Subjects
Maths
Chemistry
Biology
English Language
History
Responding to change (a2 only)
Infection and response
Homeostasis and response
Energy transfers (a2 only)
Cell biology
Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
Organisation
Substance exchange
Bioenergetics
Genetic information & variation
Inheritance, variation and evolution
Genetics & ecosystems (a2 only)
Ecology
Cells
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
72
•
12 Dec 2025
•
Billie Bowen
@billiebowen_jqah
Atoms, cells, and microscopes might seem complicated, but they're actually... Show more
Ever wondered what makes gold different from carbon? It's all about elements – substances made up of atoms that have the same number of protons in their nucleus. Think of elements as the pure ingredients of everything in the universe.
The atomic number tells you exactly what element you're dealing with because it counts the protons. If you change the number of protons, you get a completely different element – it's like nature's ID card system.
Isotopes are basically twins with different weights. Carbon-12 and carbon-13 are both carbon (same number of protons), but carbon-13 has an extra neutron making it slightly heavier. Scientists use these to calculate relative atomic mass, which is just the average weight considering all the different isotopes.
Quick Tip: Remember that protons determine the element type – everything else can vary!
Atoms are incredibly tiny – about 0.1 nanometers across – but they're perfectly organised little worlds. Picture a football stadium where the nucleus (containing protons and neutrons) is like a marble in the centre, whilst electrons zoom around the edges.
The nucleus packs almost all the atom's weight into a space 10,000 times smaller than the whole atom. Protons are heavy and positive, neutrons are heavy but neutral, and electrons are tiny with a negative charge.
Here's the clever bit: atoms are normally neutral because they have equal numbers of protons and electrons. When atoms become ions (charged particles), they've either gained or lost electrons. Add electrons for negative ions, lose them for positive ones.
Memory Trick: Electrons are on the outside, so they're the ones that can escape or join – protons stay put in the nucleus!
Stem cells are like biological shape-shifters – they can transform into any type of cell your body needs. Imagine having a bunch of blank cells that could become brain cells, muscle cells, or even heart cells when needed.
Embryonic stem cells are the ultimate multitaskers because they can become absolutely any cell type. Adult stem cells are more limited – they're found in places like bone marrow and can only make certain types of cells.
The exciting bit is that stem cells could revolutionise medicine. Scientists think they could grow new nerve cells for paralysed people or insulin-producing cells for diabetics. Therapeutic cloning could even create stem cells that match a patient's genes perfectly.
Plants use stem cells too! Meristems in root and shoot tips contain plant stem cells that keep growing throughout the plant's life. Gardeners use this to create identical plant clones quickly and cheaply.
Did You Know: You're constantly using stem cells – they're replacing your skin cells, blood cells, and healing your injuries right now!
Your chromosomes are like instruction manuals coiled up inside every cell's nucleus. Humans have 23 pairs (46 total), and each chromosome contains thousands of genes that control everything from your hair colour to your height.
Mitosis is your body's photocopying system for making new cells. Before dividing, each cell copies its DNA completely – this creates those X-shaped chromosomes you see in textbooks where each arm is an identical copy.
During mitosis, chromosomes line up in the cell's centre, then get pulled apart to opposite ends. The cell then splits down the middle, creating two identical cells with exactly the same DNA as the original.
Your body uses mitosis constantly for growth and repair. Every time you get taller, heal a cut, or replace old cells, mitosis is working behind the scenes to keep you healthy.
Fun Fact: You make about 25 million new cells every second through mitosis – that's like replacing a small city's population!
Light microscopes let you peek into the cellular world, showing you big structures like nuclei. Electron microscopes are the superheroes of magnification – they reveal tiny details like ribosomes that light microscopes can't see.
The magnification formula (Image size ÷ Real size) helps you work out how much bigger something looks under the microscope. Just make sure both measurements use the same units!
Osmosis is water's natural tendency to move from where there's lots of it to where there's less of it, but only through partially permeable membranes. Think of it like water trying to balance things out by moving through a selective barrier.
Real-Life Example: When you put a raisin in water, it swells up because water moves into the raisin through osmosis, trying to dilute the concentrated sugars inside.
