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Responding to change (a2 only)
Infection and response
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Organisms respond to changes in their internal and external environments (a-level only)
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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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3
0
Lucy
30/11/2025
Biology
AQA A Level Biology Carbohydrates Notes
283
•
30 Nov 2025
•
Lucy
@lucy_sldh
Carbohydrates are essential biological molecules that you'll encounter constantly in... Show more
Carbohydrates are made up of just three elements: carbon, hydrogen, and oxygen. Think of them as nature's building blocks and fuel sources rolled into one. The main types you need to know are sugars, starch, and cellulose.
Sugars are the smallest carbohydrates and they're what give sweets their taste. They dissolve easily in water, which makes them perfect for quick energy transport around your body. These sugars fall into two main categories that work like molecular Lego pieces.
Monosaccharides are single sugar units - the individual Lego blocks, if you will. Glucose and fructose are the most important ones to remember. Glucose actually comes in two forms: alpha glucose and beta glucose, which might look nearly identical but have slightly different structures that matter hugely for function.
Quick Tip: Remember that glucose is your body's preferred fuel source - your brain alone uses about 20% of your daily glucose intake!
Disaccharides form when two monosaccharides join together through a condensation reaction - essentially, they stick together whilst kicking out a water molecule. Maltose comes from two glucose molecules joining up, whilst sucrose (table sugar) forms when glucose meets fructose.
Polysaccharides are the giants of the carbohydrate world - long chains made from hundreds or thousands of monosaccharide units. They're like massive molecular chains where each link is a simple sugar.
Starch is plants' way of storing glucose for later use. It's made up of two different types: amylose and amylopectin, both built from glucose units. Because starch molecules are insoluble and compact, they're brilliant for long-term energy storage without affecting the plant's water balance.
Cellulose is also made from glucose, but the way the glucose units bond together creates long, straight molecules instead of branched ones. This difference in structure makes cellulose incredibly strong rather than useful for energy storage.
Key Point: The same building blocks (glucose) can create completely different materials just by changing how they're connected - it's all about the bonding!
Cellulose molecules bundle together to form microfibrils, which are like biological cables that strengthen plant cell walls. Multiple cellulose chains lie side by side, held together by numerous weak hydrogen bonds that collectively create remarkable strength.
This is why cellulose makes such excellent structural material - those hydrogen bonds between molecules create a network that's tough enough to support massive trees yet flexible enough to allow growth. It's nature's version of reinforced concrete, but made entirely from glucose!
Remember: Microfibrils are cellulose's secret weapon for giving plants their structural strength - without them, plants would be as floppy as cooked spaghetti!
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.
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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
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
Lucy
@lucy_sldh
Carbohydrates are essential biological molecules that you'll encounter constantly in biology - from the glucose powering your brain right now to the cellulose in every plant around you. Understanding their structure and function is crucial for grasping how living organisms... Show more
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Carbohydrates are made up of just three elements: carbon, hydrogen, and oxygen. Think of them as nature's building blocks and fuel sources rolled into one. The main types you need to know are sugars, starch, and cellulose.
Sugars are the smallest carbohydrates and they're what give sweets their taste. They dissolve easily in water, which makes them perfect for quick energy transport around your body. These sugars fall into two main categories that work like molecular Lego pieces.
Monosaccharides are single sugar units - the individual Lego blocks, if you will. Glucose and fructose are the most important ones to remember. Glucose actually comes in two forms: alpha glucose and beta glucose, which might look nearly identical but have slightly different structures that matter hugely for function.
Quick Tip: Remember that glucose is your body's preferred fuel source - your brain alone uses about 20% of your daily glucose intake!
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Disaccharides form when two monosaccharides join together through a condensation reaction - essentially, they stick together whilst kicking out a water molecule. Maltose comes from two glucose molecules joining up, whilst sucrose (table sugar) forms when glucose meets fructose.
Polysaccharides are the giants of the carbohydrate world - long chains made from hundreds or thousands of monosaccharide units. They're like massive molecular chains where each link is a simple sugar.
Starch is plants' way of storing glucose for later use. It's made up of two different types: amylose and amylopectin, both built from glucose units. Because starch molecules are insoluble and compact, they're brilliant for long-term energy storage without affecting the plant's water balance.
Cellulose is also made from glucose, but the way the glucose units bond together creates long, straight molecules instead of branched ones. This difference in structure makes cellulose incredibly strong rather than useful for energy storage.
Key Point: The same building blocks (glucose) can create completely different materials just by changing how they're connected - it's all about the bonding!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Cellulose molecules bundle together to form microfibrils, which are like biological cables that strengthen plant cell walls. Multiple cellulose chains lie side by side, held together by numerous weak hydrogen bonds that collectively create remarkable strength.
This is why cellulose makes such excellent structural material - those hydrogen bonds between molecules create a network that's tough enough to support massive trees yet flexible enough to allow growth. It's nature's version of reinforced concrete, but made entirely from glucose!
Remember: Microfibrils are cellulose's secret weapon for giving plants their structural strength - without them, plants would be as floppy as cooked spaghetti!
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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Explore the structure and function of carbohydrates, including monosaccharides, disaccharides, and polysaccharides. This summary covers key concepts such as glycosidic bonds, condensation and hydrolysis reactions, and the roles of starch, glycogen, and cellulose in biological systems. Ideal for A Level Biology students studying biological molecules.
BiologyExplore essential carbohydrate testing methods including the iodine test for starch and Benedict's test for reducing sugars. This summary covers the structure of carbohydrates, the significance of polysaccharides like starch and glycogen, and the biochemical reactions involved in carbohydrate digestion. Ideal for AQA A-Level Biology students.
BiologyExplore the key types of polysaccharides, including cellulose, glycogen, and starch. This summary highlights their structures, bonding types, and biological significance, tailored for A-level Biology students. Understand the role of glycosidic bonds and the implications for digestion and energy storage.
BiologyExplore the fundamentals of biological molecules, including monomers, polymers, and carbohydrates. This summary covers key concepts such as monosaccharides, disaccharides, and the structure of glucose. Ideal for A-level Biology students seeking to understand the building blocks of life.
BiologyExplore the essential characteristics of monosaccharides, including their structure, types (pentose and hexose), and properties such as solubility in water. This summary highlights key concepts like glucose, fructose, and galactose, and explains the significance of hydrogen bonding in their hydrophilic nature. Ideal for students studying biological molecules.
BiologyExplore the mechanisms of carbohydrate formation, including condensation and hydrolysis reactions. This summary covers the structure of polysaccharides like amylose and amylopectin, the types of glycosidic bonds, and the formation of disaccharides such as lactose, maltose, and sucrose. Ideal for A-level biology students studying biomolecules and macromolecules.
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