Aim and Background

This is an experiment to analyze how the Surface Area / Volume Ratio affects the rate of diffusion and how this relates to the size and form of life beings.

The surface country to volume ratio in life beings is really of import. Foods and O need to spread through the cell membrane and into the cells. Most cells are no longer than 1mm in diameter because little cells enable foods and O to spread into the cell rapidly and let waste to spread out of the cell rapidly. If the cells were any bigger than this so it would take excessively long for the foods and O to spread into the cell so the cell would likely non survive.

Single celled beings can last as they have a big adequate surface country to let all the O and foods they need to spread through. Larger multi-celled beings need variety meats to respire such as lungs or gills.

Method

The ground I chose to make this peculiar experiment is because I found it really interesting and besides because the purpose. method. results- fundamentally the whole experiment would be easy understood by the mean individual who knew nil about Surface Area/Volume Ratio. The variable being tested in this experiment is the rate of diffusion in relation to the size of the gelatin regular hexahedron. Another experiment 1 could make to find the surface country to volume ratio is to build a set of regular hexahedrons out of building paper- 1 ten 1. 2 ten 2. 3 ten 3 and 4 tens 4 ( centimeter ) . Then utilize this expression to find the surface area- L x W x 6 and compare it with the volumes. The expression to find volumes of regular hexahedron is L x W x H. Although that type of experiment will demo no penetration into SA/V ratio in relation to the rate of diffusion.

Equipment

1. Agar-phenolphthalein – Na hydrated oxide jelly

2. O. 1 M hydrochloric acid

3. Ruler ( centimeter and millimeter )

4. Razor blade

5. Paper towel

6. Beaker

Method

1. A block of gelatin which has been dyed with phenolphthalein should be cut into blocks of the undermentioned sizes ( millimeter ) .

5 ten 5 ten 5

10 ten 10 ten 10

15 ten 15 ten 15

20 ten 20 ten 20

30 ten 30 ten 30

20 ten 5 ten 5

Phenolphthalein is an acid/alkali index dye. In the alkali conditions of the gelatin it is ruddy or purple but when it gets exposed to acid it turns about colorless.

Gelatin is used for these trials because it is permeable which means it acts like a cell. It is easy to cut into the needed sizes and the hydrochloric acid can spread at an even rate through it.

2. A little beaker was filled with about 400ml of 0. 1 molar Hydrochloric acid. This is a sufficient sum of acid to guarantee that all the block sizes are to the full covered in acid when dropped into the beaker.

3. One of the blocks is dropped into this beaker. left for 10 proceedingss. so removed. dried. and cut in two to mensurate the deepness of incursion. This trial should be repeated for all the sizes of blocks three times to guarantee an accurate trial. Fresh acid should be used for each block to do certain that this does non impact the experiment’s consequences.

4. The Surface Area/Volume Ratio and an norm of the consequences can so be worked out. A graph of Surface Area to Volume Ratio can so be plotted along with per centums left coloured and uncoloured. From this graph we will be able to see how surface country affects the rate of diffusion of stuffs into the regular hexahedron.

Consequences

I carried out the above experiment and these consequences were obtained.

Dimensions ( millimeter ) Surface Area Volume ( V ) ( millimeter ) Surface Area / Volume Ratio Test 1 Test 2 Test 3

5 ten 5 ten 5 150 125 1. 2:1 1mm 1mm 1mm

10 ten 10 ten 10 600 1. 000 0. 6:1 1mm 1mm 1mm

20 ten 20 ten 20 2. 400 8. 000 0. 3:1 1mm 1mm 1mm

30 ten 30 ten 30 5. 400 27. 000 0. 2:1 1mm 1mm 1mm

The Surface Area to Volume Ratio is calculated by

SA = centimeter

From these consequences I was able to do a graph of the volume still coloured along with the per centums left colored and uncolored.

Dimensions ( millimeter ) Volume left colored 3 ( millimeter ) Percentage coloured compared to original volume Percentage penetratedby the acid

5 ten 5 ten 5 3mm 60 % 40 %

10 ten 10 ten 10 8mm 80 % 20 %

20 ten 20 ten 20 18mm 90 % 10 %

30 ten 30 ten 30 28mm 93. 3 % 6. 7 %

Length of side non penetrated = ( s – 2x )

3

Volume left colored ( Vc ) = ( s – 2x )

Percentage still coloured ( C % ) = Vc x 100

V 1

Percentage of regular hexahedron penetrated = 100 – C %

Interpretation

In all the blocks of gelatin the rate of incursion of the hydrochloric acid from each side would hold been the same but all the regular hexahedrons have different per centums still coloured because they are different sizes. As the blocks get bigger the hydrochloric acid to spread smaller per centums of the regular hexahedron. It would take longer to wholly spread the largest regular hexahedron even though the rate of diffusion is the same for all the regular hexahedrons.

As the volume of the blocks goes up the Surface Area/Volume ratio goes down. The larger blocks have a smaller surface country than the smaller blocks. The smallest block has 1. 2mm squared of surface country for every 1mm cubed of volume. The largest block merely has 0. 2mm squared of surface country for each 1mm cubed of volume. This means that the hydrochloric acid is able to spread the smallest block much faster than the largest block.

When the Surface Area/Volume Ratio goes down it takes longer for the hydrochloric acid to spread into the regular hexahedron but if the ratio goes up so the hydrochloric acid diffuses more rapidly into the block of gelatin. Some forms have a larger surface country to volume ratio so the form of the object can hold an consequence on the rate of diffusion.

The individual mistake or restriction I encountered was the impossiblity to exactly mensurate the size of gelatin block. I measured the sizes to the nearest millimeter so the sizes of block that I used should be right to the nearest millimeter.

Discussion

It is of import that cells have a big surface country to volume ratio so that they can acquire adequate foods into the cell.

Single celled beings have a big surface country to volume ratio because they are so little. They are able to acquire all the O and foods they need by diffusion through the cell membrane.

Here is a diagram of a standard foliage:

Their are gaps within a foliage called pore. These allow for the gases to flux in and out of the foliage. Leafs of workss have a big surface country. and the irregular-shaped. squashy cells increase the country even more intending a larger sum of gas exchange. An illustration of surface country to volume ratio in a existent universe context would be something such as the illustration that was merely explained.

Therefore. by increasing the surface country the rate of diffusion will travel up.

Appendixs

( 2002 ) Biology: The Surface Area to Volume Ratio of a Cell [ Web papers ] hypertext transfer protocol: //www. geocities. com/CapeCanaveral/Hall/1410/lab-B-24. hypertext markup language

This piece of information was a good start for the probe of Surface Area to Volume Ratio probe. Even though it has no reference about rate of diffusion in relation to SA/V ratios. its relevancy to my probe was important.

( 2002 ) Encyclopedia Britannica: Biology- Surface Area to Volume Ratio

[ CD-ROM ]

I found this beginning of information to be really dependable. The Encyclopedia Britannica is a popular and believable manner to derive information. It covers the whole scope of factors associating to SA/V ratios every bit good as the rate of diffusion. It was really appropriate for my probe.

( 2000 ) Sizes of Organism’s: Surface country to Volume ratio [ Web papers ] hypertext transfer protocol: //www. tiem. utk. edu/~mbeals/area_volume. hypertext markup language

This papers had an in depth treatment about the relation between Surface Area and Volume Ratio’s. It used plentifulness of illustrations to acquire the point across more clearly. It besides touched on Surface Area to Volume Ratio’s of sphere’s.