Biology
Chemistry
AP Chemistry
English
AP English Literature
Biology
Dec 10, 2025
86
4 pages
Sophie @soph.g.l
Cells are the building blocks of all living organisms and the foundation of biology. This topic covers what... Show more
Cells are the smallest structural and functional units of organisms. They're typically microscopic, containing cytoplasm and genetic material enclosed in a membrane. According to cell theory, all organisms are composed of cells, cells are the smallest living units, and new cells come from pre-existing cells.
Living organisms perform eight essential functions nutrition, metabolism, growth/development, sensitivity, excretion, homeostasis, movement, and reproduction. These functions occur at the cellular level and define what it means to be alive.
When working with cells, scientists use standard units of measurement with specific prefixes. These range from very large to extremely small measurements, allowing precise description of cellular structures and processes.
💡 The surface area to volume ratio is crucial for cell survival! As cells grow larger, this ratio decreases, making it harder for materials to move in and out efficiently—this is why most cells stay microscopic.
There are two major cell types that make up all living organisms prokaryotes and eukaryotes. Prokaryotic cells are smaller and simpler, lacking a distinct nucleus. Their DNA exists as a loop within the cytoplasm. Bacteria are common examples of prokaryotes and are considered some of Earth's oldest life forms.
Eukaryotic cells are more complex with a distinct nucleus that houses their DNA. Unlike prokaryotes, eukaryotic DNA is wrapped around proteins. These cells contain specialized membrane-bound organelles like mitochondria that perform specific functions. This division of labor increases cellular efficiency. Plants, animals, fungi, and protists all have eukaryotic cells.
The key differences between these cell types include size (eukaryotes are larger), ribosome size (eukaryotes have "eighties" while prokaryotes have "seventies"), and the presence of membrane-bound organelles in eukaryotes. These distinctions reflect different evolutionary paths and survival strategies.
🔬 Think of prokaryotic cells as studio apartments (everything in one space) and eukaryotic cells as houses with many rooms (specialized compartments for different functions)!
Scientists use different microscopes to study cells. Compound light microscopes use a series of lenses to magnify objects up to 1500x and have been used for centuries. Electron microscopes provide much higher resolution by using electron beams instead of light, though they can't view living specimens or show true colors.
There are two main types of electron microscopes Scanning Electron Microscopes (SEM) that create 3D surface images, and Transmission Electron Microscopes (TEM) where electrons pass through the specimen, with denser areas appearing darker. These can magnify thousands of times more than light microscopes.
When measuring cells, scientists use the formula "I AM" Image size = Actual size × Magnification. This can be rearranged to find any variable Magnification = Image size/Actual size or Actual size = Image size/Magnification. Remember to keep measurements in the same units!
🧮 When calculating cell measurements, always check your units! Using micrometers (μm) for one measurement and millimeters (mm) for another will give you wildly incorrect results.
Cell size is limited by physics and efficiency. Smaller cells have a larger surface area to volume ratio, making them better at transporting materials in and removing waste. This ratio is critical for cell survival and function.
As cells grow larger, they face multiple challenges. The diffusion distance becomes too long, and the surface-to-volume ratio decreases, preventing efficient exchange with the environment. Additionally, larger cells produce more heat and waste in proportion to their volume, potentially causing them to overheat.
To overcome these limitations, cells have developed adaptations. Some cells increase their surface area through protruding extensions or by flattening their shape. These modifications help maintain efficiency even when the cell needs to be larger for specialized functions.
🔍 Your body has over 200 different specialized cell types, each shaped perfectly for its function—from long nerve cells that transmit signals to flat skin cells that protect your body!
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
3
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the key processes of erosion and weathering in this comprehensive overview. Understand the mechanisms of corrosion, biological, chemical, and mechanical weathering, as well as mass movement types like slumping and rock falls. This summary is essential for Year 9 Geography students studying coastal and river processes.
BiologyExplore the dynamics of coastal erosion in Odisha, India, highlighting the impacts of climate change, human intervention, and natural processes. This summary covers the risks of flooding, the stability of coastal areas, and the opportunities for marine biodiversity and sustainable development. Ideal for students studying coastal systems and environmental geography.
Biologyfunctions of the digestive system
BiologyUnderstanding the composition and function of macromolecules in living organisms, including lipids, proteins, carbohydrates, and nucleic acids.
AP BiologyExplore the effectiveness of housing management strategies in Glasgow, focusing on the Gorbals Crown Street Regeneration and Dalmarnock Clyde Gateway Project. This summary covers urban change, renewal, planning, and the socio-economic impacts of these developments, highlighting improvements in community well-being, transport access, and environmental quality.
BiologyExplore the key features of glacial deposition, including terminal moraines, drumlins, and eskers. This summary covers the processes of glacier formation and movement, detailing how these unique landforms are created and their significance in geography. Ideal for higher geography students preparing for exams.
