Ever wonder what makes your DNA different from a piece...
Comprehensive Guide to Biological Molecules for OCR A-Level Biology











Building Blocks of Life: Monomers and Polymers
Think of biological molecules like construction sets - monomers are the individual bricks, whilst polymers are the finished structures built from identical pieces joined together. This simple concept explains how your body creates everything from energy stores to muscle fibres.
Two key reactions control this molecular construction site. Condensation reactions join monomers together by removing water molecules, like welding pieces with the loss of steam. Hydrolysis reactions do the opposite - they break apart large molecules by adding water back, which is exactly what happens when you digest food.
Carbohydrates follow the CHO formula and serve as your body's primary energy source. Monosaccharides like glucose are single sugar units that dissolve easily in blood for quick transport around your body.
Quick Tip: Remember that alpha glucose (used in starch) has hydrogen above the first carbon, whilst beta glucose (used in cellulose) has the OH group above - this tiny difference completely changes their properties!

Sugar Chemistry: From Simple to Complex
Ribose and deoxyribose might sound complicated, but they're just five-carbon sugars with a crucial difference. Ribose (in RNA) keeps all its OH groups, whilst deoxyribose (in DNA) loses one oxygen atom - making DNA more stable for long-term information storage.
When two monosaccharides join through condensation reactions, they form glycosidic bonds and create disaccharides like table sugar. These double sugars remain soluble and sweet, perfect for quick energy hits.
Polysaccharides are the heavy-duty storage units - long chains of sugars linked by glycosidic bonds. Most are insoluble due to their massive, branched structures, which makes them ideal for storing energy without affecting your cells' water balance.
Exam Focus: Each glycosidic bond formation releases one water molecule - count the bonds to work out how much water is produced in synthesis reactions!

Energy Storage: Starch and Its Components
Plants face the same problem you do - they need to store excess energy for later use. Starch solves this perfectly by being completely insoluble, so it won't mess with the plant's water balance while storing massive amounts of glucose.
Amylose forms unbranched chains that coil into tight spirals, packing efficiently like a compressed spring. Its compact structure makes it brilliant for storage but slow to break down. Amylopectin takes a different approach with its branched design, allowing enzymes to attack multiple points simultaneously for faster glucose release.
The branching happens through different bond types - straight sections use 1-4 glycosidic bonds, whilst branch points use 1-6 bonds. This creates a tree-like structure that balances storage efficiency with accessibility.
Memory Trick: Amylose = "A-my-coiled" (coiled structure), Amylopectin = "A-my-branches" (branched structure)!

Animal Storage and Structure: Glycogen and Cellulose
Glycogen is basically amylopectin on steroids - it has branches every 8-12 glucose units compared to starch's longer straight sections. This ultra-branched structure reflects animals' higher metabolic demands and need for rapid energy release during movement.
Cellulose breaks all the rules by using beta glucose, creating straight, unbranched chains where every other glucose molecule flips 180°. This alternating pattern allows adjacent molecules to form hydrogen bonds, creating rope-like microfibrils of incredible strength.
Triglycerides represent a completely different storage strategy. Made from glycerol plus three fatty acids joined by ester bonds, they pack almost twice the energy of carbohydrates. Their hydrophobic nature means they won't absorb water and swell up like a sponge.
Real-world Connection: Cellulose's strength-to-weight ratio rivals steel - that's why it's perfect for plant cell walls and why we use it to make paper!

Fats and Membrane Structure
Saturated fatty acids pack together tightly like straight pencils in a box, whilst unsaturated fatty acids have kinks from double bonds that push molecules apart. More kinks mean lower melting points - think of butter (saturated) versus olive oil (unsaturated) at room temperature.
Phospholipids are the molecular architects of cell membranes. With hydrophilic phosphate heads and hydrophobic fatty acid tails, they automatically arrange into bilayers - the heads face outward toward water whilst the tails hide inside.
This bilayer structure creates a selectively permeable barrier. Small, non-polar molecules can slip through the fatty acid centre, but water-soluble substances get blocked. It's like having a security system that only lets certain molecules pass.
Visual Learning: Picture phospholipids as matchsticks with magnetic heads - they'll always orient themselves with heads touching water and tails clustering together!

