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K
Kesh Williams
30/11/2025
Biology
AQA Science trilogy higher tier B1
62
•
30 Nov 2025
•
AQA Science Trilogy Higher Tier: Biology 1
K
Kesh Williams
@keshwilliams_anpl
1 / 3
Cell Structure & Microscopy
Light microscopes can magnify objects up to 2000 times, whilst electron microscopes are much more powerful at 2 million times magnification. This massive difference explains why scientists can see incredible detail in cell structures that would be impossible with school microscopes.
Plant cells contain everything animal cells have, plus some extras: cell walls for structure, chloroplasts for photosynthesis, and permanent vacuoles filled with sap. Think of these as the plant's special toolkit for surviving without being able to move around.
Animal cells differentiate to become specialised for specific jobs. Nerve cells develop long axons and dendrites to carry electrical signals around your body, packed with mitochondria to power this demanding work.
Quick Tip: Remember that specialised cells gain extra structures to match their function - form follows function!
Specialised Plant Cells & Transport
Xylem cells are like the plant's water pipes, carrying water and minerals from roots to leaves. These cells actually die and become hollow tubes strengthened with lignin, creating an efficient transport system that also supports the plant's structure.
Phloem cells do the opposite job - they transport food made during photosynthesis to wherever it's needed. They form sieve plates between cells, allowing dissolved sugars to flow freely up and down the plant.
Diffusion happens when particles naturally spread from areas of high concentration to low concentration. The rate depends on temperature, concentration differences, and surface area - which is why your lungs have such a massive surface area for gas exchange.
Osmosis is specifically water movement through partially permeable membranes. Solutions can be isotonic (same concentration), hypertonic (higher concentration), or hypotonic (lower concentration) compared to inside the cell.
Remember: Diffusion is any particle movement, osmosis is only water movement through membranes!
Advanced Transport Mechanisms
When plant cells fill with water through osmosis, they create turgor pressure - this keeps plants rigid and upright. However, if plants lose too much water, plasmolysis occurs where the cell membrane pulls away from the cell wall, causing wilting.
Active transport is completely different from diffusion because it moves substances against the concentration gradient using energy from respiration. This is crucial for plant root hairs absorbing minerals from soil and for your gut absorbing nutrients into your bloodstream.
Exchange surfaces in complex organisms are specially adapted with large surface areas, thin walls for short diffusion distances, and efficient blood supplies. Single-celled organisms don't need these fancy systems because their entire surface area is already perfectly adequate for their small volume.
Understanding these transport mechanisms helps explain everything from why you need to water plants regularly to how your body absorbs nutrients efficiently.
Exam Tip: Active transport always requires energy and works against concentration gradients - the opposite of diffusion!
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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
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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
AQA Science Trilogy Higher Tier: Biology 1
K
Kesh Williams
@keshwilliams_anpl
Ever wondered how microscopes help us see tiny cells or why plants don't collapse when they lose water? This topic covers the fascinating world of cell structure and how substances move in and out of cells - knowledge that's absolutely... Show more
Cell Structure & Microscopy
Light microscopes can magnify objects up to 2000 times, whilst electron microscopes are much more powerful at 2 million times magnification. This massive difference explains why scientists can see incredible detail in cell structures that would be impossible with school microscopes.
Plant cells contain everything animal cells have, plus some extras: cell walls for structure, chloroplasts for photosynthesis, and permanent vacuoles filled with sap. Think of these as the plant's special toolkit for surviving without being able to move around.
Animal cells differentiate to become specialised for specific jobs. Nerve cells develop long axons and dendrites to carry electrical signals around your body, packed with mitochondria to power this demanding work.
Quick Tip: Remember that specialised cells gain extra structures to match their function - form follows function!
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Specialised Plant Cells & Transport
Xylem cells are like the plant's water pipes, carrying water and minerals from roots to leaves. These cells actually die and become hollow tubes strengthened with lignin, creating an efficient transport system that also supports the plant's structure.
Phloem cells do the opposite job - they transport food made during photosynthesis to wherever it's needed. They form sieve plates between cells, allowing dissolved sugars to flow freely up and down the plant.
Diffusion happens when particles naturally spread from areas of high concentration to low concentration. The rate depends on temperature, concentration differences, and surface area - which is why your lungs have such a massive surface area for gas exchange.
Osmosis is specifically water movement through partially permeable membranes. Solutions can be isotonic (same concentration), hypertonic (higher concentration), or hypotonic (lower concentration) compared to inside the cell.
Remember: Diffusion is any particle movement, osmosis is only water movement through membranes!
Sign up to see the contentIt's free!
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Improve your grades
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By signing up you accept Terms of Service and Privacy Policy
Advanced Transport Mechanisms
When plant cells fill with water through osmosis, they create turgor pressure - this keeps plants rigid and upright. However, if plants lose too much water, plasmolysis occurs where the cell membrane pulls away from the cell wall, causing wilting.
Active transport is completely different from diffusion because it moves substances against the concentration gradient using energy from respiration. This is crucial for plant root hairs absorbing minerals from soil and for your gut absorbing nutrients into your bloodstream.
Exchange surfaces in complex organisms are specially adapted with large surface areas, thin walls for short diffusion distances, and efficient blood supplies. Single-celled organisms don't need these fancy systems because their entire surface area is already perfectly adequate for their small volume.
Understanding these transport mechanisms helps explain everything from why you need to water plants regularly to how your body absorbs nutrients efficiently.
Exam Tip: Active transport always requires energy and works against concentration gradients - the opposite of diffusion!
We thought you’d never ask...
What is the Knowunity AI companion?
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Where can I download the Knowunity app?
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Is Knowunity really free of charge?
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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