Question

how eukaryotic cells avoid
limitations of rates of diffusion

Answer 1

Eukaryotic cells are generally much larger than prokaryotic ones and this difference in volume has several implications. First bigger cells can afford to have more things stored in the cytoplasm. This means it is not as costly to a eukaryotic cell to have structures taking up space. In a prokaryote, space is at a premium and anything not being used is pretty rapidly degraded. This may be one reason that organelles are possible. Second, larger cells have a lower surface-to-volume ratio than do smaller cells and therefore prokaryotes effectively have more contact with their environment. This greater exposure can mean a more rapid response to changing environmental conditions. Finally bigger cells have more of a challenge moving molecules within themselves. Prokaryotes can often depend on simple diffusion to move molecules around the cell, but this process might be too slow and inefficient in much larger cells. Eukaryotes overcome this by having specific transport mechanisms (i.e. microtubules) inside the cell.