Membrane Fluidity and Protein Basics
Cholesterol acts like a membrane thermostat, keeping cell membranes at just the right consistency. In hot conditions, it prevents excessive fluidity; in cold conditions, it stops the membrane from becoming too rigid and cracking.
Proteins are the workhorses of your cells, built from chains of amino acids linked by peptide bonds. Each amino acid has the same basic structure except for its R group - this variable side chain gives each amino acid its unique personality.
The condensation reaction between amino acids is straightforward: the hydrogen from one amino acid's amine group combines with the hydroxyl group from another's carboxyl group, releasing water and forming a covalent peptide bond.
Study Strategy: Focus on the R groups when learning amino acids - they determine everything about how the protein will fold and function!

Protein Bonds and Structure Levels
Four types of bonds hold proteins in their final shapes. Hydrogen bonds form between slightly charged atoms but break easily with heat. Ionic bonds create strong attractions between oppositely charged R groups. Disulfide bridges form the strongest covalent bonds between sulfur-containing amino acids.
Primary structure is simply the sequence of amino acids - change even one, and you change the entire protein. Secondary structure introduces basic folding patterns like alpha helixes (tight spirals) and beta pleated sheets (parallel chains with hydrogen bonds between them).
Tertiary structure creates the final 3D shape through complex interactions between R groups. Hydrophobic R groups cluster inward whilst hydrophilic ones face outward, stabilised by all four bond types working together.
Exam Essential: Temperature and pH changes break hydrogen bonds first, which is why proteins denature (lose their shape) when you cook them!

Protein Folding and Quaternary Structure
Quaternary structure only exists in proteins with multiple polypeptide chains, called subunits. Each subunit has its own tertiary structure, but they work together like different instruments in an orchestra to create the protein's final function.
The four structural levels build upon each other logically. Primary determines secondary, secondary influences tertiary, and tertiary affects how multiple chains interact in quaternary structures. It's like following a recipe where each step depends on getting the previous one right.
Understanding these levels helps explain why protein folding is so critical. A single amino acid change in the primary structure can cascade through all levels, potentially destroying the protein's function - this is what happens in genetic diseases like sickle cell anemia.
Connection Point: Computer modelling now predicts protein shapes from amino acid sequences, revolutionising drug design by showing how medicines might interact with target proteins!

Globular Proteins: Specialists in Action
Globular proteins are the specialists of the protein world - compact, spherical, and designed for specific jobs. Their hydrophilic R groups face outward for solubility, whilst hydrophobic groups cluster inside, making them perfect for transport in body fluids.
Haemoglobin exemplifies sophisticated protein design with four polypeptide chains, each carrying an iron-containing haem group. This quaternary structure allows cooperative oxygen binding - when one chain grabs oxygen, it makes the others more likely to bind too.
Insulin and pepsin show globular proteins' versatility. Insulin's compact, soluble structure lets it travel through blood to regulate glucose levels, whilst pepsin's stable tertiary structure survives stomach acid to digest other proteins.
Key Insight: Prosthetic groups like haem aren't made of amino acids but are essential for protein function - removing iron from haemoglobin makes it useless for oxygen transport!

