Transport mechanisms are the vital processes cells use to move... Show more
Algebra
Calculus 1
Algebra 1
OverigeSign 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
1 / 5
Passive and Active Transport Overview
Ever wonder how your cells decide what gets in and what stays out? The cell membrane acts as a gatekeeper, using different transport methods depending on the situation.
Transport mechanisms fall into two main categories: passive transport (which requires no energy) and active transport (which needs energy, usually from ATP). These systems ensure your cells can maintain their internal environment.
The difference comes down to concentration gradients - passive transport moves substances from high to low concentration (going "downhill"), while active transport can move substances against their concentration gradient (going "uphill").
💡 Think of passive transport like rolling a ball downhill (easy, no energy needed) and active transport like pushing a ball uphill (requires effort and energy).
Diffusion Mechanisms
Diffusion is how molecules naturally spread out from areas of high concentration to low concentration. It's happening all around and inside you right now!
Simple diffusion occurs when small, nonpolar molecules like oxygen and carbon dioxide pass directly through the lipid bilayer of the membrane. No help needed - they just slip between the phospholipids on their own.
Facilitated diffusion is different because it uses transport proteins to help specific molecules cross the membrane. Think of these proteins as doorways for molecules that would otherwise be stopped by the membrane. Glucose and amino acids often use this method to enter cells.
Both types of diffusion require no energy input, making them efficient ways for cells to obtain necessary substances.
Active Transport Systems
When cells need to move substances against their concentration gradient, they turn to active transport. This process requires energy, usually from ATP.
Primary active transport directly uses ATP energy to power movement. The sodium-potassium pump is a classic example - it pushes sodium out of the cell and brings potassium in, both against their concentration gradients. This helps maintain cell volume and creates electrical gradients needed for nerve cell function.
Secondary active transport is more efficient - it uses energy already stored in concentration gradients (created by primary active transport). For instance, glucose absorption in your intestines happens when sodium moving down its concentration gradient pulls glucose along with it.
⚡ Active transport is like your cell's premium delivery service - it costs energy, but ensures important molecules get exactly where they need to go, even when conditions aren't favorable.
Bulk Transport Methods
Sometimes cells need to move large particles or lots of material at once. That's where bulk transport comes in!
Endocytosis is the cell's way of taking things in. The cell membrane folds inward, forming a pocket that eventually pinches off into a vesicle inside the cell. There are several types: phagocytosis (cell eating), pinocytosis (cell drinking), and receptor-mediated endocytosis (targeted uptake of specific substances).
Exocytosis works in reverse - vesicles inside the cell fuse with the cell membrane, releasing their contents to the outside. This is how your cells secrete hormones, neurotransmitters, and waste products.
Specialized channel proteins and carrier proteins in the membrane also help with transport. Channel proteins form pores for specific substances, while carrier proteins change shape to move molecules across the membrane.
Transport Regulation and Factors
Your cells constantly adjust their transport processes in response to changing conditions. Several factors influence how quickly substances move across membranes.
The concentration gradient is the driving force behind passive transport - the steeper the gradient, the faster diffusion occurs. For charged particles like ions, the electrochemical gradient combines both concentration and electrical forces to determine movement.
Temperature significantly affects transport rates - warmer temperatures make molecules move faster, speeding up both passive and active transport. That's one reason why extreme body temperatures can be dangerous.
Membrane permeability varies based on which transport proteins are present and active in different cell types. Your nerve cells, for example, have specialized ion channels that allow for rapid signaling.
🔍 Understanding transport mechanisms helps explain how medications work, how nutrients are absorbed, and even how certain diseases disrupt normal cellular function.
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.
Most popular content: Active Transport
Most popular content in AP Biology
Most popular content
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
2.9 Mechanisms of Transport in Biology
Transport mechanisms are the vital processes cells use to move substances across their membranes. These mechanisms maintain the proper balance of nutrients, waste, and other molecules needed for cellular function. Understanding how cells control what enters and exits is fundamental... Show more
Passive and Active Transport Overview
Ever wonder how your cells decide what gets in and what stays out? The cell membrane acts as a gatekeeper, using different transport methods depending on the situation.
Transport mechanisms fall into two main categories: passive transport (which requires no energy) and active transport (which needs energy, usually from ATP). These systems ensure your cells can maintain their internal environment.
