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.

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## What do the agar cubes represent in this lab?

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.

## How can you determine the rate of diffusion in the agar cubes?

Calculating % diffusion in each cube: (That is, calculate total volume of the small portion of the cube that did not turn pink – use the same formula L x W x H) Calculate volume diffused = total volume – volume not pink. Calculate % diffusion = Volume diffused /total volume x 100.

**What are agar cubes?**

Agar cubes are prepared in three sizes (approximately 1cm, 2cm, and 3 cm). Phenolphthalein has been added to the cubes to exhibit a vivid fuchsia color during production and stored in a solution of sodium hydroxide. Just add an acid such as vinegar to demonstrate diffusion.

### How do you do agar well diffusion test?

In this well-known procedure, agar plates are inoculated with a standardized inoculum of the test microorganism. Then, filter paper discs (about 6 mm in diameter), containing the test compound at a desired concentration, are placed on the agar surface. The Petri dishes are incubated under suitable conditions.

### How do you use cubes of agar to study diffusion?

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 do you cut agar agar?**

Spoon/Tongs Procedure Each group will cut three agar cubes: A 3cm cube, a 2cm cube, and a 1cm cube. CUT AS ACCURATELY AS POSSIBLE. (This may be already completed for you.) Pour 200mL of 0.1M sodium hydroxide solution into your 400mL beaker. Immerse your 3 cubes in the sodium hydroxide solution, noting the time.

## How does the size of agar cube affect the surface area?

As the size of the agar cube increases, both the surface area and volume directly increase, but the volume increases at a higher factor than the surface area, leading to a lower surface area to volume ratio as the size of the agar cube increases.

## 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.