Fibrous Proteins: The Body's Construction Materials
Fibrous proteins are your body's building materials - long, strong, and perfectly designed for structural roles. Their repetitive sequences and cross-linked chains create incredible tensile strength, like biological steel cables.
Collagen forms the framework for skin, tendons, and bones. Its flexibility allows movement whilst providing strength, and its ability to bind minerals makes it essential for bone formation. Keratin varies from flexible (skin) to rigid (nails) depending on how many disulfide bridges cross-link its structure.
Elastin solves the problem of tissues that need to stretch and spring back. Found in skin, blood vessels, and lung tissue, it allows these structures to expand under pressure then return to their original size.
Real-world Application: Understanding collagen structure helps explain why vitamin C deficiency causes scurvy - without it, collagen can't form properly, leading to weak connective tissues!
We thought you’d never ask...
Similar content
Most popular content: Proteins
4A-Level Biology Active Recall
Enhance your understanding of A-Level OCR Biology with this comprehensive active recall resource. Covering key concepts such as cell structure, enzyme function, and ecological interactions, this study material is designed to reinforce your knowledge and improve exam performance. Ideal for revision and self-assessment.
Understanding Protein Structures
Explore the four levels of protein structure: primary, secondary, tertiary, and quaternary. This detailed summary covers key concepts such as peptide bonds, hydrogen bonds, and the differences between globular and fibrous proteins. Ideal for A Level Biology students preparing for exams.
TOPIC 1: A-Level Biology
Topic 1 (Biological Molecules, More Biological Molecules) for A-Level Biology
Proteins
Paper 1. What is a protein? What it’s structure? What are types of bonding involved? How to test for proteins? Globular VS Fibrous. Haemoglobin VS Collagen.
Most popular content in Biology
9Cell Biology and Cell structure
cell structures
The functions of subcellular structures - B1 Biology
Flashcards on the different functions of subcellular structures: cell membrane, nucleus, mitochondria, ribosomes, cytoplasm, permant vacuole, chloroplasts and cell wall.
1.cells Gcse biology question cards
combined science higher biology
AQA Biology: Key Concepts
Explore essential AQA Biology topics including Photosynthesis, Respiration, Homeostasis, Genetics, and Ecology. This comprehensive knowledge organizer covers key concepts such as energy transfer, hormonal control, and genetic variation, providing a solid foundation for your studies. Ideal for exam preparation and understanding biological processes.
Biology Paper 1 quiz
this is a simple quiz on key knowledge needed for paper 1
Types of cells
biology
A-Level Biology Year 1 Overview
Comprehensive summary of AQA A-Level Biology Year 1, covering key topics such as cellular structure, protein synthesis, immune response, gas exchange, and more. Ideal for exam preparation and understanding biological concepts. Includes detailed insights into cellular processes, biological classification, and the circulatory system.
biology paper 1
all notes
biology paper 1
these are some exam questions for biology paper which are more likely to come up in exams
Most popular content
9Sociology of Education Overview
Explore comprehensive A-Level Sociology notes on the education system, covering key theories, policies, and sociological perspectives. This resource includes insights on marketisation, gender roles, cultural deprivation, and educational inequalities, providing a thorough understanding of how education shapes social stratification and individual achievement. Ideal for exam preparation and in-depth study.
Sociology of Families: Comprehensive Revision
Dive into an extensive overview of family dynamics, perspectives, and patterns in sociology. This resource covers key concepts such as family diversity, gender roles, marriage, and the impact of social policies on family structures. Perfect for A-Level Sociology students preparing for Paper 2.
Criminology: Crime & Punishment Overview
Comprehensive mindmaps covering key concepts in the Crime and Punishment topic for WJEC Criminology Unit 4. This resource includes detailed insights into the Criminal Justice System, crime prevention strategies, sentencing models, and the roles of various agencies. Ideal for A-Level revision, ensuring you grasp essential theories and legislative processes to excel in your exams.
Comprehensive Crime & Deviance Overview
Explore an extensive revision of crime and deviance topics, including theories, types of crime, and the impact of media. This resource covers key concepts such as Marxism, functionalism, gender and crime, and the influence of globalization on criminal behavior. Ideal for students seeking a thorough understanding of criminology and its various theories. Type: Full Topic Revision.
Cell Biology and Cell structure
cell structures
WJEC Unit 4 Criminology
Criminology unit 4 detailed revision note
Sociological Theories Overview
Comprehensive revision of key sociological theories including Functionalism, Marxism, Feminism, and Interpretivism. Explore concepts like value freedom, identity formation, and the critique of social control. Ideal for AQA A-Level Sociology students preparing for exams. This summary covers essential theories and their implications in sociology, providing a clear understanding of each perspective.
The functions of subcellular structures - B1 Biology
Flashcards on the different functions of subcellular structures: cell membrane, nucleus, mitochondria, ribosomes, cytoplasm, permant vacuole, chloroplasts and cell wall.
1.cells Gcse biology question cards
combined science higher biology
Students love us — and so will you.
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.
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.
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.
Comprehensive Guide to Biological Molecules for OCR A-Level Biology
Ever wonder what makes your DNA different from a piece of toast? It all comes down to biological molecules - the essential building blocks that make life possible. You'll discover how simple monomers join together like LEGO bricks to create...

