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Dec 31, 2025
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Cell Transport: Passive & Active Highlights
M
Maggie Kidd
@maggiekidd_zrwv
1 / 3
Cell Transport Mechanisms
Ever wonder how your cells get what they need? Your cell membranes are selective gatekeepers that control what goes in and out. While some molecules can pass through the membrane directly, ions and large polar molecules need special transport systems.
There are three main ways molecules can cross cell membranes. Passive transport (also called facilitated diffusion) requires no energy and uses transport proteins to help specific molecules follow their concentration gradient. Think of it as using a door that's already unlocked—no pushing required!
Active transport is different because it requires energy, usually in the form of ATP. This process moves substances against their concentration gradient (from low to high concentration) using specialized protein pumps. A good example is the calcium pump that moves calcium ions across muscle cell membranes, which is crucial for your nervous system to function properly.
Did you know? Your nervous system runs on electricity created by the movement of ions across cell membranes. Without proper ion transport, you couldn't think, move, or feel!
Transport Types and Osmosis
Your cells are constantly moving materials in and out. The three major transport mechanisms are: diffusion (molecules moving from high to low concentration without energy), passive transport (using proteins but no energy), and active transport (requiring both proteins and energy).
For larger materials, cells use endocytosis to bring things in and exocytosis to push things out, both using membrane vesicles. Think of endocytosis as the cell "eating" and exocytosis as the cell "spitting out."
Osmosis is simply water diffusion across membranes. Water always moves from areas of high water concentration to low. This creates three possible conditions for cells: hypertonic (cell shrinks as water leaves), hypotonic (cell swells as water enters), or isotonic (balanced water flow). Your cells function best in isotonic environments!
The cell theory established by scientists like Van Leeuwenhoek, Hooke, Schleiden, and Schwann tells us that all living things are made of cells, cells are the smallest units of life, new cells come from existing cells, and cells pass on hereditary material to offspring.
Quick Connection: When you get dehydrated, your cells experience a hypertonic environment, which is why proper hydration is so important for cell function!
Cell Types and Structure
All cells share three essential features: a plasma membrane (controlling what enters and exits), a DNA-containing region (nucleus or nucleoid), and cytoplasm .
Cells come in two main types. Eukaryotic cells (like yours!) have membrane-bound compartments and a nucleus that houses DNA. Prokaryotic cells are smaller, simpler, and lack a nucleus—their DNA floats freely in a region called the nucleoid.
Size matters in cells! Smaller cells have a higher surface-to-volume ratio, making them more efficient at moving materials across their membranes. This is why prokaryotes can survive with simple diffusion while larger eukaryotic cells need specialized transport systems.
Prokaryotes may be simple, but they're incredibly diverse. They typically have a cell wall for protection, a sticky capsule for adhesion, flagella for movement, and pili for locomotion and sometimes reproduction. Many prokaryotes form communities called biofilms—slimy layers of cells working together for survival.
Biology Insight: Archaeans are fascinating prokaryotes that thrive in extreme environments like hot springs, salt lakes, and deep-sea vents where most life forms can't survive!
We thought you’d never ask...
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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.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content in Biology
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Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.9/5
App Store
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
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
Cell Transport: Passive & Active Highlights
M
Maggie Kidd
@maggiekidd_zrwv
Get ready to explore how cells manage the flow of materials across their membranes and the fundamental differences between cell types. Understanding these concepts is key to seeing how cells function as the basic units of life—whether they're simple bacteria... Show more
Cell Transport Mechanisms
Ever wonder how your cells get what they need? Your cell membranes are selective gatekeepers that control what goes in and out. While some molecules can pass through the membrane directly, ions and large polar molecules need special transport systems.
There are three main ways molecules can cross cell membranes. Passive transport (also called facilitated diffusion) requires no energy and uses transport proteins to help specific molecules follow their concentration gradient. Think of it as using a door that's already unlocked—no pushing required!
Active transport is different because it requires energy, usually in the form of ATP. This process moves substances against their concentration gradient (from low to high concentration) using specialized protein pumps. A good example is the calcium pump that moves calcium ions across muscle cell membranes, which is crucial for your nervous system to function properly.
Did you know? Your nervous system runs on electricity created by the movement of ions across cell membranes. Without proper ion transport, you couldn't think, move, or feel!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Transport Types and Osmosis
Your cells are constantly moving materials in and out. The three major transport mechanisms are: diffusion (molecules moving from high to low concentration without energy), passive transport (using proteins but no energy), and active transport (requiring both proteins and energy).
For larger materials, cells use endocytosis to bring things in and exocytosis to push things out, both using membrane vesicles. Think of endocytosis as the cell "eating" and exocytosis as the cell "spitting out."
Osmosis is simply water diffusion across membranes. Water always moves from areas of high water concentration to low. This creates three possible conditions for cells: hypertonic (cell shrinks as water leaves), hypotonic (cell swells as water enters), or isotonic (balanced water flow). Your cells function best in isotonic environments!
The cell theory established by scientists like Van Leeuwenhoek, Hooke, Schleiden, and Schwann tells us that all living things are made of cells, cells are the smallest units of life, new cells come from existing cells, and cells pass on hereditary material to offspring.
Quick Connection: When you get dehydrated, your cells experience a hypertonic environment, which is why proper hydration is so important for cell function!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Cell Types and Structure
All cells share three essential features: a plasma membrane (controlling what enters and exits), a DNA-containing region (nucleus or nucleoid), and cytoplasm .
Cells come in two main types. Eukaryotic cells (like yours!) have membrane-bound compartments and a nucleus that houses DNA. Prokaryotic cells are smaller, simpler, and lack a nucleus—their DNA floats freely in a region called the nucleoid.
Size matters in cells! Smaller cells have a higher surface-to-volume ratio, making them more efficient at moving materials across their membranes. This is why prokaryotes can survive with simple diffusion while larger eukaryotic cells need specialized transport systems.
Prokaryotes may be simple, but they're incredibly diverse. They typically have a cell wall for protection, a sticky capsule for adhesion, flagella for movement, and pili for locomotion and sometimes reproduction. Many prokaryotes form communities called biofilms—slimy layers of cells working together for survival.
Biology Insight: Archaeans are fascinating prokaryotes that thrive in extreme environments like hot springs, salt lakes, and deep-sea vents where most life forms can't survive!
We thought you’d never ask...
What is the Knowunity AI companion?
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.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
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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4.8/5
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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
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