Diffusion in agar cubes
Introduction: All cells are dependent on a processes called diffusion, which is the movement of a substance from an area of higher concentration to an area of lower concentration. Cells need to obtain certain essential substances, like oxygen, for their survival. The rate of diffusion is said to be dependent upon the various factors: Size of molecules that have to diffuse, concentration gradient, the distance across which diffusion occurs, number of pores/openings, surface area and concentration.
This rate of diffusion is measured by considering the time taken for changes to physical changes to occur. This experiment consists of using agar mixed with an indicator that changes color when places in a basic solution. It will measure the amount of diffusion that occurs in the agar blocks to determine the effect of cell size on the cell’s ability to obtain substances by diffusion.
Purpose:Determine how surface area and volume relate to one another and how the rate of diffusion varies with the ratio of surface area to volume. In the experiment, we will use the base/acid indicator Phenolphthalein in three different sized agar cubes dipped in a sodium hydroxide solution. This will make it possible to measure the depth to which the color has penetrated and will demonstrate the relationship between diffusion and volume.
-two large beakers
-Potassium manganate (K2MnO4 )
-Hydrogen chloride (HCl)
-Make two trays of Agar Gelatin. One pure and one dyed pink. -Use the scalpel to cut three agar cubes of each tray: a 3cm cube, a 2cm cube and a 1cm cube (total of six cubes). -Pour the Potassium manganate (K2MnO4 ) into one of the beakers and Hydrogen chloride (HCl) in the other. -Immerse the 3cm clear cube in the pink Potassium manganate (K2MnO4 ) and the pink agar cube in the clear Hydrogen chloride (HCl).
-Set the timer to 10 minutes.
-After the 10 minutes, use the spoon to take the cubes out of the beakers and dry them with a paper towel. -Cut both cubes in half with the scalpel.
-With the ruler, measure how deep the pink penetrated the clear cube and how much the pink cube absorbed the acid. -Repeat the procedure with the smaller cubes, always leaving them in the beaker for 10 minutes.
It’s clear to see that the cubes in which most of their volume changed color were the smaller ones. The 1cm Clear cube had 100% of it’s volume diffused. The smaller agar cubes will be more efﬁcient in diffusion because smaller agar cubes have a bigger surface area to volume ratio. The pink agar cubed immersed in Hydrogen chloride (HCl) had a faster process of diffusion than the clear agar cube immersed in Potassium manganate (K2MnO4 ).
The reason cells are so small is because it facilitates the diffusion. As seen in the experiment, diffusion is more efﬁcient when there is a bigger surface area to volume ratio. This process is essential for every cell to bring nutrients and release wastes and it is only possible due to the fact that cells are very small, making the diffusion a lot faster.
Osmosis and Diffusion Lab Report Introduction All Cells Contain Membranes That Are Selectively Permeable, Allowing Certain Things to Pass Into and Leave Out of the Cell. the Process in Which Molecules of a Substance
1016 WordsOct 18th, 20125 Pages
All cells contain membranes that are selectively permeable, allowing certain things to pass into and leave out of the cell. The process in which molecules of a substance move from an area of high concentration to areas of low concentration is called Diffusion. Whereas Osmosis is the process in which water crosses membranes from regions of high water concentration to areas with low water concentration. While molecules in diffusion move down a concentration gradient, molecules during osmosis both move down a concentration gradient as well as across it. Both diffusion, and osmosis are types of passive transport, which do not require help.
When the concentration of the environment outside of the cell is lower than the inside…show more content…
However one beaker received 100 mL of Deionized water with a molarity of 0.0. Afterwards a cork borer was pushed through the potato and was twisted back and forth. Once the borer was filled it was removed from the potato. Pushing the potato cylinder out of the borer, this this step was repeated six more times in order to get seven undamaged potato cylinders. Using a sharp razor blade, the potato cylinders were both cut to a uniform length of about 5cm, and were removed of their potato skins. The potato pieces were also cut in half to give the cells a greater surface area in which it was easier to absorb the solution. After the cylinders were weighed on a balance and the data was recorded in Table 4. Using the razor blade each potato was cut lengthwise into two long halves. Then the potato pieces were transferred to the water beaker and the time they were submerged was recorded. This step was repeated for all potato cylinders in which the pieces were placed in solutions 0.1 to 0.6 M. The potatoes were incubated for ninety minutes. At the end of the incubation period the time was recorded. Then the potato piece was removed form the first sample. Next potato pieces were weighed the and the final weight was recorded in Table 4. This procedure was repeated until all samples had been weighed and recorded in the chronological order they were initially placed in the test solution. Afterwards the table was completed by recording the