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Sophie
@soph.g.l
Cells are the building blocks of all living organisms and the foundation of biology. This topic covers what cells are, their types, and how they function as the basic units of life. Understanding cells helps explain how living things work... Show more
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Improve your grades
Join milions of students
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Cells are the smallest structural and functional units of organisms. They're typically microscopic, containing cytoplasm and genetic material enclosed in a membrane. According to cell theory, all organisms are composed of cells, cells are the smallest living units, and new cells come from pre-existing cells.
Living organisms perform eight essential functions: nutrition, metabolism, growth/development, sensitivity, excretion, homeostasis, movement, and reproduction. These functions occur at the cellular level and define what it means to be alive.
When working with cells, scientists use standard units of measurement with specific prefixes. These range from very large to extremely small measurements, allowing precise description of cellular structures and processes.
💡 The surface area to volume ratio is crucial for cell survival! As cells grow larger, this ratio decreases, making it harder for materials to move in and out efficiently—this is why most cells stay microscopic.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
There are two major cell types that make up all living organisms: prokaryotes and eukaryotes. Prokaryotic cells are smaller and simpler, lacking a distinct nucleus. Their DNA exists as a loop within the cytoplasm. Bacteria are common examples of prokaryotes and are considered some of Earth's oldest life forms.
Eukaryotic cells are more complex with a distinct nucleus that houses their DNA. Unlike prokaryotes, eukaryotic DNA is wrapped around proteins. These cells contain specialized membrane-bound organelles like mitochondria that perform specific functions. This division of labor increases cellular efficiency. Plants, animals, fungi, and protists all have eukaryotic cells.
The key differences between these cell types include size (eukaryotes are larger), ribosome size (eukaryotes have "eighties" while prokaryotes have "seventies"), and the presence of membrane-bound organelles in eukaryotes. These distinctions reflect different evolutionary paths and survival strategies.
🔬 Think of prokaryotic cells as studio apartments (everything in one space) and eukaryotic cells as houses with many rooms (specialized compartments for different functions)!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Scientists use different microscopes to study cells. Compound light microscopes use a series of lenses to magnify objects up to 1500x and have been used for centuries. Electron microscopes provide much higher resolution by using electron beams instead of light, though they can't view living specimens or show true colors.
There are two main types of electron microscopes: Scanning Electron Microscopes (SEM) that create 3D surface images, and Transmission Electron Microscopes (TEM) where electrons pass through the specimen, with denser areas appearing darker. These can magnify thousands of times more than light microscopes.
When measuring cells, scientists use the formula "I AM": Image size = Actual size × Magnification. This can be rearranged to find any variable: Magnification = Image size/Actual size or Actual size = Image size/Magnification. Remember to keep measurements in the same units!
🧮 When calculating cell measurements, always check your units! Using micrometers (μm) for one measurement and millimeters (mm) for another will give you wildly incorrect results.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Cell size is limited by physics and efficiency. Smaller cells have a larger surface area to volume ratio, making them better at transporting materials in and removing waste. This ratio is critical for cell survival and function.
As cells grow larger, they face multiple challenges. The diffusion distance becomes too long, and the surface-to-volume ratio decreases, preventing efficient exchange with the environment. Additionally, larger cells produce more heat and waste in proportion to their volume, potentially causing them to overheat.
To overcome these limitations, cells have developed adaptations. Some cells increase their surface area through protruding extensions or by flattening their shape. These modifications help maintain efficiency even when the cell needs to be larger for specialized functions.
🔍 Your body has over 200 different specialized cell types, each shaped perfectly for its function—from long nerve cells that transmit signals to flat skin cells that protect your body!
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
3
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the key processes of erosion and weathering in this comprehensive overview. Understand the mechanisms of corrosion, biological, chemical, and mechanical weathering, as well as mass movement types like slumping and rock falls. This summary is essential for Year 9 Geography students studying coastal and river processes.
BiologyExplore the dynamics of coastal erosion in Odisha, India, highlighting the impacts of climate change, human intervention, and natural processes. This summary covers the risks of flooding, the stability of coastal areas, and the opportunities for marine biodiversity and sustainable development. Ideal for students studying coastal systems and environmental geography.
Biologyfunctions of the digestive system
BiologyUnderstanding the composition and function of macromolecules in living organisms, including lipids, proteins, carbohydrates, and nucleic acids.
AP BiologyExplore the effectiveness of housing management strategies in Glasgow, focusing on the Gorbals Crown Street Regeneration and Dalmarnock Clyde Gateway Project. This summary covers urban change, renewal, planning, and the socio-economic impacts of these developments, highlighting improvements in community well-being, transport access, and environmental quality.
BiologyExplore the key features of glacial deposition, including terminal moraines, drumlins, and eskers. This summary covers the processes of glacier formation and movement, detailing how these unique landforms are created and their significance in geography. Ideal for higher geography students preparing for exams.
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Health
Algebra
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Algebra 1
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