Building Blocks of Life: Monomers and Polymers
Think of biological molecules like construction sets - monomers are the individual bricks, whilst polymers are the finished structures built from identical pieces joined together. This simple concept explains how your body creates everything from energy stores to muscle fibres.
Two key reactions control this molecular construction site. Condensation reactions join monomers together by removing water molecules, like welding pieces with the loss of steam. Hydrolysis reactions do the opposite - they break apart large molecules by adding water back, which is exactly what happens when you digest food.
Carbohydrates follow the CHO formula and serve as your body's primary energy source. Monosaccharides like glucose are single sugar units that dissolve easily in blood for quick transport around your body.
Quick Tip: Remember that alpha glucose (used in starch) has hydrogen above the first carbon, whilst beta glucose (used in cellulose) has the OH group above - this tiny difference completely changes their properties!

Sugar Chemistry: From Simple to Complex
Ribose and deoxyribose might sound complicated, but they're just five-carbon sugars with a crucial difference. Ribose (in RNA) keeps all its OH groups, whilst deoxyribose (in DNA) loses one oxygen atom - making DNA more stable for long-term information storage.
When two monosaccharides join through condensation reactions, they form glycosidic bonds and create disaccharides like table sugar. These double sugars remain soluble and sweet, perfect for quick energy hits.
Polysaccharides are the heavy-duty storage units - long chains of sugars linked by glycosidic bonds. Most are insoluble due to their massive, branched structures, which makes them ideal for storing energy without affecting your cells' water balance.
Exam Focus: Each glycosidic bond formation releases one water molecule - count the bonds to work out how much water is produced in synthesis reactions!

Energy Storage: Starch and Its Components
Plants face the same problem you do - they need to store excess energy for later use. Starch solves this perfectly by being completely insoluble, so it won't mess with the plant's water balance while storing massive amounts of glucose.
Amylose forms unbranched chains that coil into tight spirals, packing efficiently like a compressed spring. Its compact structure makes it brilliant for storage but slow to break down. Amylopectin takes a different approach with its branched design, allowing enzymes to attack multiple points simultaneously for faster glucose release.
The branching happens through different bond types - straight sections use 1-4 glycosidic bonds, whilst branch points use 1-6 bonds. This creates a tree-like structure that balances storage efficiency with accessibility.
Memory Trick: Amylose = "A-my-coiled" (coiled structure), Amylopectin = "A-my-branches" (branched structure)!

Animal Storage and Structure: Glycogen and Cellulose
Glycogen is basically amylopectin on steroids - it has branches every 8-12 glucose units compared to starch's longer straight sections. This ultra-branched structure reflects animals' higher metabolic demands and need for rapid energy release during movement.
Cellulose breaks all the rules by using beta glucose, creating straight, unbranched chains where every other glucose molecule flips 180°. This alternating pattern allows adjacent molecules to form hydrogen bonds, creating rope-like microfibrils of incredible strength.
Triglycerides represent a completely different storage strategy. Made from glycerol plus three fatty acids joined by ester bonds, they pack almost twice the energy of carbohydrates. Their hydrophobic nature means they won't absorb water and swell up like a sponge.
Real-world Connection: Cellulose's strength-to-weight ratio rivals steel - that's why it's perfect for plant cell walls and why we use it to make paper!

Fats and Membrane Structure
Saturated fatty acids pack together tightly like straight pencils in a box, whilst unsaturated fatty acids have kinks from double bonds that push molecules apart. More kinks mean lower melting points - think of butter (saturated) versus olive oil (unsaturated) at room temperature.
Phospholipids are the molecular architects of cell membranes. With hydrophilic phosphate heads and hydrophobic fatty acid tails, they automatically arrange into bilayers - the heads face outward toward water whilst the tails hide inside.
This bilayer structure creates a selectively permeable barrier. Small, non-polar molecules can slip through the fatty acid centre, but water-soluble substances get blocked. It's like having a security system that only lets certain molecules pass.
Visual Learning: Picture phospholipids as matchsticks with magnetic heads - they'll always orient themselves with heads touching water and tails clustering together!