The difference comes down to concentration gradients - passive transport moves substances from high to low concentration (going "downhill"), while active transport can move substances against their concentration gradient (going "uphill").
💡 Think of passive transport like rolling a ball downhill (easy, no energy needed) and active transport like pushing a ball uphill (requires effort and energy).
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
Diffusion Mechanisms
Diffusion is how molecules naturally spread out from areas of high concentration to low concentration. It's happening all around and inside you right now!
Simple diffusion occurs when small, nonpolar molecules like oxygen and carbon dioxide pass directly through the lipid bilayer of the membrane. No help needed - they just slip between the phospholipids on their own.
Facilitated diffusion is different because it uses transport proteins to help specific molecules cross the membrane. Think of these proteins as doorways for molecules that would otherwise be stopped by the membrane. Glucose and amino acids often use this method to enter cells.
Both types of diffusion require no energy input, making them efficient ways for cells to obtain necessary substances.
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
Active Transport Systems
When cells need to move substances against their concentration gradient, they turn to active transport. This process requires energy, usually from ATP.
Primary active transport directly uses ATP energy to power movement. The sodium-potassium pump is a classic example - it pushes sodium out of the cell and brings potassium in, both against their concentration gradients. This helps maintain cell volume and creates electrical gradients needed for nerve cell function.
Secondary active transport is more efficient - it uses energy already stored in concentration gradients (created by primary active transport). For instance, glucose absorption in your intestines happens when sodium moving down its concentration gradient pulls glucose along with it.
⚡ Active transport is like your cell's premium delivery service - it costs energy, but ensures important molecules get exactly where they need to go, even when conditions aren't favorable.
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
Bulk Transport Methods
Sometimes cells need to move large particles or lots of material at once. That's where bulk transport comes in!
Endocytosis is the cell's way of taking things in. The cell membrane folds inward, forming a pocket that eventually pinches off into a vesicle inside the cell. There are several types: phagocytosis (cell eating), pinocytosis (cell drinking), and receptor-mediated endocytosis (targeted uptake of specific substances).
Exocytosis works in reverse - vesicles inside the cell fuse with the cell membrane, releasing their contents to the outside. This is how your cells secrete hormones, neurotransmitters, and waste products.
Specialized channel proteins and carrier proteins in the membrane also help with transport. Channel proteins form pores for specific substances, while carrier proteins change shape to move molecules across the membrane.
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 Regulation and Factors
Your cells constantly adjust their transport processes in response to changing conditions. Several factors influence how quickly substances move across membranes.
The concentration gradient is the driving force behind passive transport - the steeper the gradient, the faster diffusion occurs. For charged particles like ions, the electrochemical gradient combines both concentration and electrical forces to determine movement.
Temperature significantly affects transport rates - warmer temperatures make molecules move faster, speeding up both passive and active transport. That's one reason why extreme body temperatures can be dangerous.
Membrane permeability varies based on which transport proteins are present and active in different cell types. Your nerve cells, for example, have specialized ion channels that allow for rapid signaling.
🔍 Understanding transport mechanisms helps explain how medications work, how nutrients are absorbed, and even how certain diseases disrupt normal cellular function.
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.
3
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Mock Exam
Quiz
Flashcards
Essay
Similar Content
Anatomy and Physiology
Anatomy Unit 1: Directional Terms (superior, inferior, ventral, dorsal, etc.) and Organ Systems
AP BiologyKidney Function & Osmoregulation
Explore the intricate functions of the kidney, focusing on the nephron's role in ultrafiltration and osmoregulation. This summary covers key components such as the glomerulus, Bowman's capsule, and the countercurrent multiplier mechanism, highlighting how the kidney maintains homeostasis and regulates water balance in the body. Ideal for students studying biology and human physiology.
Biology14
Unit 2 AP Bio notes
All notes from AP Classroom slides and videos
AP Biology11th
Homeostasis Notes
Reviews homeostasis for AP Bio
AP BiologyMolecular Basis of Life, Aromic Structure, Bonds, Properties of Water…
Understanding the arrangement of electrons in atom shells and how chemical bonds form through valence electrons.
AP BiologyCollege
Plant Organization
Plant Organs
AP BiologyMost popular content: Active Transport
Most popular content in AP Biology
Most popular content
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