Concentration Gradients and Diffusion - Video Tutorials & Practice Problems
Get help from an AI Tutor
Ask a question to get started.
On a tight schedule?
Get a 10 bullets summary of the topic
1
concept
Concentration Gradients and Diffusion
Video duration:
4m
Play a video:
Video transcript
In this video, we're going to begin our lesson on concentration gradients and diffusion. And so a concentration gradient is really just defined as a difference in the concentration of a substance between 2 different areas. And so if we're comparing 2 different areas and one area has a higher or lower concentration than a different area, then a concentration gradient exists, because there's a difference in the concentration between those two areas. However, if we're comparing is really is really just a difference in the concentration of a substance between two areas. Now a molecule will be moving with or down its concentration gradient when that molecule is going from an area of high concentration down to an area of low concentration. And a molecule on the other hand will be moving against or up its concentration gradient when that molecule is going from an area of low concentration to an area of high concentration. So let's take a look at this image down below to clear up that idea. So notice that this image is all about concentration gradients, and it's broken up into 2 halves. We got the left hand side over here, we got the right hand side over here. So let's focus on the left hand side first and notice that we have a high concentration of this pink molecule over here on the left hand side, whereas over here on the right hand side we have quite a low concentration of, these pink molecules. And so if one of these pink molecules is going to move from an area of high concentration towards an area of low concentration, and the molecule movement is represented by the biker here, then this means that the molecule will be moving down or with its concentration gradient, moving from the area of high concentration down to the area of low concentration. And so just like it doesn't really take a lot of energy for a biker to basically cruise down a hill, it also does not take any energy for a molecule to move down or with its concentration gradient. So here we can indicate that absolutely no energy is required for molecules to move down or with their concentration gradient from areas of high concentration towards areas of low concentration. Now over here on the right hand side, notice that we have an image that has an area of low concentration of pink molecules over here on the left hand side and an area of much, much, much higher concentration of the pink molecule over here on the right hand side. And so if a molecule is trying to move from an area of low concentration towards an area of high concentration and the movement of the molecules represented by this biker that is going uphill, this means that the molecule would be moving, up or against its concentration gradient. And so, it will be moving up or against its energy for energy for a biker to bike up a hill, it takes energy for a molecule to move up or against its concentration gradient from an area of low concentration to an area of high concentration. So notice here we're saying that energy is required. And once again, this is an idea that we'll get to talk even more about as we move forward in our course. But for now, this here concludes our introduction to the concentration gradient and also molecules moving with or down the concentration gradient and or against or up the concentration gradient. And so we'll be able to get some practice applying these concepts as we move forward in our course. And in our next lesson video, we'll get to talk more about diffusion. So I'll see you guys in our next video.
2
concept
Diffusion
Video duration:
2m
Play a video:
Video transcript
In this video, we're going to talk about diffusion. And so diffusion is the net movement of a substance from an area of high concentration down to an area of low concentration. And so molecules have a natural tendency to diffuse with or down their concentration gradients from an area of high concentration to an area of low concentration. And so let's take a look at this example image down below at the diffusion of dye and water. And so notice that in this image, the blue circles represent water molecules, whereas the red circles represent dye molecules. And so over here on the far far left, notice that this person is adding a drop of dye to this beaker of water. And initially, when the person first adds the drop of dye, there's quite a high dye concentration in this one initial area. But in other areas of the beaker like here and over here and right here, you can see that there's quite a low dye concentration. There's really no dye at all. And so what starts to happen is diffusion is going to start to occur and so the dye is going to start to diffuse to areas of low concentration, as we see here, from area of high concentration down to an area of low concentration. And so that's what's starting to happen over here in this beaker. It's starting to diffuse and it's going to continue to diffuse from areas of high to areas of low concentration until equilibrium has been reached. And equilibrium is just when the entire beaker has equal concentrations of the die, and so the die is evenly distributed throughout the beaker. And so this is the idea of diffusion. And so this concludes our introduction to diffusion and we'll be able to get some practice applying these concepts as as we move forward throughout our course. So I'll see you all in our next video.
3
Problem
Problem
Which of the following statements about diffusion is true?
A
It's a process where water moves across a semi-permeable membrane to a region of high solute concentration.
B
It requires an expenditure of energy by the cell.
C
It's a process where molecules move from a region of lower concentration to a region of higher concentration.
D
It's a process where molecules move from a region of higher concentration to a region of lower concentration.
Do you want more practice?
We have more practice problems on Concentration Gradients and Diffusion