Ever wondered what makes up every living thing around you?...
Biology752 views·Updated 29 Aug 2026·6 pagesGCSE AQA Biology Study Notes: Cells, Tissues, Organs
Nila Heartin@nilaheartin_tmsl
1 / 6
1
of 6
Animal and Plant Cells
Your body contains trillions of cells, each one a microscopic factory working 24/7 to keep you alive. Both animal and plant cells are eukaryotes, which simply means they have their genetic material safely stored in a nucleus rather than floating around freely.
Every cell has essential parts called organelles - think of them as tiny organs with specific jobs. The nucleus acts like the cell's brain, controlling everything and storing DNA. The cytoplasm is where most chemical reactions happen, whilst mitochondria are the powerhouses that release energy through respiration.
Plant cells have some extra features that animal cells don't need. The cell wall provides strength and structure, chloroplasts contain the green pigment chlorophyll for photosynthesis, and a large vacuole filled with cell sap helps maintain the plant's shape.
Key Point: Remember that structure always matches function - each organelle is perfectly designed for its specific job in the cell.
2
of 6
Prokaryotes and Bacteria
Unlike the complex cells in your body, prokaryotes are much simpler organisms that don't have a proper nucleus. Instead, their DNA just floats around freely in the cell, though it's still clumped together in one area.
Most prokaryotes are bacteria, and they're absolutely everywhere - in your gut helping with digestion, in yoghurt, even in extreme environments like hot springs. Don't let their simplicity fool you though; bacteria are incredibly successful and have survived for billions of years.
Bacterial cells have some unique features you won't find in human cells. The flagellum works like a tiny propeller for movement, whilst pili help bacteria stick to surfaces. Plasmids are small loops of extra DNA that bacteria can share with each other.
Key Point: Size matters in biology - bacteria are bigger than viruses but much smaller than the cells in your body.
3
of 6
Using Microscopes
Before microscopes were invented in the 17th century, nobody knew cells existed because they're far too small to see with your naked eye. Now you can explore this hidden world yourself with some simple techniques.
To observe onion cells, slice the onion extremely thinly so light can pass through, then add a drop of iodine to make the cells more visible. For cheek cells, gently swab the inside of your mouth and add methylene blue dye to highlight the structures.
Magnification tells you how many times bigger the image appears compared to the real object. To calculate total magnification, multiply the eyepiece lens power by the objective lens power. Working backwards from magnification lets you figure out the actual size of what you're observing.
Key Point: Always start with the lowest magnification and work your way up - it's much easier to find your specimen this way.
4
of 6
Light vs Electron Microscopes
Light microscopes are the workhorses of school biology labs, and for good reason. They're affordable, portable, and easy to use, plus you can observe living specimens in full colour. Perfect for getting started with cell biology.
Electron microscopes are the high-tech giants that reveal incredible detail and can magnify objects hundreds of thousands of times. They can even create 3D images, but they're expensive, huge, and require specimens to be dead and in a vacuum.
Understanding standard form becomes crucial when dealing with microscopic measurements. Numbers like 15,000,000 become much easier to handle as 1.5 × 10⁷. Remember: positive powers make numbers bigger, negative powers make them smaller.
Key Point: Choose your microscope based on what you need - light for live observations, electron for maximum detail and magnification.
5
of 6
Specialised Cells
Your body contains millions of different cells, each one perfectly adapted for its specific job. Sperm cells have long tails for swimming and lots of mitochondria for energy, whilst nerve cells are incredibly long to transmit messages across your body quickly.
Root hair cells in plants increase surface area to absorb more water from soil. Muscle cells contain special protein fibres that contract to create movement. Each cell's structure directly relates to its function.
The process of differentiation is how unspecialised stem cells become these specialist cells. In early embryos, stem cells can become any type of cell in the body. Most animal cells lose this flexibility as they mature, but plant cells often keep it throughout their lives.
