Biological molecules are the building blocks of life. From carbohydrates... Show more
Combined Science
English Literature
SociologySign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
123
•
Updated Mar 15, 2026
•
Complete Notes on Topic 1 for A Level Biology
J
john
@johnnn23
1 / 10
Monomers and Polymers
Ever wondered how complex biological structures are built? They start with monomers - small repeating units that join together to form larger molecules. When two monomers combine through a condensation reaction, they form a chemical bond and release a water molecule.
These chains of monomers create polymers, large molecules made up of many identical smaller units. The reverse process is hydrolysis, where molecules are separated by breaking a chemical bond using a water molecule.
Key examples include nucleotides forming polynucleotides, monosaccharides (like glucose) forming polysaccharides (like starch), and amino acids joining to create polypeptides (proteins).
💡 Think of monomers as biological building blocks - just as individual LEGO pieces connect to build complex structures, monomers join through condensation reactions to create the macromolecules essential for life!
Carbohydrates
Carbohydrates are your body's primary energy source and have the formula C₍ₙ₎H₍₂ₙ₎O₍ₙ₎. Monosaccharides like glucose are single sugar units, while disaccharides form when two monosaccharides join through a glycosidic bond in a condensation reaction (examples include maltose, sucrose and lactose).
When many monosaccharides link together, they form polysaccharides like starch, glycogen, and cellulose. Each serves a distinct purpose: starch stores energy in plants, glycogen stores energy in animals, and cellulose provides structural support in plant cell walls.
You can identify carbohydrates through simple tests. For reducing sugars, Benedict's test produces a red precipitate when positive. For non-reducing sugars, acid hydrolysis is needed before Benedict's test. Starch turns blue-black when iodine solution is added.
🧪 Laboratory tip: When measuring sugar concentration, you can create a calibration curve using known concentrations with Benedict's reagent and a colorimeter, then compare your unknown sample's absorbance to determine its concentration!
Lipids
Lipids are hydrophobic molecules that include triglycerides and phospholipids. Triglycerides form when glycerol combines with three fatty acids through condensation reactions, creating three ester bonds and removing three water molecules.
The structure of fatty acids includes a carboxyl group (COOH) and a variable hydrocarbon chain that can be saturated or unsaturated . This structure makes lipids excellent energy storage molecules - they pack more C-H bonds per carbon atom than carbohydrates, releasing more energy during respiration.
Phospholipids are modified triglycerides where one fatty acid is replaced by a phosphate group. Their structure - with hydrophilic phosphate heads and hydrophobic fatty acid tails - allows them to form the bilayers that make up cell membranes, controlling what enters and exits cells.
💦 The hydrophobic nature of lipids makes them easy to detect - when you add ethanol and water to a food sample containing lipids and shake it, a distinctive milky white emulsion forms!
Proteins
Proteins start with amino acids, which have a distinctive structure featuring an amine group, a carboxyl group, and a variable R side chain. Twenty common amino acids exist, differing only in their R group.
Amino acids join through condensation reactions, forming peptide bonds between the carboxyl group of one amino acid and the amine group of another. Two linked amino acids form a dipeptide, while many linked together create a polypeptide.
Proteins have four levels of structure that determine their function. The primary structure is simply the sequence of amino acids. The secondary structure involves 2D folding into alpha helices or beta pleated sheets due to hydrogen bonding. The tertiary structure creates a 3D shape through various bonds between R groups. When multiple polypeptide chains join, they form a quaternary structure.
🧪 Testing for proteins is straightforward - add Biuret's reagent to your sample and watch for a purple (lilac) colour change, which indicates the presence of peptide bonds!
Enzymes
Enzymes are biological catalysts that speed up reactions by lowering the activation energy required. Each enzyme has a specific active site where substrates bind, with a shape complementary to its specific substrate.
The induced fit model explains how enzymes work: when a substrate binds to the active site, the enzyme changes shape slightly to fit the substrate perfectly, forming an enzyme-substrate complex. This distorts bonds in the substrate, lowering activation energy and accelerating the reaction.