Membrane Fluidity and Protein Basics
Cholesterol acts like a membrane thermostat, keeping cell membranes at just the right consistency. In hot conditions, it prevents excessive fluidity; in cold conditions, it stops the membrane from becoming too rigid and cracking.
Proteins are the workhorses of your cells, built from chains of amino acids linked by peptide bonds. Each amino acid has the same basic structure except for its R group - this variable side chain gives each amino acid its unique personality.
The condensation reaction between amino acids is straightforward: the hydrogen from one amino acid's amine group combines with the hydroxyl group from another's carboxyl group, releasing water and forming a covalent peptide bond.
Study Strategy: Focus on the R groups when learning amino acids - they determine everything about how the protein will fold and function!

Protein Bonds and Structure Levels
Four types of bonds hold proteins in their final shapes. Hydrogen bonds form between slightly charged atoms but break easily with heat. Ionic bonds create strong attractions between oppositely charged R groups. Disulfide bridges form the strongest covalent bonds between sulfur-containing amino acids.
Primary structure is simply the sequence of amino acids - change even one, and you change the entire protein. Secondary structure introduces basic folding patterns like alpha helixes (tight spirals) and beta pleated sheets (parallel chains with hydrogen bonds between them).
Tertiary structure creates the final 3D shape through complex interactions between R groups. Hydrophobic R groups cluster inward whilst hydrophilic ones face outward, stabilised by all four bond types working together.
Exam Essential: Temperature and pH changes break hydrogen bonds first, which is why proteins denature (lose their shape) when you cook them!

Protein Folding and Quaternary Structure
Quaternary structure only exists in proteins with multiple polypeptide chains, called subunits. Each subunit has its own tertiary structure, but they work together like different instruments in an orchestra to create the protein's final function.
The four structural levels build upon each other logically. Primary determines secondary, secondary influences tertiary, and tertiary affects how multiple chains interact in quaternary structures. It's like following a recipe where each step depends on getting the previous one right.
Understanding these levels helps explain why protein folding is so critical. A single amino acid change in the primary structure can cascade through all levels, potentially destroying the protein's function - this is what happens in genetic diseases like sickle cell anemia.
Connection Point: Computer modelling now predicts protein shapes from amino acid sequences, revolutionising drug design by showing how medicines might interact with target proteins!

Globular Proteins: Specialists in Action
Globular proteins are the specialists of the protein world - compact, spherical, and designed for specific jobs. Their hydrophilic R groups face outward for solubility, whilst hydrophobic groups cluster inside, making them perfect for transport in body fluids.
Haemoglobin exemplifies sophisticated protein design with four polypeptide chains, each carrying an iron-containing haem group. This quaternary structure allows cooperative oxygen binding - when one chain grabs oxygen, it makes the others more likely to bind too.
Insulin and pepsin show globular proteins' versatility. Insulin's compact, soluble structure lets it travel through blood to regulate glucose levels, whilst pepsin's stable tertiary structure survives stomach acid to digest other proteins.
Key Insight: Prosthetic groups like haem aren't made of amino acids but are essential for protein function - removing iron from haemoglobin makes it useless for oxygen transport!

