# Surface area and diffusion relationship

### THE SURFACE AREA TO VOLUME RATIO

Use cubes of agar to investigate how size impacts diffusion. . What relationships do you notice between surface area, volume, surface-area-to- volume ratio. You should have a working definition for the terms osmosis, diffusion and an understanding of how the process works. As we investigate. Assuming that the membrane is permeable to the specific ion that you are considering when you increase surface area you increase the rate of.

The larger blocks have a smaller proportion of surface area than the smaller blocks.

### What is the relationship between surface area, volume, and diffusion in cells? | Yahoo Answers

The smallest block has 1. The largest block only has 0. This means that the hydrochloric acid is able to diffuse to the centre of the smallest block much faster than the largest block.

• How does surface area to volume ratio affect the rate of diffusion?

The acid took 48 minutes to diffuse to the centre of the largest block but only 1 minute in the smallest block. A living cell would not survive if it had to wait 48 minutes for oxygen to diffuse through it so living cells need to be very small.

## Investigating the relationship between cell size and rate of diffusion

When the surface area to volume ratio goes down it takes longer for the hydrochloric acid to diffuse into the cube but if the ratio goes up then the hydrochloric acid diffuses more quickly into the block of gelatin. Some shapes have a larger surface area to volume ratio so the shape of the object can have an effect on the rate of diffusion. It is important that cells have a large surface area to volume ratio so that they can get enough nutrients into the cell.

They can increase their surface area by flattening and becoming longer or by having a rough surface with lots of folds of cell membrane known as villi. The cell membrane is made up of a lipid bi-layer with many proteins integrated into it. The concentration of oxygen in the cell is always lower than outside the cell which causes the oxygen to diffuse in.

Gases will always dissolve from an area of high to low pressure. The concentration of carbon dioxide outside the cell is lower than the concentration in the cell so the carbon dioxide will always dissolve out of the cell. Single celled organisms such as amoebas have a large surface area to volume ratio because they are so small. They are able to get all the oxygen and nutrients they need by diffusion through the cell membrane. Larger organisms such as mammals have a relatively small surface area compared to their volume so they need special systems such as the lungs in order to get enough oxygen.

Surface area to volume ratio is very important in lungs where a large amount of oxygen has to get into the lungs. The lungs have a very large surface area because they contain millions of sacs called alveoli which allow oxygen to diffuse into the bloodstream. By having millions of these alveoli the lungs are able to cram a very large surface area into a small space.

This surface area is sufficient for all the oxygen we need to diffuse through it and to let the carbon dioxide out. By increasing the surface area the rate of diffusion will go up. Precautions a All the gelatin used should be taken from the same block to ensure that all the blocks are made up of the same materials. Limitations To help make this experiment more accurate, I repeated it three times for each block size and then used the average of all the results to plot a graph with a line of best fit.

## What is the relationship between surface area, volume, and diffusion in cells?

For cubes smaller than this, surface area is greater relative to volume than it is in larger cubes where volume is greater relative to surface area.

Sometimes a graph that shows how the relationship between two variables changes is more instructive. For example, a graph of the ratio of surface area to volume,clearly illustrates that as the size of an object increases without changing shapethis ratio decreases.

Mathematically, that tells us that the denominator volume increases faster relative to the numerator surface area as object size increases.

Organisms exhibit a variety of modifications, both physiological and anatomical, to compensate for changes in the surface area to volume ratio associated with size differences.

One example of this is the higher metabolic rates found in smaller homeothermic animals.

Because of their large surface area relative to volume, small animals lose heat at much higher rates than large animals, and therefore must produce more heat to offset the effects of thermal conductance. Another example is the variety of internal transport systems that have developed in plants and animals for actively moving materials throughout the organism, thus enabling them to circumvent the limits imposed by passive diffusion.

Many organisms have developed structures that actually increase their surface area: Graph the surface areas x axis and volumes y axis of these spheres on a standard plot and a log-log plot.

What happens to the line?