Diffusion in Agar Cubes

Purpose: To determine which cell size allows for better diffusion

Hypothesis: A lesser volume of the agar cube would decrease the time it takes for the NaOH to react with the phenolphthalein in the agar cube

Pictures:

Assembling the agar cubes with different volumes

Submerging the agar cubes in the NaOH solution

The experiment at 3 and a half minutes

The experiment in 7 minutes

The result of the agar cubes after being submerged in the NaOH solution for about 10 minutes

At this point, the agar cubes were split up in half

Conclusion Questions:

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

• The most effective size cube in terms of maximizing diffusion was the 1 cm³ agar cube

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

• The 1 cm³ size was the most effective at maximizing diffusion because of has the highest surface area to volume ratio. It also has the smallest volume, allowing for a large area of the cube to be diffused.
• The important factors that affect how materials diffuse into cells or tissues are concentration, type of material, temperature, polarity, and size of the cell

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

• Despite a large surface area being helpful to cells, they do not grow to be very large because this makes diffusion inefficient. As the surface area increases, the volume does as well, thus hindering it from achieving a complete diffusion throughout the whole cell

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 cube that is going to be the most effective at maximizing diffusion will be the cube that has a surface area to volume ratio of 4:1, which is cube C. This is because it has the highest surface area to volume ration among the other cubes, therefore allowing diffusion to take place throughout the entire cube.

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

• Our body adapts to help exchange gases by dividing the cells to increase the surface area to volume ratios

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

• Bacteria do not get to be the size of a small fish because this decreases the surface area to volume ratio, making diffusion inefficient. In order to keep this from happening, they divide to maintain a good surface area to volume ratio. Furthermore, bacteria are unicellular organisms which means that they are dependent on the organelles for survival

7. What are the advantages of large organisms being multicellular?

• The advantages of large organisms being multicellular is that they depend on specialized cells which perform different functions to help the organism survive. It also allows the organism to grow larger in size. The more specialized cells that exists within the organism, the more effective they are at their task which allows the organism to perform more complex functions