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
9 Dec 2025
292
6 pages
Lexi @lexi_revision
Ever wondered what makes you different from a plant or why bacteria can survive almost anywhere? It all... Show more
Think of cells as microscopic factories - each part has a specific job that keeps life running smoothly. Animal cells and plant cells share some common features, but plants have evolved extra structures to help them survive as stationary organisms.
Both types of cells contain a nucleus (the control centre), cytoplasm (where chemical reactions happen), cell membrane (the boundary), mitochondria (powerhouses), and ribosomes (protein makers). These are the essential components that every complex cell needs to function.
Plant cells have three additional structures that animals don't need chloroplasts for photosynthesis, a cell wall for extra support, and a large permanent vacuole for structural strength.
Quick Tip Remember that animal cells are more flexible because they don't have rigid cell walls - that's why we can move around whilst plants stay rooted!
Animal cells are like streamlined machines designed for movement and quick responses. The cell membrane acts as a selective barrier, controlling what enters and leaves the cell - think of it as a bouncer at a club.
The nucleus contains all the genetic information (DNA) and controls everything the cell does. It's surrounded by cytoplasm, a jelly-like substance where most chemical reactions occur. Mitochondria are the cell's power stations, releasing energy from glucose during respiration.
Ribosomes are tiny structures that make proteins - they're like molecular assembly lines. These proteins are essential for growth, repair, and all the chemical reactions that keep you alive.
Exam Focus You need to know both the structure names AND their functions - examiners love asking "What is the function of...?"
Plant cells have everything animal cells have, plus some brilliant extras that help them survive without being able to move around. Chloroplasts contain chlorophyll, which traps light energy for photosynthesis - basically turning sunlight into food.
The cell wall made of cellulose provides crucial structural support. Unlike the flexible cell membrane, this rigid wall prevents the cell from bursting when water enters. It's like having both a balloon (membrane) and a protective box (wall) around the cell contents.
The permanent vacuole is filled with cell sap and pushes against the cell wall, making the cell rigid and strong. This is why plants can grow tall without having bones - their cell structure provides all the support they need.
Memory Trick Plants need extra support because they can't run away from problems - so they evolved tougher structures!
Bacterial cells are completely different from plant and animal cells - they're much simpler and don't have a proper nucleus. Instead, they have a circular chromosome floating freely in the cytoplasm, plus small rings of DNA called plasmids.
Bacteria have a non-cellulose cell wall for protection and a cell membrane for control, but no mitochondria or other complex structures. This simplicity actually makes them incredibly successful - they can reproduce rapidly and survive in extreme conditions.
Light microscopes let us see these tiny structures using lenses and light. The objective lens (near the specimen) and eyepiece lens work together to magnify images. We use chemical stains like iodine for plant cells and methylene blue for animal cells to make structures more visible.
Practical Tip Always start with the lowest magnification and work your way up - it's much easier to find your specimen this way!
When preparing microscope slides, technique matters enormously. Start by placing your specimen flat on the slide, add a drop of stain (like iodine), then carefully lower the coverslip to avoid air bubbles - they'll ruin your view.
Magnification calculations are straightforward Image size = Actual size × Magnification. Remember that 1mm equals 1,000 micrometers (μm) - most cells are measured in micrometers because they're incredibly small.
Diffusion is a crucial process where particles naturally move from areas of high concentration to low concentration - like perfume spreading across a room. Stem cells are unspecialised cells that can develop into any type of cell, making them incredibly valuable for medical research and treatment.
Calculation Hack Always convert units first in magnification problems - it'll save you marks in exams!
Stem cell research sparks heated debates because it involves real ethical dilemmas. Supporters argue that stem cells can save lives by growing replacement tissues and organs, potentially curing diabetes, spinal injuries, and stroke damage. Since excess IVF embryos are destroyed anyway, why not use them for life-saving research?
Critics believe that destroying embryos for research is morally wrong, regardless of the potential benefits. This isn't just a scientific issue - it touches on fundamental questions about when life begins and what we're willing to do to help others.
Government committees include scientific advisers who understand both the incredible potential and current limitations of stem cell research. They help navigate the complex ethical scenarios that arise when cutting-edge science meets moral concerns.
Exam Strategy Be prepared to discuss both sides of the stem cell debate - examiners want to see you understand the complexity, not just pick a side!
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.
5
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the essential role of Adenosine Triphosphate (ATP) in cellular respiration and photosynthesis. This summary covers ATP hydrolysis, its function as an immediate energy source, and its importance in various cellular processes such as muscle contraction and active transport. Understand why ATP is not an energy storage molecule and how it is continuously synthesized to meet cellular demands.
BiologyExplore the key differences between eukaryotic and prokaryotic cells, including their structures and functions. This summary covers essential components such as the nucleus, mitochondria, chloroplasts, and more, providing a clear understanding of cellular biology. Ideal for students studying cellular structure and functions.
BiologyExplore the essential components of plant and animal cells, including the cell wall, nucleus, cytoplasm, and mitochondria. This summary provides a clear overview of cell structures, their functions, and the differences between plant and animal cells, perfect for Year 7 revision. Ideal for students preparing for exams.
Biologyscience biology revision cards
BiologyExplore the key sub-cellular structures of plant cells, including the cell membrane, cell wall, vacuole, cytoplasm, chloroplasts, and nucleus. Understand their functions such as support, protection, storage, and photosynthesis in this informative summary.
BiologyExplore the essential sub-cellular structures including the cell membrane, cytoplasm, nucleus, cell wall, chloroplasts, and permanent vacuole. This summary highlights their functions and locations in different cell types, providing a clear understanding of cellular organization. Ideal for biology students studying cell structure and function.
