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How Things Move in Cells: Diffusion, Osmosis, and Transport!

5

0

O

Olivia

14/08/2025

Biology

Osmosis, Active Transport and Diffusion

196

•

14 Aug 2025

•

5 pages

How Things Move in Cells: Diffusion, Osmosis, and Transport!

O

Olivia

@oliviag

Cell Transport Mechanisms: A comprehensive guide to diffusion, osmosis, and... Show more

osmosis, active transport and diffusion Simple Diffusion The net movement of particles from an area of high concentration to an area of low

Active Transport and Comparison with Passive Transport

Active transport is a crucial cellular process that moves particles against their concentration gradient, requiring energy in the form of ATP.

Definition: Active transport is the movement of particles from an area of low concentration to an area of high concentration, against a concentration gradient, requiring energy from ATP and carrier proteins.

The active transport energy requirement is essential for this process to occur, as it works against the natural tendency of particles to move from high to low concentration areas.

A comparison of transport rates for diffusion, facilitated diffusion, and active transport reveals:

  • Diffusion and facilitated diffusion rates increase with concentration until they reach a plateau.
  • Active transport rates also increase with concentration but level off when all carrier proteins are occupied.

Highlight: The rate of active transport is limited by the number of carrier proteins in the membrane, similar to how facilitated diffusion is limited by channel proteins.

osmosis, active transport and diffusion Simple Diffusion The net movement of particles from an area of high concentration to an area of low

Osmosis and Its Effects on Cells

Osmosis is a specific type of diffusion involving the movement of water molecules across a selectively permeable membrane.

Definition: Osmosis is the net movement of water molecules from an area of high water potential to an area of low water potential, down a water potential gradient, occurring passively without energy input.

Key concepts related to osmosis include:

  • Water potential: The concentration of water in a solution
  • Hypertonic solution: High solute concentration and low water potential
  • Hypotonic solution: Low solute concentration and high water potential
  • Isotonic solution: Equal water potential and solute concentration on both sides of the membrane

The osmosis effect on plant and animal cells varies depending on the tonicity of the surrounding solution:

  1. In a hypotonic solution:

    • Animal cells may undergo lysis (burst)
    • Plant cells become turgid but are protected from bursting by their cell wall

  2. In a hypertonic solution:

    • Animal cells become crenated (shriveled)
    • Plant cells undergo plasmolysis (cell membrane pulls away from cell wall)

  3. In an isotonic solution:

    • Animal cells remain normal
    • Plant cells become flaccid (water moves in and out at equal rates)

Vocabulary:

  • Plasmolysis: When a plant cell shrinks in a hypertonic solution
  • Crenation: The shriveling of an animal cell in a hypertonic solution
  • Lysis: The bursting of an animal cell in a hypotonic solution
  • Turgid: A plant cell's state when fully inflated with water in a hypotonic solution
osmosis, active transport and diffusion Simple Diffusion The net movement of particles from an area of high concentration to an area of low

Investigating Osmosis: Practical Application

To investigate osmosis, scientists often use experiments involving plant tissues, such as potato slices, in various concentrations of salt solutions.

The graph presented shows the percentage change in mass of potato tissue when placed in solutions of different concentrations:

  • The x-axis represents the salt solution concentration in mol/dm³
  • The y-axis shows the percentage change in mass of the potato tissue

Key observations from the graph:

  1. At lower salt concentrations (hypotonic solutions), the potato gains mass due to water uptake.
  2. At higher salt concentrations (hypertonic solutions), the potato loses mass as water leaves the cells.
  3. The isotonic point (Q) is where there is no change in mass, indicating equal water potentials inside and outside the potato cells.

Example: At the isotonic point (Q), there is no net movement of water because the water potential inside the potato and in the solution is the same.

Highlight: Understanding osmosis through such experiments is crucial for comprehending cellular processes and developing applications in fields like medicine and agriculture.

This investigation demonstrates the practical application of osmosis principles and provides a visual representation of how cells respond to different osmotic conditions.

osmosis, active transport and diffusion Simple Diffusion The net movement of particles from an area of high concentration to an area of low

Investigating Osmosis

This page presents experimental data on osmosis through graphical analysis.

Highlight: The isotonic point (Q) represents where there is no net movement of water, as water potentials are equal inside and outside the cell.

Example: The graph shows how different salt solution concentrations affect the percentage change in mass of tissue samples.

Definition: The isotonic point occurs when there is no change in mass due to equal water potentials between the solution and cell contents.

osmosis, active transport and diffusion Simple Diffusion The net movement of particles from an area of high concentration to an area of low

Simple Diffusion and Facilitated Diffusion

Simple diffusion and facilitated diffusion are passive transport processes that move particles from areas of high concentration to low concentration. While simple diffusion occurs directly through the cell membrane, facilitated diffusion utilizes channel proteins.

Definition: Simple diffusion is the net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient, requiring no energy.

Definition: Facilitated diffusion is the net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient, using channel proteins but still requiring no energy.

The facilitated diffusion factors affecting rate include:

  • Surface area
  • Temperature
  • Concentration gradient
  • Diffusion distance
  • Number of channel proteins

Highlight: The rate of facilitated diffusion is limited by the number of channel proteins available in the cell membrane.



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iOS user

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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.

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Sudenaz Ocak

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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.

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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.

