Unit 1 Biology

In the first unit this year in Biology, we are learning about cells.  Why they are the shape they are, what they have inside them and the differences between eukaryotic and prokaryotic cells.

One of the fundamental ideas is why cells are the small shape that we see most often.  We have determined that one important reason for the ‘smallness’ of cells is to enable material to move inside/outside of the cell in a timely manner.  This concept is called the surface area to volume ratio (SA:V ratio).

To fully appreciate how quickly diffusion and other processes can occur within a cell, we undertook a practical which compared different surface areas and volumes.  From this practical, we determined that the larger the surface area with a corresponding smaller volume is what will provide the most advantageous situation.

We used gel that had phenolphthalein added which made the gel pink.  We cut the gel into three different sized cubes and placed these in acid.  The acid turned the gel clear.  Some images are below.

Our results showed that the smallest cube, which had the largest surface area to volume ratio, enabled the acid to move into the gel the most.

This supported theory and clearly demonstrated how important SA:V ratio is to diffusion of material.

Hamish S and Mikael R
Year 11 Students