======Agar Cubes Diffusion ======


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**Alternative titles:** Agar Cell Diffusion 
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====Summary====                   
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====Procedure====  
  - Prepare agar solution by mixing agar-agar powder with water, heating in a microwave until it boils, then adding a pH indicator (bromothymol blue or phenolphthalein) and ammonia to achieve a strong color.  
  - Pour the agar into molds or a dish to solidify into blocks at least 3 cm deep.  
  - Cut the solid agar into cubes of three sizes: 1 cm³, 2 cm³, and 3 cm³. Prepare one untreated set and one set for vinegar soaking.  
  - Place one cube of each size into vinegar in a clear container, ensuring full submersion. Keep a matching untreated cube for comparison.  
  - After 5 minutes, remove the cubes and compare the depth of color change with untreated cubes. Estimate how far vinegar has penetrated.  
  - Return cubes to vinegar and repeat observations every 5 minutes until diffusion is complete.  
  - Calculate surface area, volume, and surface-area-to-volume ratio for each cube and relate to observed diffusion rates.




====Links==== 
Agar Cube Surface Area - Southern Biological: 
{{youtube>4U8cTfng3tk?}}\\

Surface Area to Volume Ratio Diffusion Practical with Agar - Science4Breakfast: 
{{youtube>wGwMH037YrI?}}\\

📄 Agar Cell Diffusion - Science Snack: [[https://www.exploratorium.edu/snacks/agar-cell-diffusion]]\\



====Variations====
  * Try different shapes (spheres, rods) using molds to see how cell shape affects diffusion.  
  * Use red cabbage juice as a low-cost alternative to pH indicators.  



====Safety Precautions====
  * Use oven mitts or hot pads when handling hot agar solution.  
  * Handle knives carefully when cutting agar cubes.  
  * Work on a heatproof surface.  
  * Clean spills promptly to avoid slipping hazards.




====Questions to Consider====
  * Which cube size allowed the fastest penetration of vinegar? Why?  
  * How does surface-area-to-volume ratio explain the differences in diffusion times?  
  * Why do larger biological cells require additional structures (e.g., endoplasmic reticulum) to move materials efficiently?  
  * What would happen if cells continued to grow larger without adaptations?  
  * How might different shapes of cells (not just cubes) affect diffusion rates?