Jube's Cell Size and Diffusion Argumentation

Olajube Aladewolu

Cell Size and Diffusion Augmentation

Cells that have a larger surface area to volume ratio are more efficient at diffusing essential nutrients. My partners and I tested this by cutting the bacteria into rectangular prisms. Some of them were small, and some of them were large. We then observed how long each of them took to soak up the vinegar they were placed in. Initially, the small rectangular prisms had the following dimensions:

length:	2 cm
width:	1.5 cm
height:	1.5 cm
volume:	4.5 cm3
surface area:	16.5 cm2

The large rectangular prisms had the following dimensions:

length:	4 cm
width:	1.5 cm
height:	2.5 cm
volume:	15 cm3
surface area:	39.5 cm2

After sitting in the vinegar for 27 minutes (the bacteria changed color from blue to yellow as the vinegar diffused into it) the following dimensions of the blue bacteria was observed (the vinegar has not diffused into this portion yet) :

	small	large
length:	1cm	3cm
width:	.5cm	1cm
height:	.5cm	.5cm
volume:	.25 cm3	1.5 cm3
surface area:	2.5 cm2	10 cm2

surface area to volume ratio in the small bacteria= 3.67

surface area to volume ratio in the large bacteria=  2.63

rate of diffusion= .019 cm/sec

In the small bacteria, 94.34% of the volume turned yellow, and 90% of the volume turned yellow in the larger bacteria.

Essentially, our data showed us that there is more efficient diffusion in the smaller bacteria because it had a larger surface area to volume ratio. The larger bacteria had a smaller surface area to volume ratio of 2.63 when compared to the smaller bacteria’s ratio of 3.67 which made it a little bit harder for the vinegar to get to its center. This evidence is important and relevant because it shows that the smaller bacteria  is an at advantage when trying to obtain nutrients from outside sources. Evidently, the smaller bacteria works more efficiently to obtain it’s vital nutrients than the larger bacteria as it allowed more of the vinegar to freely pass through. Hence, cells are so small because nutrients need to be able to freely pass through them. When cells have a smaller surface area to volume ratio, they’ll be able to get what they need in a more efficient manner because the nutrients won’t have to travel as much to get to its center. In comparison, the small blue bacteria that was left in the center of the yellow bacteria after twenty- seven minutes had smaller dimensions (1cm x .5cm x .5cm) when compared to the dimensions of the larger blue bacteria that was left in the center of the yellow bacteria (3cm x 1cm x .5cm). Hence, nutrients are able to diffuse more efficiently into cells with a larger surface area to volume ratio.

In comparison, many argue that the rate of diffusion is directly related to cell size. They feel that nutrients diffuse at a faster rate through small cells than they do through large cells. However, this is invalid as it is not the case because both the small and large rectangular prism shaped bacteria have the same rate of diffusion of .019 cm/sec. Hence, nutrients in a cell diffuse at the same rate, however their efficiency is based on how big or small their surface area to volume ratio is. In a cell, the membranes are specialized to allow materials in and out of it; therefore, there’s slowing down the rate of diffusion in the larger cells. In essence, both of the bacteria (agar) are made up of the same membranes so there are no differences in their rates of diffusion. Thus, it is unacceptable to state that the rate of diffusion is related to cell size.