Several factors affect enzyme activity. As temperature increases to an optimum, reaction rates increase due to more kinetic energy and enzyme-substrate collisions. However, excessive heat causes enzymes to denature as hydrogen and ionic bonds break. Similarly, changes in pH can denature enzymes by altering their tertiary structure.
🔍 Enzyme inhibitors can control reaction rates! Competitive inhibitors resemble the substrate and block the active site, while non-competitive inhibitors bind elsewhere on the enzyme, changing the active site shape. Increasing substrate concentration can overcome competitive inhibition but has no effect on non-competitive inhibition!
DNA Structure and Function
DNA holds the genetic information that codes for proteins. It's formed from nucleotides that join through condensation reactions, creating phosphodiester bonds between the phosphate group of one nucleotide and the deoxyribose sugar of another.
Each nucleotide consists of three components: a phosphate group, a deoxyribose sugar, and a nitrogenous base (adenine, thymine, guanine, or cytosine). DNA forms its distinctive double helix structure through hydrogen bonds between complementary base pairs - adenine with thymine and guanine with cytosine.
DNA's structure perfectly suits its function. Its double-stranded nature provides stability and protection for genetic information. The complementary base pairing enables accurate replication, while the length of DNA molecules allows them to store vast amounts of information.
🧬 DNA's structure was a revolutionary discovery! Watson and Crick's model showed how the molecule's design enables both information storage and the ability to create exact copies of itself through complementary base pairing.
DNA Replication
DNA replication is semi-conservative - each new DNA molecule contains one original strand and one newly synthesized strand. This elegant process ensures genetic information is preserved across cell divisions.
The replication process begins when DNA helicase breaks the hydrogen bonds between base pairs, unwinding the double helix. Both strands then act as templates, with free DNA nucleotides attaching to complementary bases. DNA polymerase moves along each strand, joining adjacent nucleotides by forming phosphodiester bonds.
DNA polymerase moves in opposite directions along the two strands because DNA has antiparallel strands with different arrangements of nucleotides at each end. The enzyme's active site has a specific shape that can only bind to substrates with a complementary arrangement.
🔬 The semi-conservative nature of DNA replication was proven through a brilliant experiment using nitrogen isotopes! When bacteria grown with heavy nitrogen (¹⁵N) were transferred to a medium with light nitrogen (¹⁴N), the resulting DNA molecules contained one heavy strand and one light strand - exactly as the semi-conservative model predicted.
ATP
ATP (adenosine triphosphate) is the energy currency of cells. Its structure includes an adenine base, a ribose sugar, and three phosphate groups - and it's the phosphate bonds that store energy.
When cells need energy, ATP breaks down through hydrolysis, catalyzed by the enzyme ATP hydrolase. This reaction converts ATP to ADP (adenosine diphosphate) and releases an inorganic phosphate (Pi), along with energy. The beauty of ATP is that it releases energy in small, manageable amounts that cells can use immediately.
ATP is constantly being recycled in your cells. It's resynthesized through condensation reactions catalyzed by ATP synthase during respiration and photosynthesis. This cycling of ATP to ADP and back again creates an efficient energy transfer system within cells.
⚡ ATP is a brilliant cellular solution for energy management! Unlike burning glucose directly (which would release too much energy at once), ATP hydrolysis provides energy in small, controlled amounts - like spending from a current account rather than cashing in your entire savings at once.
Water
Water is crucial for life, with properties that make it the perfect biological solvent. Its polar nature creates hydrogen bonds between water molecules, giving water unique characteristics that support life processes.
Water's high specific heat capacity means it can absorb or release substantial heat with minimal temperature change. This helps organisms maintain stable internal temperatures and creates stable aquatic habitats. Its large latent heat of vaporization enables efficient cooling through evaporation, as with sweating.
The strong cohesion between water molecules supports water columns in plant transport systems and creates surface tension that allows some organisms to walk on water. As a solvent, water enables metabolic reactions and the transport of substances throughout organisms.
💧 Water's amazing properties come from its bent molecular shape! The oxygen atom pulls electrons away from the hydrogen atoms, creating a molecule with a slightly negative end and a slightly positive end - making water the universal solvent for life's chemistry.
