Diffusion Lab

What determines the efficiency of diffusion throughout the model ‘cells’?

Hypothesis: The smaller the surface area and volume, the higher the rate of diffusion will occur.

1cm cube of Agar

2cm cube of Agar

3cm cube of Agar

Agar cubes after being in the base solution for 10 mins

Cut up cube of Agar

1. In terms of maximizing diffusion, what was the most effective size cube that you tested?
The most effective cube that we tested was the smallest cube that was 1cm cube of agar.
2. Why was that size most effective at maximizing diffusion? What are the important factors that affect how materials diffuse into cells or tissues?
Size was most effective at maximizing diffusion as its surface area is larger than its volume, which can be seen through the surface area to volume ratio, 6:1. The smaller surface area and volume, the easier it is for diffusion to occur. Some factors that affect diffusion are temperature, surface area, volume and the size/shape of the molecule itself.
3. If a large surface area is helpful to cells, why do cells not grow to be very large?
A large surface area is helpful to cells because it allows for more materials to enter the cells. A smaller surface area is also helpful as it allows for diffusion to occur at a faster rate, and move towards the center of the cell faster. When a cell grows its volume increases at a greater rate than its surface area, causing diffusion to happen at a slower rate; decreasing growth.
4.  You have three cubes; A, B, and C. They have surface to volume ratios of 3:1, 5:2, and 4:1 respectively. Which of these cubes is going to be the most effective at maximizing diffusion? How do you know this?
The most effective at maximizing diffusion would be Cube C as the surface areas to volume ratio (4:1) contains a surface area that is proportionately larger than the volume. There is more surface area to be diffused but, the smaller volume allows for diffusion to travel and reach the center of the cell quicker.
5. How does your body adapt surface area-to-volume ratios to help exchange gases?
Our lungs contains sacs known as Alveoli, they have a large surface area to volume ratio due to their folded shape, causing diffusion to happen more quickly. Each sac contains a thin wall which increases their surface area and makes it easier for them to deal with any inflation that may occur in the lungs. This also decrease the amount of volume that diffusion needs for it to occur.
6. Why can’t certain cells, like bacteria, get to be the size of a small fish?
Certain cells cannot get to the size of a small fish because it would not be practical for them. It would make it harder for cells to diffuse materials well. The cells are small to begin with as it allows for diffusion to occur at a much greater rate. Increasing the size of the cells would only slow down the rate of diffusion.
7. What are the advantages of large organisms being multicellular?

Some advantages of large organisms being multicellular is that they grow. Single celled organisms can only reproduce and make more copies of themselves as they are not capable of growing, another is that due to them being multicellular, they can have multiple functions making them more efficient.