Fibrous Proteins: The Body's Construction Materials
Fibrous proteins are your body's building materials - long, strong, and perfectly designed for structural roles. Their repetitive sequences and cross-linked chains create incredible tensile strength, like biological steel cables.
Collagen forms the framework for skin, tendons, and bones. Its flexibility allows movement whilst providing strength, and its ability to bind minerals makes it essential for bone formation. Keratin varies from flexible (skin) to rigid (nails) depending on how many disulfide bridges cross-link its structure.
Elastin solves the problem of tissues that need to stretch and spring back. Found in skin, blood vessels, and lung tissue, it allows these structures to expand under pressure then return to their original size.
Real-world Application: Understanding collagen structure helps explain why vitamin C deficiency causes scurvy - without it, collagen can't form properly, leading to weak connective tissues!
We thought you’d never ask...
Similar content
Most popular content: Proteins
4A-Level Biology Active Recall
Enhance your understanding of A-Level OCR Biology with this comprehensive active recall resource. Covering key concepts such as cell structure, enzyme function, and ecological interactions, this study material is designed to reinforce your knowledge and improve exam performance. Ideal for revision and self-assessment.
Understanding Protein Structures
Explore the four levels of protein structure: primary, secondary, tertiary, and quaternary. This detailed summary covers key concepts such as peptide bonds, hydrogen bonds, and the differences between globular and fibrous proteins. Ideal for A Level Biology students preparing for exams.
TOPIC 1: A-Level Biology
Topic 1 (Biological Molecules, More Biological Molecules) for A-Level Biology
Proteins
Paper 1. What is a protein? What it’s structure? What are types of bonding involved? How to test for proteins? Globular VS Fibrous. Haemoglobin VS Collagen.
Most popular content in Biology
9Cell Biology and Cell structure
cell structures
The functions of subcellular structures - B1 Biology
Flashcards on the different functions of subcellular structures: cell membrane, nucleus, mitochondria, ribosomes, cytoplasm, permant vacuole, chloroplasts and cell wall.
1.cells Gcse biology question cards
combined science higher biology
AQA Biology: Key Concepts
Explore essential AQA Biology topics including Photosynthesis, Respiration, Homeostasis, Genetics, and Ecology. This comprehensive knowledge organizer covers key concepts such as energy transfer, hormonal control, and genetic variation, providing a solid foundation for your studies. Ideal for exam preparation and understanding biological processes.
Biology Paper 1 quiz
this is a simple quiz on key knowledge needed for paper 1
Types of cells
biology
A-Level Biology Year 1 Overview
Comprehensive summary of AQA A-Level Biology Year 1, covering key topics such as cellular structure, protein synthesis, immune response, gas exchange, and more. Ideal for exam preparation and understanding biological concepts. Includes detailed insights into cellular processes, biological classification, and the circulatory system.
biology paper 1
all notes
biology paper 1
these are some exam questions for biology paper which are more likely to come up in exams
Most popular content
9Sociology of Education Overview
Explore comprehensive A-Level Sociology notes on the education system, covering key theories, policies, and sociological perspectives. This resource includes insights on marketisation, gender roles, cultural deprivation, and educational inequalities, providing a thorough understanding of how education shapes social stratification and individual achievement. Ideal for exam preparation and in-depth study.
Sociology of Families: Comprehensive Revision
Dive into an extensive overview of family dynamics, perspectives, and patterns in sociology. This resource covers key concepts such as family diversity, gender roles, marriage, and the impact of social policies on family structures. Perfect for A-Level Sociology students preparing for Paper 2.
Criminology: Crime & Punishment Overview
Comprehensive mindmaps covering key concepts in the Crime and Punishment topic for WJEC Criminology Unit 4. This resource includes detailed insights into the Criminal Justice System, crime prevention strategies, sentencing models, and the roles of various agencies. Ideal for A-Level revision, ensuring you grasp essential theories and legislative processes to excel in your exams.
Comprehensive Crime & Deviance Overview
Explore an extensive revision of crime and deviance topics, including theories, types of crime, and the impact of media. This resource covers key concepts such as Marxism, functionalism, gender and crime, and the influence of globalization on criminal behavior. Ideal for students seeking a thorough understanding of criminology and its various theories. Type: Full Topic Revision.
Cell Biology and Cell structure
cell structures
WJEC Unit 4 Criminology
Criminology unit 4 detailed revision note
Sociological Theories Overview
Comprehensive revision of key sociological theories including Functionalism, Marxism, Feminism, and Interpretivism. Explore concepts like value freedom, identity formation, and the critique of social control. Ideal for AQA A-Level Sociology students preparing for exams. This summary covers essential theories and their implications in sociology, providing a clear understanding of each perspective.
The functions of subcellular structures - B1 Biology
Flashcards on the different functions of subcellular structures: cell membrane, nucleus, mitochondria, ribosomes, cytoplasm, permant vacuole, chloroplasts and cell wall.
1.cells Gcse biology question cards
combined science higher biology
Students love us — and so will you.
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.
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.
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.