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
Billie Bowen
@billiebowen_jqah
Atoms, cells, and microscopes might seem complicated, but they're actually the building blocks that make up everything around you – including you! Understanding these basic concepts will help you ace your science tests and see how amazing the microscopic world... Show more
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Ever wondered what makes gold different from carbon? It's all about elements – substances made up of atoms that have the same number of protons in their nucleus. Think of elements as the pure ingredients of everything in the universe.
The atomic number tells you exactly what element you're dealing with because it counts the protons. If you change the number of protons, you get a completely different element – it's like nature's ID card system.
Isotopes are basically twins with different weights. Carbon-12 and carbon-13 are both carbon (same number of protons), but carbon-13 has an extra neutron making it slightly heavier. Scientists use these to calculate relative atomic mass, which is just the average weight considering all the different isotopes.
Quick Tip: Remember that protons determine the element type – everything else can vary!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Atoms are incredibly tiny – about 0.1 nanometers across – but they're perfectly organised little worlds. Picture a football stadium where the nucleus (containing protons and neutrons) is like a marble in the centre, whilst electrons zoom around the edges.
The nucleus packs almost all the atom's weight into a space 10,000 times smaller than the whole atom. Protons are heavy and positive, neutrons are heavy but neutral, and electrons are tiny with a negative charge.
Here's the clever bit: atoms are normally neutral because they have equal numbers of protons and electrons. When atoms become ions (charged particles), they've either gained or lost electrons. Add electrons for negative ions, lose them for positive ones.
Memory Trick: Electrons are on the outside, so they're the ones that can escape or join – protons stay put in the nucleus!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Stem cells are like biological shape-shifters – they can transform into any type of cell your body needs. Imagine having a bunch of blank cells that could become brain cells, muscle cells, or even heart cells when needed.
Embryonic stem cells are the ultimate multitaskers because they can become absolutely any cell type. Adult stem cells are more limited – they're found in places like bone marrow and can only make certain types of cells.
The exciting bit is that stem cells could revolutionise medicine. Scientists think they could grow new nerve cells for paralysed people or insulin-producing cells for diabetics. Therapeutic cloning could even create stem cells that match a patient's genes perfectly.
Plants use stem cells too! Meristems in root and shoot tips contain plant stem cells that keep growing throughout the plant's life. Gardeners use this to create identical plant clones quickly and cheaply.
Did You Know: You're constantly using stem cells – they're replacing your skin cells, blood cells, and healing your injuries right now!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Your chromosomes are like instruction manuals coiled up inside every cell's nucleus. Humans have 23 pairs (46 total), and each chromosome contains thousands of genes that control everything from your hair colour to your height.
Mitosis is your body's photocopying system for making new cells. Before dividing, each cell copies its DNA completely – this creates those X-shaped chromosomes you see in textbooks where each arm is an identical copy.
During mitosis, chromosomes line up in the cell's centre, then get pulled apart to opposite ends. The cell then splits down the middle, creating two identical cells with exactly the same DNA as the original.
Your body uses mitosis constantly for growth and repair. Every time you get taller, heal a cut, or replace old cells, mitosis is working behind the scenes to keep you healthy.
Fun Fact: You make about 25 million new cells every second through mitosis – that's like replacing a small city's population!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Light microscopes let you peek into the cellular world, showing you big structures like nuclei. Electron microscopes are the superheroes of magnification – they reveal tiny details like ribosomes that light microscopes can't see.
The magnification formula (Image size ÷ Real size) helps you work out how much bigger something looks under the microscope. Just make sure both measurements use the same units!
Osmosis is water's natural tendency to move from where there's lots of it to where there's less of it, but only through partially permeable membranes. Think of it like water trying to balance things out by moving through a selective barrier.
Real-Life Example: When you put a raisin in water, it swells up because water moves into the raisin through osmosis, trying to dilute the concentrated sugars inside.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Parts of a microscope
Biologycytoskeleton
BiologyBio notes
BiologyExplanation based on class notes and textbooks about living things in living environments
BiologyA list of Eukaryotic cell organelles and their basic functions
BiologyDescribing the Parts of Microscope with Functions
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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
Physics
Sociology