Subjects
Maths
Chemistry
Biology
English Language
History
Responding to change (a2 only)
Infection and response
Homeostasis and response
Energy transfers (a2 only)
Cell biology
Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
Organisation
Substance exchange
Bioenergetics
Genetic information & variation
Inheritance, variation and evolution
Genetics & ecosystems (a2 only)
Ecology
Cells
Show all topics
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
Show all topics
Biology
13 Dec 2025
103
2 pages
Ali @ali_wnmq
Your digestive system is like a brilliant factory that breaks down your food into tiny bits your body... Show more
Ever wondered how your body turns a sandwich into energy? Your digestive system has two main jobs breaking food down into small, soluble molecules and absorbing these nutrients into your bloodstream.
Enzymes are the real stars here - they're incredibly picky workers! Each enzyme has a uniquely shaped active site that only fits one specific substrate, like a lock and key. This is why enzymes are so specific - only the right molecule can fit.
The lock and key model explains this perfectly the substrate locks into the enzyme's active site because they have complementary shapes. The enzyme then breaks the bonds in the substrate, creating products that no longer fit the active site, so they leave and the enzyme can work again.
Quick Tip Remember that enzymes are reusable - they don't get used up in the reaction, which is why your body doesn't need massive amounts of them!
Different organs produce different enzymes. Amylase (breaks down starch into glucose) comes from your salivary glands, pancreas, and small intestine. Protease (breaks proteins into amino acids) is made in your stomach, pancreas, and small intestine. Lipase (breaks fats into fatty acids and glycerol) is produced by your pancreas and small intestine.
Bile might not be glamorous, but it's essential! Made in your liver and stored in your gall bladder, bile has two crucial functions that help digestion work smoothly.
First, bile is alkaline, so it neutralises the hydrochloric acid from your stomach - this creates the right pH for enzymes to work in your small intestine. Second, bile emulsifies fats, breaking them into tiny droplets that massively increase the surface area for lipase to work on.
Now for the practical stuff you'll definitely see in exams - food tests! For sugars, use Benedict's solution, heat to 80°C for 5 minutes, and watch for colour changes from blue to green/orange/red. Testing for starch is simpler add iodine solution and look for a blue-black colour change from the original orange-brown.
Exam Alert These food tests are common practical questions - make sure you know the exact colours and temperatures!
The protein test uses Biuret reagent - a positive result changes the solution from blue to purple or lilac. These tests are brilliant for identifying what nutrients are present in different foods, and you'll likely need to describe them step-by-step in your exams.
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.
2
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the intricate workings of biological systems, including the circulatory and digestive systems. This summary covers key concepts such as heart structure, blood components, enzyme functions, and the role of digestive enzymes in nutrient absorption. Ideal for students seeking a comprehensive understanding of biology organization.
BiologyExplore the essential roles of enzymes in digestion and cell organization. This summary covers key concepts such as enzyme function, the digestive process, and the impact of temperature and pH on enzyme activity. Ideal for students studying biology, this resource includes a mind map and a detailed table for easy reference.
BiologyExplore the role of digestive enzymes in breaking down food into absorbable molecules. This summary covers key enzymes like amylase, protease, and lipase, their sites of production (salivary glands, pancreas, small intestine), and the reactions they catalyze. Ideal for students studying biology and human digestion.
BiologyExplore the intricate roles of enzymes and the digestive system in human physiology. This summary covers key concepts such as protein structure, enzyme function, metabolic reactions, and the digestion of carbohydrates, proteins, and lipids. Understand how enzymes act as biological catalysts and the importance of pH and temperature in enzyme activity. Ideal for AQA B3 curriculum.
BiologyExplore the intricate process of human digestion, from the mouth to the large intestine. This summary covers key concepts such as digestive enzymes, nutrient absorption, and the roles of various organs in the digestive system. Ideal for GCSE biology students seeking a clear understanding of how food is processed in the body.