Inorganic Ions
Inorganic ions may be small, but they're mighty in their biological functions. Found dissolved in cellular fluids, these charged particles are essential for numerous life processes.
Hydrogen ions (H⁺) regulate pH in the body, which is crucial for enzyme function. Too many H⁺ ions create acidic conditions that can denature enzymes. Sodium ions (Na⁺) are vital for nerve function, helping to generate action potentials and assisting with the co-transport of nutrients like glucose into cells.
Iron ions (Fe²⁺) form part of the haemoglobin molecule, allowing oxygen to bind for transport throughout the body. Phosphate ions (PO₄³⁻) contribute to DNA and RNA structure, form part of ATP for energy release, and constitute the hydrophilic portion of phospholipids in cell membranes.
⚛️ Despite making up only a tiny fraction of your body weight, inorganic ions are absolutely essential for life! Without the right balance of these charged particles, nerve signals wouldn't fire, oxygen wouldn't be transported, and your cell membranes couldn't function properly.
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.
Most popular content: Enzyme
Most popular content in Biology
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5
App Store
4.7/5
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 Knowunity AI. 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 Knowunity AI. 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
Complete Notes on Topic 1 for A Level Biology
J
john
@johnnn23
Biological molecules are the building blocks of life. From carbohydrates to proteins, these molecules play essential roles in structure, energy storage, and cellular functions. Understanding how they're formed and how they work is fundamental to biology and biochemistry.
Monomers and Polymers
Ever wondered how complex biological structures are built? They start with monomers - small repeating units that join together to form larger molecules. When two monomers combine through a condensation reaction, they form a chemical bond and release a water molecule.
These chains of monomers create polymers, large molecules made up of many identical smaller units. The reverse process is hydrolysis, where molecules are separated by breaking a chemical bond using a water molecule.
Key examples include nucleotides forming polynucleotides, monosaccharides (like glucose) forming polysaccharides (like starch), and amino acids joining to create polypeptides (proteins).
💡 Think of monomers as biological building blocks - just as individual LEGO pieces connect to build complex structures, monomers join through condensation reactions to create the macromolecules essential for life!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Carbohydrates
Carbohydrates are your body's primary energy source and have the formula C₍ₙ₎H₍₂ₙ₎O₍ₙ₎. Monosaccharides like glucose are single sugar units, while disaccharides form when two monosaccharides join through a glycosidic bond in a condensation reaction (examples include maltose, sucrose and lactose).
When many monosaccharides link together, they form polysaccharides like starch, glycogen, and cellulose. Each serves a distinct purpose: starch stores energy in plants, glycogen stores energy in animals, and cellulose provides structural support in plant cell walls.
You can identify carbohydrates through simple tests. For reducing sugars, Benedict's test produces a red precipitate when positive. For non-reducing sugars, acid hydrolysis is needed before Benedict's test. Starch turns blue-black when iodine solution is added.
🧪 Laboratory tip: When measuring sugar concentration, you can create a calibration curve using known concentrations with Benedict's reagent and a colorimeter, then compare your unknown sample's absorbance to determine its concentration!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Lipids
Lipids are hydrophobic molecules that include triglycerides and phospholipids. Triglycerides form when glycerol combines with three fatty acids through condensation reactions, creating three ester bonds and removing three water molecules.
The structure of fatty acids includes a carboxyl group (COOH) and a variable hydrocarbon chain that can be saturated or unsaturated . This structure makes lipids excellent energy storage molecules - they pack more C-H bonds per carbon atom than carbohydrates, releasing more energy during respiration.
Phospholipids are modified triglycerides where one fatty acid is replaced by a phosphate group. Their structure - with hydrophilic phosphate heads and hydrophobic fatty acid tails - allows them to form the bilayers that make up cell membranes, controlling what enters and exits cells.
💦 The hydrophobic nature of lipids makes them easy to detect - when you add ethanol and water to a food sample containing lipids and shake it, a distinctive milky white emulsion forms!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Proteins
Proteins start with amino acids, which have a distinctive structure featuring an amine group, a carboxyl group, and a variable R side chain. Twenty common amino acids exist, differing only in their R group.