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
Lexi
@lexi_revision
Ever wondered what makes you different from a plant or why bacteria can survive almost anywhere? It all comes down to cells - the tiny building blocks that make up every living thing. Understanding cell structure is crucial for GCSE... Show more
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Think of cells as microscopic factories - each part has a specific job that keeps life running smoothly. Animal cells and plant cells share some common features, but plants have evolved extra structures to help them survive as stationary organisms.
Both types of cells contain a nucleus (the control centre), cytoplasm (where chemical reactions happen), cell membrane (the boundary), mitochondria (powerhouses), and ribosomes (protein makers). These are the essential components that every complex cell needs to function.
Plant cells have three additional structures that animals don't need: chloroplasts for photosynthesis, a cell wall for extra support, and a large permanent vacuole for structural strength.
Quick Tip: Remember that animal cells are more flexible because they don't have rigid cell walls - that's why we can move around whilst plants stay rooted!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Animal cells are like streamlined machines designed for movement and quick responses. The cell membrane acts as a selective barrier, controlling what enters and leaves the cell - think of it as a bouncer at a club.
The nucleus contains all the genetic information (DNA) and controls everything the cell does. It's surrounded by cytoplasm, a jelly-like substance where most chemical reactions occur. Mitochondria are the cell's power stations, releasing energy from glucose during respiration.
Ribosomes are tiny structures that make proteins - they're like molecular assembly lines. These proteins are essential for growth, repair, and all the chemical reactions that keep you alive.
Exam Focus: You need to know both the structure names AND their functions - examiners love asking "What is the function of...?"
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Plant cells have everything animal cells have, plus some brilliant extras that help them survive without being able to move around. Chloroplasts contain chlorophyll, which traps light energy for photosynthesis - basically turning sunlight into food.
The cell wall made of cellulose provides crucial structural support. Unlike the flexible cell membrane, this rigid wall prevents the cell from bursting when water enters. It's like having both a balloon (membrane) and a protective box (wall) around the cell contents.
The permanent vacuole is filled with cell sap and pushes against the cell wall, making the cell rigid and strong. This is why plants can grow tall without having bones - their cell structure provides all the support they need.
Memory Trick: Plants need extra support because they can't run away from problems - so they evolved tougher structures!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Bacterial cells are completely different from plant and animal cells - they're much simpler and don't have a proper nucleus. Instead, they have a circular chromosome floating freely in the cytoplasm, plus small rings of DNA called plasmids.
Bacteria have a non-cellulose cell wall for protection and a cell membrane for control, but no mitochondria or other complex structures. This simplicity actually makes them incredibly successful - they can reproduce rapidly and survive in extreme conditions.
Light microscopes let us see these tiny structures using lenses and light. The objective lens (near the specimen) and eyepiece lens work together to magnify images. We use chemical stains like iodine for plant cells and methylene blue for animal cells to make structures more visible.
Practical Tip: Always start with the lowest magnification and work your way up - it's much easier to find your specimen this way!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
When preparing microscope slides, technique matters enormously. Start by placing your specimen flat on the slide, add a drop of stain (like iodine), then carefully lower the coverslip to avoid air bubbles - they'll ruin your view.
Magnification calculations are straightforward: Image size = Actual size × Magnification. Remember that 1mm equals 1,000 micrometers (μm) - most cells are measured in micrometers because they're incredibly small.
Diffusion is a crucial process where particles naturally move from areas of high concentration to low concentration - like perfume spreading across a room. Stem cells are unspecialised cells that can develop into any type of cell, making them incredibly valuable for medical research and treatment.
Calculation Hack: Always convert units first in magnification problems - it'll save you marks in exams!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Stem cell research sparks heated debates because it involves real ethical dilemmas. Supporters argue that stem cells can save lives by growing replacement tissues and organs, potentially curing diabetes, spinal injuries, and stroke damage. Since excess IVF embryos are destroyed anyway, why not use them for life-saving research?
Critics believe that destroying embryos for research is morally wrong, regardless of the potential benefits. This isn't just a scientific issue - it touches on fundamental questions about when life begins and what we're willing to do to help others.
Government committees include scientific advisers who understand both the incredible potential and current limitations of stem cell research. They help navigate the complex ethical scenarios that arise when cutting-edge science meets moral concerns.
Exam Strategy: Be prepared to discuss both sides of the stem cell debate - examiners want to see you understand the complexity, not just pick a side!
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.
5
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the essential role of Adenosine Triphosphate (ATP) in cellular respiration and photosynthesis. This summary covers ATP hydrolysis, its function as an immediate energy source, and its importance in various cellular processes such as muscle contraction and active transport. Understand why ATP is not an energy storage molecule and how it is continuously synthesized to meet cellular demands.
BiologyExplore the key differences between eukaryotic and prokaryotic cells, including their structures and functions. This summary covers essential components such as the nucleus, mitochondria, chloroplasts, and more, providing a clear understanding of cellular biology. Ideal for students studying cellular structure and functions.
BiologyExplore the essential components of plant and animal cells, including the cell wall, nucleus, cytoplasm, and mitochondria. This summary provides a clear overview of cell structures, their functions, and the differences between plant and animal cells, perfect for Year 7 revision. Ideal for students preparing for exams.
Biologyscience biology revision cards
BiologyExplore the key sub-cellular structures of plant cells, including the cell membrane, cell wall, vacuole, cytoplasm, chloroplasts, and nucleus. Understand their functions such as support, protection, storage, and photosynthesis in this informative summary.
BiologyExplore the essential sub-cellular structures including the cell membrane, cytoplasm, nucleus, cell wall, chloroplasts, and permanent vacuole. This summary highlights their functions and locations in different cell types, providing a clear understanding of cellular organization. Ideal for biology students studying cell structure and function.
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