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Eeshal Zulqarnain
11/12/2025
Biology
Cell Biology aqa
47
•
11 Dec 2025
•
Cell Biology AQA Study Guide
Eeshal Zulqarnain
@eeshal_08
1 / 4
Cell Types and Structures
Your body is made up of eukaryotic cells - cells where the genetic material is safely tucked away inside a nucleus. These are much more complex than prokaryotic cells (like bacteria) where the DNA just floats around freely.
Plant and animal cells have some brilliant organelles that keep them running smoothly. Mitochondria are like tiny power stations where respiration happens to give cells energy. Ribosomes act as protein factories, churning out all the proteins your body needs.
Plant cells have extra features that make them special. Chloroplasts contain chlorophyll and handle photosynthesis - basically turning sunlight into food. The cell wall made of cellulose gives plants their strength, whilst the vacuole filled with cell sap helps maintain the plant's shape.
Key Point: Remember that animal cells and plant cells are both eukaryotic, but plant cells have additional structures like chloroplasts and cell walls that animal cells don't have.
Specialised Cells and Microscopy
Different jobs require different tools, and cells are no exception. Sperm cells are perfectly designed for their mission to fertilise an ovum - they're streamlined and packed with mitochondria for energy.
Nerve cells are the body's electrical cables, sending impulses around your body at lightning speed. The myelin coating acts like insulation on a wire, speeding up transmission. Muscle cells contain protein fibres that contract to create movement.
Plant cells have their own specialists too. Root hair cells have tiny hairs that massively increase surface area for absorbing water and nutrients. Xylem cells transport water upwards using thick walls reinforced with lignin, whilst phloem carries sugars both up and down the plant.
When studying cells, electron microscopes give much better magnification and resolution than light microscopes. This means you can see much finer details - essential for understanding how cells actually work.
Key Point: Each specialised cell has specific features that perfectly match its function - form always follows function in biology!
Cell Division and Transport
Bacteria reproduce through binary fission - basically splitting in two. The number of bacteria grows exponentially following the pattern 2ⁿ, which is why bacterial infections can spread so quickly.
Mitosis is how your body grows and repairs itself. The DNA replicates, chromosomes get pulled apart, and one cell becomes two identical cells. This process is crucial for growth, repair, and asexual reproduction.
Stem cells are like biological Swiss Army knives - they're undifferentiated and can become any type of cell. Embryonic stem cells are the most versatile, whilst adult stem cells from bone marrow are more limited but still incredibly useful for medical treatments.
Understanding how substances move in and out of cells is essential. Diffusion moves particles from high to low concentration - think of how oxygen gets into your blood. Osmosis is specifically water moving through membranes, whilst active transport uses energy to move substances against the concentration gradient.
Key Point: The surface area to volume ratio is crucial for diffusion efficiency - smaller cells are generally better at exchanging materials with their environment.
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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.
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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
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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
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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
Cell Biology AQA Study Guide
Eeshal Zulqarnain
@eeshal_08
Ever wondered how your body's cells actually work and what makes them tick? Cell biology is the foundation of understanding how all living things function, from the tiniest bacteria to complex plants and animals like us.
Cell Types and Structures
Your body is made up of eukaryotic cells - cells where the genetic material is safely tucked away inside a nucleus. These are much more complex than prokaryotic cells (like bacteria) where the DNA just floats around freely.
Plant and animal cells have some brilliant organelles that keep them running smoothly. Mitochondria are like tiny power stations where respiration happens to give cells energy. Ribosomes act as protein factories, churning out all the proteins your body needs.
Plant cells have extra features that make them special. Chloroplasts contain chlorophyll and handle photosynthesis - basically turning sunlight into food. The cell wall made of cellulose gives plants their strength, whilst the vacuole filled with cell sap helps maintain the plant's shape.
Key Point: Remember that animal cells and plant cells are both eukaryotic, but plant cells have additional structures like chloroplasts and cell walls that animal cells don't have.
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Specialised Cells and Microscopy
Different jobs require different tools, and cells are no exception. Sperm cells are perfectly designed for their mission to fertilise an ovum - they're streamlined and packed with mitochondria for energy.
Nerve cells are the body's electrical cables, sending impulses around your body at lightning speed. The myelin coating acts like insulation on a wire, speeding up transmission. Muscle cells contain protein fibres that contract to create movement.
Plant cells have their own specialists too. Root hair cells have tiny hairs that massively increase surface area for absorbing water and nutrients. Xylem cells transport water upwards using thick walls reinforced with lignin, whilst phloem carries sugars both up and down the plant.
When studying cells, electron microscopes give much better magnification and resolution than light microscopes. This means you can see much finer details - essential for understanding how cells actually work.
Key Point: Each specialised cell has specific features that perfectly match its function - form always follows function in biology!
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Cell Division and Transport
Bacteria reproduce through binary fission - basically splitting in two. The number of bacteria grows exponentially following the pattern 2ⁿ, which is why bacterial infections can spread so quickly.
Mitosis is how your body grows and repairs itself. The DNA replicates, chromosomes get pulled apart, and one cell becomes two identical cells. This process is crucial for growth, repair, and asexual reproduction.
Stem cells are like biological Swiss Army knives - they're undifferentiated and can become any type of cell. Embryonic stem cells are the most versatile, whilst adult stem cells from bone marrow are more limited but still incredibly useful for medical treatments.
Understanding how substances move in and out of cells is essential. Diffusion moves particles from high to low concentration - think of how oxygen gets into your blood. Osmosis is specifically water moving through membranes, whilst active transport uses energy to move substances against the concentration gradient.
Key Point: The surface area to volume ratio is crucial for diffusion efficiency - smaller cells are generally better at exchanging materials with their environment.
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Where can I download the Knowunity app?
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4.9/5
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4.8/5
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