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
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Britain & the wider world: 1745 -1901
1l the quest for political stability: germany, 1871-1991
The cold war
Inter-war germany
Medieval period: 1066 -1509
2d religious conflict and the church in england, c1529-c1570
2o democracy and nazism: germany, 1918-1945
1f industrialisation and the people: britain, c1783-1885
1c the tudors: england, 1485-1603
2m wars and welfare: britain in transition, 1906-1957
World war two & the holocaust
2n revolution and dictatorship: russia, 1917-1953
2s the making of modern britain, 1951-2007
World war one
Britain: 1509 -1745
Show all topics
Biology
7 Dec 2025
64
5 pages
Darcy Smyth @darcysmyth_aadg
B1-B4 Biology covers the fundamental concepts of how living things work, from the tiny cells that make up... Show more
Every living thing is built from cells - think of them as biological building blocks with specific parts doing different jobs. Animal cells have a nucleus (containing genetic material), cytoplasm (full of enzymes), cell membrane (controlling what enters and exits), and mitochondria (powering the cell through respiration).
Plant cells have all these parts plus some extras a cell wall for support, a vacuole filled with cell sap, and chloroplasts for photosynthesis. Some cells, like stem cells found in bone marrow, haven't specialised yet and can become any type of cell - that's why they're so useful in medicine.
Substances move around cells through different processes. Diffusion happens when particles spread from areas of high concentration to low concentration naturally. Osmosis is similar but specifically for water moving across membranes. Active transport is different - it moves molecules against the concentration gradient, which requires energy from the cell.
Quick Tip Remember that plant cells have everything animal cells have, PLUS extra structures - never the other way around!
Your body's organs are perfectly designed for their jobs through specialised exchange surfaces. The lungs have tiny air sacs called alveoli with huge surface areas and thin walls for efficient gas exchange. Your small intestine has villi - finger-like projections that massively increase surface area for absorbing nutrients quickly.
Enzymes are biological catalysts that speed up reactions without being used up themselves. The main digestive enzymes you need to know are amylase (breaks down starch into sugars), protease (breaks down proteins into amino acids), and lipase (breaks down fats into glycerol and fatty acids).
Your heart pumps blood around your body through three types of blood vessels. Arteries carry blood away from the heart, veins carry blood back to the heart, and capillaries are tiny vessels where substances are exchanged with tissues.
Exam Focus Learn the enzyme names and what they break down - this comes up frequently in tests!
Pathogens are microorganisms that cause disease, and they come in four main types. Bacteria reproduce rapidly and release toxins, viruses live inside cells and damage them, fungi grow and spread on organisms, and protists are parasites that live off other organisms.
Your body has brilliant defence mechanisms against disease. Physical barriers like skin, hair, and mucus stop pathogens entering. If they do get in, white blood cells either consume the invaders or produce antibodies that attack specific pathogens.
Vaccination works by injecting small amounts of dead or inactive pathogens, making your immune system familiar with the disease so it can fight it off quickly if you encounter it again. Antibiotics kill bacteria but don't work against viruses - that's why doctors won't give them for colds or flu.
Real World Antibiotic-resistant bacteria develop when people don't complete their antibiotic courses, so always finish the full prescription!
Respiration happens in every living cell to transfer energy from glucose - it's how your body powers everything from muscle contractions to maintaining body temperature. Aerobic respiration uses oxygen and happens in the mitochondria, whilst anaerobic respiration happens without oxygen but only provides energy for short periods.
Photosynthesis is how plants make their own food using the equation 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂. Plants use the glucose produced for respiration, making cellulose for structure, or storing it as starch for later.
The rate of photosynthesis depends on limiting factors - whichever factor is in shortest supply limits the whole process. These are light intensity, carbon dioxide concentration, and temperature. Farmers use greenhouses to control these factors and maximise crop growth.
Memory Trick Photosynthesis and respiration are basically opposite processes - one makes glucose using CO₂, the other breaks down glucose producing CO₂!
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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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
Darcy Smyth
@darcysmyth_aadg
B1-B4 Biology covers the fundamental concepts of how living things work, from the tiny cells that make up everything to the complex processes that keep organisms alive. You'll explore how substances move in and out of cells, how organs are... Show more
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Every living thing is built from cells - think of them as biological building blocks with specific parts doing different jobs. Animal cells have a nucleus (containing genetic material), cytoplasm (full of enzymes), cell membrane (controlling what enters and exits), and mitochondria (powering the cell through respiration).
Plant cells have all these parts plus some extras: a cell wall for support, a vacuole filled with cell sap, and chloroplasts for photosynthesis. Some cells, like stem cells found in bone marrow, haven't specialised yet and can become any type of cell - that's why they're so useful in medicine.
Substances move around cells through different processes. Diffusion happens when particles spread from areas of high concentration to low concentration naturally. Osmosis is similar but specifically for water moving across membranes. Active transport is different - it moves molecules against the concentration gradient, which requires energy from the cell.
Quick Tip: Remember that plant cells have everything animal cells have, PLUS extra structures - never the other way around!
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Your body's organs are perfectly designed for their jobs through specialised exchange surfaces. The lungs have tiny air sacs called alveoli with huge surface areas and thin walls for efficient gas exchange. Your small intestine has villi - finger-like projections that massively increase surface area for absorbing nutrients quickly.
Enzymes are biological catalysts that speed up reactions without being used up themselves. The main digestive enzymes you need to know are amylase (breaks down starch into sugars), protease (breaks down proteins into amino acids), and lipase (breaks down fats into glycerol and fatty acids).
Your heart pumps blood around your body through three types of blood vessels. Arteries carry blood away from the heart, veins carry blood back to the heart, and capillaries are tiny vessels where substances are exchanged with tissues.
Exam Focus: Learn the enzyme names and what they break down - this comes up frequently in tests!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Pathogens are microorganisms that cause disease, and they come in four main types. Bacteria reproduce rapidly and release toxins, viruses live inside cells and damage them, fungi grow and spread on organisms, and protists are parasites that live off other organisms.
Your body has brilliant defence mechanisms against disease. Physical barriers like skin, hair, and mucus stop pathogens entering. If they do get in, white blood cells either consume the invaders or produce antibodies that attack specific pathogens.
Vaccination works by injecting small amounts of dead or inactive pathogens, making your immune system familiar with the disease so it can fight it off quickly if you encounter it again. Antibiotics kill bacteria but don't work against viruses - that's why doctors won't give them for colds or flu.
Real World: Antibiotic-resistant bacteria develop when people don't complete their antibiotic courses, so always finish the full prescription!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Respiration happens in every living cell to transfer energy from glucose - it's how your body powers everything from muscle contractions to maintaining body temperature. Aerobic respiration uses oxygen and happens in the mitochondria, whilst anaerobic respiration happens without oxygen but only provides energy for short periods.
Photosynthesis is how plants make their own food using the equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂. Plants use the glucose produced for respiration, making cellulose for structure, or storing it as starch for later.
The rate of photosynthesis depends on limiting factors - whichever factor is in shortest supply limits the whole process. These are light intensity, carbon dioxide concentration, and temperature. Farmers use greenhouses to control these factors and maximise crop growth.
Memory Trick: Photosynthesis and respiration are basically opposite processes - one makes glucose using CO₂, the other breaks down glucose producing CO₂!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
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.
1
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Quotes from every main character
English LiteratureApp 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