Amino acids join through condensation reactions, forming peptide bonds between the carboxyl group of one amino acid and the amine group of another. Two linked amino acids form a dipeptide, while many linked together create a polypeptide.
Proteins have four levels of structure that determine their function. The primary structure is simply the sequence of amino acids. The secondary structure involves 2D folding into alpha helices or beta pleated sheets due to hydrogen bonding. The tertiary structure creates a 3D shape through various bonds between R groups. When multiple polypeptide chains join, they form a quaternary structure.
🧪 Testing for proteins is straightforward - add Biuret's reagent to your sample and watch for a purple (lilac) colour change, which indicates the presence of peptide bonds!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Enzymes
Enzymes are biological catalysts that speed up reactions by lowering the activation energy required. Each enzyme has a specific active site where substrates bind, with a shape complementary to its specific substrate.
The induced fit model explains how enzymes work: when a substrate binds to the active site, the enzyme changes shape slightly to fit the substrate perfectly, forming an enzyme-substrate complex. This distorts bonds in the substrate, lowering activation energy and accelerating the reaction.
Several factors affect enzyme activity. As temperature increases to an optimum, reaction rates increase due to more kinetic energy and enzyme-substrate collisions. However, excessive heat causes enzymes to denature as hydrogen and ionic bonds break. Similarly, changes in pH can denature enzymes by altering their tertiary structure.
🔍 Enzyme inhibitors can control reaction rates! Competitive inhibitors resemble the substrate and block the active site, while non-competitive inhibitors bind elsewhere on the enzyme, changing the active site shape. Increasing substrate concentration can overcome competitive inhibition but has no effect on non-competitive inhibition!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
DNA Structure and Function
DNA holds the genetic information that codes for proteins. It's formed from nucleotides that join through condensation reactions, creating phosphodiester bonds between the phosphate group of one nucleotide and the deoxyribose sugar of another.
Each nucleotide consists of three components: a phosphate group, a deoxyribose sugar, and a nitrogenous base (adenine, thymine, guanine, or cytosine). DNA forms its distinctive double helix structure through hydrogen bonds between complementary base pairs - adenine with thymine and guanine with cytosine.
DNA's structure perfectly suits its function. Its double-stranded nature provides stability and protection for genetic information. The complementary base pairing enables accurate replication, while the length of DNA molecules allows them to store vast amounts of information.
🧬 DNA's structure was a revolutionary discovery! Watson and Crick's model showed how the molecule's design enables both information storage and the ability to create exact copies of itself through complementary base pairing.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
DNA Replication
DNA replication is semi-conservative - each new DNA molecule contains one original strand and one newly synthesized strand. This elegant process ensures genetic information is preserved across cell divisions.
The replication process begins when DNA helicase breaks the hydrogen bonds between base pairs, unwinding the double helix. Both strands then act as templates, with free DNA nucleotides attaching to complementary bases. DNA polymerase moves along each strand, joining adjacent nucleotides by forming phosphodiester bonds.
DNA polymerase moves in opposite directions along the two strands because DNA has antiparallel strands with different arrangements of nucleotides at each end. The enzyme's active site has a specific shape that can only bind to substrates with a complementary arrangement.
🔬 The semi-conservative nature of DNA replication was proven through a brilliant experiment using nitrogen isotopes! When bacteria grown with heavy nitrogen (¹⁵N) were transferred to a medium with light nitrogen (¹⁴N), the resulting DNA molecules contained one heavy strand and one light strand - exactly as the semi-conservative model predicted.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
ATP
ATP (adenosine triphosphate) is the energy currency of cells. Its structure includes an adenine base, a ribose sugar, and three phosphate groups - and it's the phosphate bonds that store energy.
When cells need energy, ATP breaks down through hydrolysis, catalyzed by the enzyme ATP hydrolase. This reaction converts ATP to ADP (adenosine diphosphate) and releases an inorganic phosphate (Pi), along with energy. The beauty of ATP is that it releases energy in small, manageable amounts that cells can use immediately.
ATP is constantly being recycled in your cells. It's resynthesized through condensation reactions catalyzed by ATP synthase during respiration and photosynthesis. This cycling of ATP to ADP and back again creates an efficient energy transfer system within cells.