BiologyExplore the role of enzymes as biological catalysts in digestion, including the lock and key model, factors affecting enzyme activity, and the digestive process. This summary covers key concepts such as enzyme-substrate complexes, optimal conditions for enzyme function, and the digestive system's organization. Ideal for AQA GCSE Biology revision.
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
Ali
@ali_wnmq
Your digestive system is like a brilliant factory that breaks down your food into tiny bits your body can actually use. Understanding how enzymes work and what happens to different nutrients is crucial for your biology exams - and it's... Show more
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Ever wondered how your body turns a sandwich into energy? Your digestive system has two main jobs: breaking food down into small, soluble molecules and absorbing these nutrients into your bloodstream.
Enzymes are the real stars here - they're incredibly picky workers! Each enzyme has a uniquely shaped active site that only fits one specific substrate, like a lock and key. This is why enzymes are so specific - only the right molecule can fit.
The lock and key model explains this perfectly: the substrate locks into the enzyme's active site because they have complementary shapes. The enzyme then breaks the bonds in the substrate, creating products that no longer fit the active site, so they leave and the enzyme can work again.
Quick Tip: Remember that enzymes are reusable - they don't get used up in the reaction, which is why your body doesn't need massive amounts of them!
Different organs produce different enzymes. Amylase (breaks down starch into glucose) comes from your salivary glands, pancreas, and small intestine. Protease (breaks proteins into amino acids) is made in your stomach, pancreas, and small intestine. Lipase (breaks fats into fatty acids and glycerol) is produced by your pancreas and small intestine.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Bile might not be glamorous, but it's essential! Made in your liver and stored in your gall bladder, bile has two crucial functions that help digestion work smoothly.
First, bile is alkaline, so it neutralises the hydrochloric acid from your stomach - this creates the right pH for enzymes to work in your small intestine. Second, bile emulsifies fats, breaking them into tiny droplets that massively increase the surface area for lipase to work on.
Now for the practical stuff you'll definitely see in exams - food tests! For sugars, use Benedict's solution, heat to 80°C for 5 minutes, and watch for colour changes from blue to green/orange/red. Testing for starch is simpler: add iodine solution and look for a blue-black colour change from the original orange-brown.
Exam Alert: These food tests are common practical questions - make sure you know the exact colours and temperatures!
The protein test uses Biuret reagent - a positive result changes the solution from blue to purple or lilac. These tests are brilliant for identifying what nutrients are present in different foods, and you'll likely need to describe them step-by-step in your exams.
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.
2
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the intricate workings of biological systems, including the circulatory and digestive systems. This summary covers key concepts such as heart structure, blood components, enzyme functions, and the role of digestive enzymes in nutrient absorption. Ideal for students seeking a comprehensive understanding of biology organization.
BiologyExplore the essential roles of enzymes in digestion and cell organization. This summary covers key concepts such as enzyme function, the digestive process, and the impact of temperature and pH on enzyme activity. Ideal for students studying biology, this resource includes a mind map and a detailed table for easy reference.
BiologyExplore the role of digestive enzymes in breaking down food into absorbable molecules. This summary covers key enzymes like amylase, protease, and lipase, their sites of production (salivary glands, pancreas, small intestine), and the reactions they catalyze. Ideal for students studying biology and human digestion.
BiologyExplore the intricate roles of enzymes and the digestive system in human physiology. This summary covers key concepts such as protein structure, enzyme function, metabolic reactions, and the digestion of carbohydrates, proteins, and lipids. Understand how enzymes act as biological catalysts and the importance of pH and temperature in enzyme activity. Ideal for AQA B3 curriculum.
BiologyExplore the intricate process of human digestion, from the mouth to the large intestine. This summary covers key concepts such as digestive enzymes, nutrient absorption, and the roles of various organs in the digestive system. Ideal for GCSE biology students seeking a clear understanding of how food is processed in the body.
BiologyExplore the role of enzymes as biological catalysts in digestion, including the lock and key model, factors affecting enzyme activity, and the digestive process. This summary covers key concepts such as enzyme-substrate complexes, optimal conditions for enzyme function, and the digestive system's organization. Ideal for AQA GCSE Biology revision.
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