The surface-area-to-volume ratio defines what aspect of a cell? a. whether it is eukaryotic or p

The surface-area-to-volume ratio defines what aspect of a...

Key Concepts

Surface-Area-to-Volume Ratio

This concept measures the relationship between the surface area of a cell and its volume. It is critical because it influences how efficiently a cell can exchange materials, such as nutrients and waste products, with its environment through its membrane.

Cell Size

The surface-area-to-volume ratio directly impacts cell size, as it determines the efficiency of diffusion processes necessary for survival. In biology, as cells grow larger, their volume increases faster than their surface area, which can limit the cell's ability to meet metabolic demands.

Transcript

00:02 We are being asked to determine which aspect of the cell the surface area to volume ratio defines.

00:09 The ratio is essentially the fraction you form when you divide the surface area of an object by its volume.

00:16 So its surface area divided by volume.

00:19 Now let's look at a couple of examples.

00:21 Suppose that you have a one centimeter sided cube.

00:25 The surface area of the cube would be the areas of each one of its sides.

00:32 So basically one of the faces here times six because a cube has six sides.

00:38 So it would be six times one centimeter squared or six centimeters squared.

00:48 Now the volume of an object is width times length times height.

00:55 Those are all the same for a cube.

00:58 So for a cube, that would be one, centimeter cubed for our particular cube here or one centimeter cubed and the surface area to volume ratio would then be six divided by one or six for a cube whose sides are two centimeters each the surface area would be six times two centimeters squared right so two centimeter squares would be the area of one of the faces of the cube which is four so if you want to three, four, type six, that is 24 centimeters squared.

01:43 The volume of this cube would then be two centimeters cubed or eight centimeters cubed.

01:54 And the surface area to volume ratio for this two centimeter sided cubed would be 24 divided by eight, which is equal to three.

02:07 So, as you can see, the larger an object becomes, the smaller the surface area to volume ratio becomes.

02:14 Now why does this matter to cells? well, a cell takes in nutrients and disposes of waste through its plasma membrane.

02:23 So as a cell gets larger and the surface area to volume ratio gets smaller, there is less plasma membrane per unit volume of the cell.

02:33 Think about it this way...

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