Final answer:
Smaller cells have faster diffusion rates due to the shorter distance molecules must travel within them, which can limit the size of efficient functioning cells.
Step-by-step explanation:
The results of the agar blocks experiment suggest that diffusion rate is affected by cell size, with smaller cells having faster diffusion rates compared to larger cells. This is because diffusion is a process that depends on several factors, including the distance that molecules must travel. In the context of cells, a smaller cell size means a shorter distance for molecules to travel from the cell membrane to the interior and vice versa, leading to a quicker rate of diffusion.
For large cells, the increased distance that materials such as nutrients or waste must travel can slow down the diffusion rate. This can be detrimental, as materials may not reach the center of the cell in a timely manner, potentially hindering cell functions or even leading to cell death. Therefore, most cells are small or have adapted shapes, like being flattened, to allow for efficient diffusion.