How can agar be used to represent diffusion?
Use cubes of agar to investigate how size impacts diffusion. All biological cells require the transport of materials across the plasma membrane into and out of the cell. By infusing cubes of agar with a pH indicator, and then soaking the treated cubes in vinegar, you can model how diffusion occurs in cells.
What evidence is there that Naoh diffuses into an agar cube?
3a) What evidence is there that the sodium hydroxide diffuses into the agar? We know the sodium hydroxide diffuses into the agar cube because the cube turned purple as it entered the cube containing the phenolphthalein, an indicator of base.
Why did the diffusion of iodine into the potato cube cause the color change from white to black?
Background. When potatoes are immersed in a iodine solution, the potatoes start to have a dark navy color. This change of color represents reaction between iodine and starch, which is a substance that potatoes contain.
Why are agar cubes used as model cells?
The agar cubes represent biological cells. The volume of the cube correlates to the cytoplasm and the surface area of each cube to the cell membrane. All living cells are dependent on diffusion processes for survival. These processes transport materials across the cell membrane into and out of the cell.
How do you make agar cubes for diffusion?
Diffusion
- Mix 20g of agar with one liter of distilled or deionized water. Recipe based on 15 groups of students working in pairs.
- Heat almost to a boil. Stir frequently until solution is clear.
- Remove from heat.
- Pour agar into a shallow tray to a depth of 3cm and allow it to set (over night).
What is the process of diffusion?
diffusion, process resulting from random motion of molecules by which there is a net flow of matter from a region of high concentration to a region of low concentration. A familiar example is the perfume of a flower that quickly permeates the still air of a room.
How do cells get rid of waste?
Cells use both diffusion and osmosis to get rid of their wastes. Cells can bias the movement of waste molecules out of and away from themselves. One way is to temporarily convert the waste product into a different molecule that will not diffuse backwards.
Why do cells have size limits?
The need to be able to pass nutrients and gases into and out of the cell sets a limit on how big cells can be. The larger a cell gets, the more difficult it is for nutrients and gases to move in and out of the cell. As a cell grows, its volume increases more quickly than its surface area.
Why does diffusion occur?
Diffusion occurs when particles spread. They move from a region where they are in high concentration to a region where they are in low concentration. Diffusion happens when the particles are free to move. This is true in gases and for particles dissolved in solutions – but diffusion does not occur in solids.
What is the relationship between SA v ratio and diffusion time?
Explanation: When the cell increases in size, the volume increases faster than the surface area, because volume is cubed where surface area is squared. When there is more volume and less surface area, diffusion takes longer and is less effective.
How do you use cubes of agar to study diffusion?
Use cubes of agar to investigate how size impacts diffusion. All biological cells require the transport of materials across the plasma membrane into and out of the cell. By infusing cubes of agar with a pH indicator, and then soaking the treated cubes in vinegar, you can model how diffusion occurs in cells.
How does vinegar diffuse on agar agar?
Diffusion occurs when molecules in an area of higher concentration move to an area of lower concentration. As hydrogen ions from the vinegar move into the agar cube, the color of the cube changes allowing you to see how far they have diffused.
How can I model how diffusion occurs in cells?
Use cubes of agar to investigate how cell size impacts diffusion. All biological cells require the transport of materials across the plasma membrane into and out of the cell. By infusing cubes of agar with a pH indicator, and then soaking the treated cubes in vinegar, you can model how diffusion occurs in cells.
How does agar cube size affect surface area to volume ratio?
This shows that there is a negative correlation with reaction rate and surface area to volume ratio. Larger agar cube sizes also result in lower surface area to volume ratios, as when size increases, the surface area increases by a lower factor when compared against the increase in volume, thus reducing surface area to volume ratio.