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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

 

Biology

•

196

•

14 Aug 2025

•

5 pages

How Things Move in Cells: Diffusion, Osmosis, and Transport!

O

Olivia

@oliviag

Cell Transport Mechanisms: A comprehensive guide to diffusion, osmosis, and active transport processes in biological systems.

  • Facilitated diffusion factors affecting rate include surface area, temperature, concentration gradient, and the number of channel proteins
  • Osmosis effect on plant and animal cells... Show more

osmosis, active transport and diffusion Simple Diffusion The net movement of particles from an area of high concentration to an area of low

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Active Transport and Comparison with Passive Transport

Active transport is a crucial cellular process that moves particles against their concentration gradient, requiring energy in the form of ATP.

Definition: Active transport is the movement of particles from an area of low concentration to an area of high concentration, against a concentration gradient, requiring energy from ATP and carrier proteins.

The active transport energy requirement is essential for this process to occur, as it works against the natural tendency of particles to move from high to low concentration areas.

A comparison of transport rates for diffusion, facilitated diffusion, and active transport reveals:

  • Diffusion and facilitated diffusion rates increase with concentration until they reach a plateau.
  • Active transport rates also increase with concentration but level off when all carrier proteins are occupied.

Highlight: The rate of active transport is limited by the number of carrier proteins in the membrane, similar to how facilitated diffusion is limited by channel proteins.

osmosis, active transport and diffusion Simple Diffusion The net movement of particles from an area of high concentration to an area of low

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

Osmosis and Its Effects on Cells

Osmosis is a specific type of diffusion involving the movement of water molecules across a selectively permeable membrane.

Definition: Osmosis is the net movement of water molecules from an area of high water potential to an area of low water potential, down a water potential gradient, occurring passively without energy input.

Key concepts related to osmosis include:

  • Water potential: The concentration of water in a solution
  • Hypertonic solution: High solute concentration and low water potential
  • Hypotonic solution: Low solute concentration and high water potential
  • Isotonic solution: Equal water potential and solute concentration on both sides of the membrane

The osmosis effect on plant and animal cells varies depending on the tonicity of the surrounding solution:

  1. In a hypotonic solution:

    • Animal cells may undergo lysis (burst)
    • Plant cells become turgid but are protected from bursting by their cell wall

  2. In a hypertonic solution:

    • Animal cells become crenated (shriveled)
    • Plant cells undergo plasmolysis (cell membrane pulls away from cell wall)

  3. In an isotonic solution:

    • Animal cells remain normal
    • Plant cells become flaccid (water moves in and out at equal rates)

Vocabulary:

  • Plasmolysis: When a plant cell shrinks in a hypertonic solution
  • Crenation: The shriveling of an animal cell in a hypertonic solution
  • Lysis: The bursting of an animal cell in a hypotonic solution
  • Turgid: A plant cell's state when fully inflated with water in a hypotonic solution
osmosis, active transport and diffusion Simple Diffusion The net movement of particles from an area of high concentration to an area of low

Investigating Osmosis: Practical Application

To investigate osmosis, scientists often use experiments involving plant tissues, such as potato slices, in various concentrations of salt solutions.

The graph presented shows the percentage change in mass of potato tissue when placed in solutions of different concentrations:

  • The x-axis represents the salt solution concentration in mol/dm³
  • The y-axis shows the percentage change in mass of the potato tissue

Key observations from the graph:

  1. At lower salt concentrations (hypotonic solutions), the potato gains mass due to water uptake.
  2. At higher salt concentrations (hypertonic solutions), the potato loses mass as water leaves the cells.
  3. The isotonic point (Q) is where there is no change in mass, indicating equal water potentials inside and outside the potato cells.

Example: At the isotonic point (Q), there is no net movement of water because the water potential inside the potato and in the solution is the same.

Highlight: Understanding osmosis through such experiments is crucial for comprehending cellular processes and developing applications in fields like medicine and agriculture.

This investigation demonstrates the practical application of osmosis principles and provides a visual representation of how cells respond to different osmotic conditions.

osmosis, active transport and diffusion Simple Diffusion The net movement of particles from an area of high concentration to an area of low

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

Investigating Osmosis

This page presents experimental data on osmosis through graphical analysis.

Highlight: The isotonic point (Q) represents where there is no net movement of water, as water potentials are equal inside and outside the cell.

Example: The graph shows how different salt solution concentrations affect the percentage change in mass of tissue samples.

Definition: The isotonic point occurs when there is no change in mass due to equal water potentials between the solution and cell contents.

osmosis, active transport and diffusion Simple Diffusion The net movement of particles from an area of high concentration to an area of low

Simple Diffusion and Facilitated Diffusion

Simple diffusion and facilitated diffusion are passive transport processes that move particles from areas of high concentration to low concentration. While simple diffusion occurs directly through the cell membrane, facilitated diffusion utilizes channel proteins.

Definition: Simple diffusion is the net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient, requiring no energy.

Definition: Facilitated diffusion is the net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient, using channel proteins but still requiring no energy.

The facilitated diffusion factors affecting rate include:

  • Surface area
  • Temperature
  • Concentration gradient
  • Diffusion distance
  • Number of channel proteins

Highlight: The rate of facilitated diffusion is limited by the number of channel proteins available in the cell membrane.

We thought you’d never ask...

What is the Knowunity AI companion?

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.

Where can I download the Knowunity app?

You can download the app from Google Play Store and 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.

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

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