⚡ ATP is a brilliant cellular solution for energy management! Unlike burning glucose directly (which would release too much energy at once), ATP hydrolysis provides energy in small, controlled amounts - like spending from a current account rather than cashing in your entire savings at once.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Water
Water is crucial for life, with properties that make it the perfect biological solvent. Its polar nature creates hydrogen bonds between water molecules, giving water unique characteristics that support life processes.
Water's high specific heat capacity means it can absorb or release substantial heat with minimal temperature change. This helps organisms maintain stable internal temperatures and creates stable aquatic habitats. Its large latent heat of vaporization enables efficient cooling through evaporation, as with sweating.
The strong cohesion between water molecules supports water columns in plant transport systems and creates surface tension that allows some organisms to walk on water. As a solvent, water enables metabolic reactions and the transport of substances throughout organisms.
💧 Water's amazing properties come from its bent molecular shape! The oxygen atom pulls electrons away from the hydrogen atoms, creating a molecule with a slightly negative end and a slightly positive end - making water the universal solvent for life's chemistry.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Inorganic Ions
Inorganic ions may be small, but they're mighty in their biological functions. Found dissolved in cellular fluids, these charged particles are essential for numerous life processes.
Hydrogen ions (H⁺) regulate pH in the body, which is crucial for enzyme function. Too many H⁺ ions create acidic conditions that can denature enzymes. Sodium ions (Na⁺) are vital for nerve function, helping to generate action potentials and assisting with the co-transport of nutrients like glucose into cells.
Iron ions (Fe²⁺) form part of the haemoglobin molecule, allowing oxygen to bind for transport throughout the body. Phosphate ions (PO₄³⁻) contribute to DNA and RNA structure, form part of ATP for energy release, and constitute the hydrophilic portion of phospholipids in cell membranes.
⚛️ Despite making up only a tiny fraction of your body weight, inorganic ions are absolutely essential for life! Without the right balance of these charged particles, nerve signals wouldn't fire, oxygen wouldn't be transported, and your cell membranes couldn't function properly.
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.
2
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Mock Exam
Quiz
Flashcards
Essay
Similar content
Biological Molecules Overview
Explore the fundamentals of monomers and polymers in biological molecules. This summary covers key concepts such as the structure of glucose, types of carbohydrates, and the processes of condensation and hydrolysis. Ideal for Year 12 Biology students preparing for exams.
Biology12
Carbohydrate Structures Explained
Explore the fundamentals of carbohydrates, including monosaccharides, disaccharides, and polysaccharides. This summary covers key concepts such as monomers, condensation, and hydrolysis, with clear definitions and examples like glucose, maltose, and starch. Ideal for AS level students seeking to understand carbohydrate chemistry.
Biology12
Understanding Biological Molecules
Explore the essential concepts of biological molecules, including the roles of water, monomers, and polymers. This summary covers carbohydrates, their types (monosaccharides, disaccharides, polysaccharides), and key processes like condensation and hydrolysis. Ideal for biology students seeking to grasp the fundamentals of biomolecules and their significance in metabolic reactions.
Biology12
Biomolecules Overview
Explore the essential components of life with this comprehensive summary on biomolecules, including carbohydrates, proteins, lipids, and their functions. Understand key concepts such as peptide bonds, dehydration synthesis, and the properties of water that influence biological processes. Ideal for students studying biochemistry and molecular biology.
Biology12
Biological Molecules Overview
Comprehensive A-Level Biology notes covering essential biological molecules including carbohydrates (starch, glycogen, cellulose), proteins (amino acids, structure), lipids, and enzymes. Understand monomers, polymers, and the role of enzymes in biochemical reactions. Ideal for exam preparation and revision.
Biology12
Understanding Metabolism
Explore the fundamentals of metabolism, including its definition, examples like respiration, and the metabolic rate. This summary covers the three main types of food molecules: carbohydrates, proteins, and lipids, essential for GCSE Biology students. Enhance your understanding of cellular processes and energy usage in living organisms.
Biology9
Most popular content: Enzyme
Most popular content in Biology
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5
App Store
4.7/5
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 Knowunity AI. 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 Knowunity AI. 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