Your body is made up of trillions of cells, but... Show more
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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
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566
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3 Dec 2025
•
ellie
@ellili.7
Your body is made up of trillions of cells, but... Show more




Plants have their own squad of specialised cells that keep them alive and thriving. These botanical specialists are just as clever as animal cells!
Root hair cells are like tiny underground straws. They grow long, hair-like projections that poke into the soil, massively increasing the surface area for absorption. This clever design means plants can slurp up water and essential mineral ions much more efficiently.
Xylem and phloem cells form the plant's transport network. Think of them as the plant's motorways! Xylem cells are narrow tubes that carry water up from the roots, whilst phloem cells transport food around the plant. Both types join end-to-end like train carriages and have minimal internal structures so liquids can flow freely.
The brilliant thing about plant cells is their flexibility - they can change jobs when needed, unlike most animal cells that are stuck in their chosen career forever.
Top Tip: Remember the transport team - xylem carries water up, phloem carries food around. Think "xylem = H2O express"!

Your body has some seriously clever specialised cells that have evolved perfect designs for their jobs. Let's meet three of the most important ones!
Sperm cells are built like tiny Olympic swimmers. They've got streamlined heads for cutting through water, long tails for propulsion, and are packed with mitochondria for energy. The head even contains special enzymes that work like molecular can-openers to break through the egg cell membrane.
Nerve cells are the body's internet cables - some can be over a metre long! They're designed with branched connections at both ends, creating a massive network that carries electrical signals around your body faster than you can blink.
Muscle cells are the ultimate contractors. They're long and stretchy, giving them plenty of room to contract and relax. Like sperm cells, they're loaded with mitochondria because contracting muscles need loads of energy.
Remember: Each cell's structure perfectly matches its function - form follows function in biology!

Ever wondered how your body creates so many different types of cells? Differentiation is the amazing process where a cell changes to become specialised for a particular job. It's like cells going to university to train for different careers!
Most of this cellular training happens when an organism is developing. Here's the interesting bit: animal cells lose their ability to differentiate quite early in life, whilst plant cells keep this superpower throughout their lives.
In grown-up animals, the few remaining undifferentiated cells (called stem cells) are mainly used as repair crews. They jump into action to replace damaged skin cells when you get a cut or create new blood cells when needed.
Key Point: Think of differentiation as cells choosing their career path - once animal cells pick their job, they're stuck with it, but plant cells can retrain anytime!
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.
App 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
ellie
@ellili.7
Your body is made up of trillions of cells, but they're not all the same! Through a process called differentiation, cells transform themselves into specialised versions that can do specific jobs - from absorbing nutrients to helping you move and... Show more

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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Plants have their own squad of specialised cells that keep them alive and thriving. These botanical specialists are just as clever as animal cells!
Root hair cells are like tiny underground straws. They grow long, hair-like projections that poke into the soil, massively increasing the surface area for absorption. This clever design means plants can slurp up water and essential mineral ions much more efficiently.
Xylem and phloem cells form the plant's transport network. Think of them as the plant's motorways! Xylem cells are narrow tubes that carry water up from the roots, whilst phloem cells transport food around the plant. Both types join end-to-end like train carriages and have minimal internal structures so liquids can flow freely.
The brilliant thing about plant cells is their flexibility - they can change jobs when needed, unlike most animal cells that are stuck in their chosen career forever.
Top Tip: Remember the transport team - xylem carries water up, phloem carries food around. Think "xylem = H2O express"!

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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Your body has some seriously clever specialised cells that have evolved perfect designs for their jobs. Let's meet three of the most important ones!
Sperm cells are built like tiny Olympic swimmers. They've got streamlined heads for cutting through water, long tails for propulsion, and are packed with mitochondria for energy. The head even contains special enzymes that work like molecular can-openers to break through the egg cell membrane.
Nerve cells are the body's internet cables - some can be over a metre long! They're designed with branched connections at both ends, creating a massive network that carries electrical signals around your body faster than you can blink.
Muscle cells are the ultimate contractors. They're long and stretchy, giving them plenty of room to contract and relax. Like sperm cells, they're loaded with mitochondria because contracting muscles need loads of energy.
Remember: Each cell's structure perfectly matches its function - form follows function in biology!

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 creates so many different types of cells? Differentiation is the amazing process where a cell changes to become specialised for a particular job. It's like cells going to university to train for different careers!
Most of this cellular training happens when an organism is developing. Here's the interesting bit: animal cells lose their ability to differentiate quite early in life, whilst plant cells keep this superpower throughout their lives.
In grown-up animals, the few remaining undifferentiated cells (called stem cells) are mainly used as repair crews. They jump into action to replace damaged skin cells when you get a cut or create new blood cells when needed.
Key Point: Think of differentiation as cells choosing their career path - once animal cells pick their job, they're stuck with it, but plant cells can retrain anytime!
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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Explore the process of cell differentiation and specialization in this detailed summary. Learn about various specialized cells, including sperm, nerve, muscle, root hair, phloem, and xylem cells, and their unique functions. Ideal for revision and understanding key concepts in biology.
Explore the key concepts of cell differentiation and specialization in biology. This summary covers the functions of various specialized cells, including root hair cells, muscle cells, nerve cells, and reproductive cells. Understand how cells adapt to perform specific roles and the significance of stem cells in differentiation. Ideal for students studying cell biology.
Explore the fundamental concepts of DNA, including its double helix structure, nucleotide composition, and base pairing rules. This summary covers essential topics for GCSE Biology, focusing on the role of DNA in genetics and molecular biology.
Explore the fundamentals of DNA, chromosomes, and genes in this concise overview. Learn about the double helix structure, the significance of chromosomes, and the role of genes in coding for proteins. Ideal for students studying genetics and biology.
Explore the fundamentals of cell division, including key processes like mitosis, cytokinesis, and the cell cycle. Understand the role of chromosomes, DNA replication, and stem cells in growth and repair. This summary is ideal for GCSE AQA Biology students focusing on Cell Biology.
Explore the process of mitosis and the role of chromosomes in cell division. This summary covers key concepts such as DNA replication, the cell cycle, and the formation of identical daughter cells. Ideal for students studying cell biology and genetics.
App 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