*refer to this photo for proof/data for the following questions*

In terms of maximizing diffusion, what was the most effective size cube that you tested?

The 1cm cube was the most effective agar cube as it was the only one to come out of the Sodium Hydroxide completely pink. This means that the cube was 100% diffused.

(A photo of all the agar cubes cut in half to see the effect of the Sodium Hydroxide after a period of ten minutes)

Why was that size most effective at maximizing diffusion?  What are the important factors that affect how materials diffuse into cells or tissues?

This size was the most effective at maximizing diffusion as it had the highest surface area and lowest volume. Overall, ratio is the best because the greater the difference in ratio between surface area (cell membrane) and volume, the slower the diffusion occurs. Surface area and volume are very important factors that affect how materials diffuse into cells or tissues. Some other factors could include concentration, temperature, type of material/thickness, and/or pressure.

If a large surface area is helpful to cells, why do cells not grow to be very large?

Although a large surface area is helpful to cells, through this lab we could see that cells do not grow to be very large because if they increase surface area, they are increase volume which in turn will increase the SAVratio. This means that in reality, diffusion becomes harder and less effective if cells were to grow very large.

Cells need to be small because they rely on diffusion for getting substances into and out of their cells.

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?

4:1 (C) because it has the highest surface area to volume ratio (highest SAVratio) which makes it the most efficient at maximizing diffusion.

How does your body adapt surface area-to-volume ratios to help exchange gases?

 Your body can adapt it’s ratios in a number of ways such as: folding the surface of the object/ cell
membrane, being shaped differently to perform specific functions, or/and cells divide when they get to bid to restore/have a larger SAVratio. Producing a high SAVratio is very important as this allows us to have a good gas exchange rate; however, if our surface are drops, so does our rate of gas exchange.

Why can’t certain cells, like bacteria, get to be the size of a small fish?

Bacteria is unicellular and made up of one cells therefore space is limited while a small fish would be multicellular and composed of many cells. The bacteria needs efficient diffusion in order to sustain itself. If the bacteria grew larger, than its surface area to volume ratio would be reduced; making diffusion less efficient, ultimately causing death to the bacteria.

What are the advantages of large organisms being multicellular?

By being multicellular organisms, plants and animals have overcome the problems of small cell sizes. Each cell has a large SAVratio which is necessary as there are a lot of functions needed to be performed with their specialized systems and cells. These features include gas exchange organs (lungs) and circulatory system (blood) to speed up and aid the movement of materials into and out of the organism.