Surface Area to Volume Worksheet 1. Surface area to volume ratio is important because, as cell ages and produces essential products such as proteins it increases in size. As it increases in size the speed of chemical reaction increases, since now the cell is big, it needs more reactants to produce essential products it needs. 2. The important point is that the surface area to the volume ratio gets smaller as the cell gets larger. Thus, if the cell grows beyond a certain limit, not enough material will be able to cross the membrane fast enough to accommodate the increased cellular volume. 3. Unicellular organisms are generally smaller than multi-cellular organisms. Their small size means a large SA:V ratio. This means it is easier for materials to move into and out of the cell by diffusion and active transport. It is also used to efficiently excrete or remove waste from the cells to avoid cellular damage. 4. They have a central vacuole and a cell wall to keep the organelles in place and keep the ratio intact. 5. a. Root hairs expands itself by absorbing water and nutrients through osmosis. Changing the surface area over volume ratio. b. Alveoli provide increased surface area for gas exchange due to their small size, clustered shape, and general abundance in the lungs. They can expand themselves to a certain limit to take in oxygen. c. The small intestine is used for re-absorption of nutrients. The small intestine's wall is covered with villi. These villi increases the surface area of the intestine, so that more nutrients can be absorbed into the body. d. Microvilli are cellular membrane protrusions that increase surface area for diffusion but also minimizes any increase of volume to do its functions.