Key Point: Stem cells are like biological blank slates - they have the potential to become any specialised cell type the body needs.
6
of 6
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Biology752 views·Updated 29 Aug 2026·6 pagesGCSE AQA Biology Study Notes: Cells, Tissues, Organs
Nila Heartin@nilaheartin_tmsl
Ever wondered what makes up every living thing around you? From the tiniest bacteria to massive trees, everything is built from cells - the building blocks of life. Understanding how these microscopic structures work and organise themselves is key to...
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of 6
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Animal and Plant Cells
Your body contains trillions of cells, each one a microscopic factory working 24/7 to keep you alive. Both animal and plant cells are eukaryotes, which simply means they have their genetic material safely stored in a nucleus rather than floating around freely.
Every cell has essential parts called organelles - think of them as tiny organs with specific jobs. The nucleus acts like the cell's brain, controlling everything and storing DNA. The cytoplasm is where most chemical reactions happen, whilst mitochondria are the powerhouses that release energy through respiration.
Plant cells have some extra features that animal cells don't need. The cell wall provides strength and structure, chloroplasts contain the green pigment chlorophyll for photosynthesis, and a large vacuole filled with cell sap helps maintain the plant's shape.
Key Point: Remember that structure always matches function - each organelle is perfectly designed for its specific job in the cell.
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Prokaryotes and Bacteria
Unlike the complex cells in your body, prokaryotes are much simpler organisms that don't have a proper nucleus. Instead, their DNA just floats around freely in the cell, though it's still clumped together in one area.
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Bacterial cells have some unique features you won't find in human cells. The flagellum works like a tiny propeller for movement, whilst pili help bacteria stick to surfaces. Plasmids are small loops of extra DNA that bacteria can share with each other.
Key Point: Size matters in biology - bacteria are bigger than viruses but much smaller than the cells in your body.
3
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Using Microscopes
Before microscopes were invented in the 17th century, nobody knew cells existed because they're far too small to see with your naked eye. Now you can explore this hidden world yourself with some simple techniques.
To observe onion cells, slice the onion extremely thinly so light can pass through, then add a drop of iodine to make the cells more visible. For cheek cells, gently swab the inside of your mouth and add methylene blue dye to highlight the structures.
Magnification tells you how many times bigger the image appears compared to the real object. To calculate total magnification, multiply the eyepiece lens power by the objective lens power. Working backwards from magnification lets you figure out the actual size of what you're observing.
Key Point: Always start with the lowest magnification and work your way up - it's much easier to find your specimen this way.
4
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- Improve your grades
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By signing up you accept Terms of Service and Privacy Policy
Light vs Electron Microscopes
Light microscopes are the workhorses of school biology labs, and for good reason. They're affordable, portable, and easy to use, plus you can observe living specimens in full colour. Perfect for getting started with cell biology.
Electron microscopes are the high-tech giants that reveal incredible detail and can magnify objects hundreds of thousands of times. They can even create 3D images, but they're expensive, huge, and require specimens to be dead and in a vacuum.
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Key Point: Choose your microscope based on what you need - light for live observations, electron for maximum detail and magnification.
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Specialised Cells
Your body contains millions of different cells, each one perfectly adapted for its specific job. Sperm cells have long tails for swimming and lots of mitochondria for energy, whilst nerve cells are incredibly long to transmit messages across your body quickly.
Root hair cells in plants increase surface area to absorb more water from soil. Muscle cells contain special protein fibres that contract to create movement. Each cell's structure directly relates to its function.
The process of differentiation is how unspecialised stem cells become these specialist cells. In early embryos, stem cells can become any type of cell in the body. Most animal cells lose this flexibility as they mature, but plant cells often keep it throughout their lives.
Key Point: Stem cells are like biological blank slates - they have the potential to become any specialised cell type the body needs.
6
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By signing up you accept Terms of Service and Privacy Policy
We thought you’d never ask...
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.
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