compared to carbohydrates.
These molecules are your body's ultimate multi-taskers. They store long-term energy as fat, insulate you from the cold, protect your organs from damage, and form the cell membranes that keep your cells intact.
The main types you need to know are triglycerides (storage fats), phospholipids (membrane builders), and cholesterol (membrane stabiliser and hormone precursor). Each has a slightly different structure that perfectly matches its function.
Fun fact: Your brain is about 60% fat - mostly phospholipids and cholesterol!
Proteins: The Ultimate Multitaskers
Proteins are chains of amino acids linked together like beads on a string, then folded into complex 3D shapes. Their shape is absolutely crucial - if a protein loses its shape, it stops working properly.
These molecular machines do almost everything in your body. They speed up reactions as enzymes, carry messages as hormones like insulin, provide structure as collagen in your skin, transport oxygen as haemoglobin, and fight infections as antibodies.
The key thing about proteins is that their specific shape determines their function. Change even one amino acid, and you might completely alter what the protein can do - that's why genetic mutations can have such dramatic effects.
Memory trick: Proteins are like molecular tools - each one has a specific job based on its unique shape!
Nucleic Acids: Life's Instruction Manual
Nucleic acids are built from nucleotides - small units that act like letters in the alphabet of life. These molecules store and transmit all the genetic information that makes you who you are.
There are two main types: DNA stores your genetic blueprint in the cell nucleus, whilst RNA helps translate that information into proteins. DNA is like the master recipe book that stays safely in the kitchen, whilst RNA is like the photocopied recipe you take to the cooking station.
Every nucleotide contains a sugar, a phosphate group, and a base. The sequence of bases spells out the genetic code that determines everything from your eye colour to how your enzymes work.
Think of it this way: If your body were a computer, nucleic acids would be both the hard drive and the software!
Revision Tips for Exam Success
Focus on identifying biological molecules by their building blocks - monosaccharides for carbohydrates, amino acids for proteins, and so on. This pattern recognition will save you time in exams.
Learn the key bond types: glycosidic bonds hold carbohydrates together, whilst peptide bonds link amino acids in proteins. Understanding these connections helps explain how molecules are built and broken down.
Practice making connections between structure and function. For example, why are triglycerides good for energy storage? Because their long fatty acid chains pack lots of energy into a small space.
Work through past paper questions that ask you to identify molecules in different scenarios or explain their functions in specific contexts. The more you practice applying your knowledge, the more confident you'll become.
Exam strategy: Always link structure to function - examiners love seeing that you understand why molecules are shaped the way they are!
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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
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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
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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
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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
AQA Biology: Biological Molecules Mind Map Revision
Azzy
@azzytherevisionhelper
Biological molecules are the essential building blocks of all living things - from the glucose that powers your muscles to the DNA that makes you unique. Understanding these four main types of molecules and how they work will give you... Show more
A Level AQA Biology: Biological Molecules Revision Guide
This guide covers everything you need to know about the four major biological molecules for your AQA A Level Biology exam. These molecules are literally what life is made of, so getting to grips with them now will make the rest of your biology studies much easier.
You'll explore carbohydrates, lipids, proteins, and nucleic acids - their structures, functions, and real-world examples. Each molecule type has its own unique role in keeping living organisms alive and functioning properly.
Quick tip: Think of biological molecules like different tools in a toolkit - each one has specific jobs it's perfectly designed to do!
Sign up to see the contentIt's free!
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Improve your grades
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By signing up you accept Terms of Service and Privacy Policy
Carbohydrates: Your Body's Favourite Fuel
Carbohydrates are built from simple sugar units called monosaccharides - think of them as biological Lego blocks that can be joined together in different ways. The simplest ones like glucose give you quick energy, whilst complex ones like starch store energy for later.
You'll find carbohydrates doing two main jobs: providing energy (like glucose powering your brain) or giving structural support (like cellulose making plant cell walls tough). This makes them incredibly versatile molecules.
Common examples include glucose and fructose (simple sugars), sucrose and lactose (double sugars), and starch, cellulose, and glycogen (complex carbohydrates). Remember that plants store energy as starch, whilst animals store it as glycogen.
Remember: If it ends in '-ose', it's probably a sugar!
Sign up to see the contentIt's free!
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Improve your grades
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By signing up you accept Terms of Service and Privacy Policy
Lipids: The Body's Energy Storage Champions
Lipids are made from fatty acids joined to glycerol - imagine a three-pronged fork with fatty acid chains hanging off each prong. They're brilliant at storing energy because they pack twice as much energy per gram compared to carbohydrates.
These molecules are your body's ultimate multi-taskers. They store long-term energy as fat, insulate you from the cold, protect your organs from damage, and form the cell membranes that keep your cells intact.
The main types you need to know are triglycerides (storage fats), phospholipids (membrane builders), and cholesterol (membrane stabiliser and hormone precursor). Each has a slightly different structure that perfectly matches its function.
Fun fact: Your brain is about 60% fat - mostly phospholipids and cholesterol!
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Proteins: The Ultimate Multitaskers
Proteins are chains of amino acids linked together like beads on a string, then folded into complex 3D shapes. Their shape is absolutely crucial - if a protein loses its shape, it stops working properly.
These molecular machines do almost everything in your body. They speed up reactions as enzymes, carry messages as hormones like insulin, provide structure as collagen in your skin, transport oxygen as haemoglobin, and fight infections as antibodies.
The key thing about proteins is that their specific shape determines their function. Change even one amino acid, and you might completely alter what the protein can do - that's why genetic mutations can have such dramatic effects.
Memory trick: Proteins are like molecular tools - each one has a specific job based on its unique shape!
Sign up to see the contentIt's free!
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By signing up you accept Terms of Service and Privacy Policy
Nucleic Acids: Life's Instruction Manual
Nucleic acids are built from nucleotides - small units that act like letters in the alphabet of life. These molecules store and transmit all the genetic information that makes you who you are.
There are two main types: DNA stores your genetic blueprint in the cell nucleus, whilst RNA helps translate that information into proteins. DNA is like the master recipe book that stays safely in the kitchen, whilst RNA is like the photocopied recipe you take to the cooking station.
Every nucleotide contains a sugar, a phosphate group, and a base. The sequence of bases spells out the genetic code that determines everything from your eye colour to how your enzymes work.
Think of it this way: If your body were a computer, nucleic acids would be both the hard drive and the software!
Sign up to see the contentIt's free!
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By signing up you accept Terms of Service and Privacy Policy
Revision Tips for Exam Success
Focus on identifying biological molecules by their building blocks - monosaccharides for carbohydrates, amino acids for proteins, and so on. This pattern recognition will save you time in exams.
Learn the key bond types: glycosidic bonds hold carbohydrates together, whilst peptide bonds link amino acids in proteins. Understanding these connections helps explain how molecules are built and broken down.
Practice making connections between structure and function. For example, why are triglycerides good for energy storage? Because their long fatty acid chains pack lots of energy into a small space.
Work through past paper questions that ask you to identify molecules in different scenarios or explain their functions in specific contexts. The more you practice applying your knowledge, the more confident you'll become.
Exam strategy: Always link structure to function - examiners love seeing that you understand why molecules are shaped the way they are!
We thought you’d never ask...
What is the Knowunity AI companion?
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.
Where can I download the Knowunity app?
You can download the app from Google Play Store and 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
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.9/5
App Store
4.8/5
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
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