Which cellular structure do eukaryotic cells have l, but prokaryotic cells lack ?

Eukaryotic cells have a nucleus, a membrane-bound chamber where DNA is stored, while prokaryotic cells don't. This is the feature that formally separates the two groups. Eukaryotes usually have other membrane-bound organelles in addition to the nucleus, while prokaryotes don't.

Explanation:

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it cools slower in the earth meaning the crystals have more time to form than lava on the surface

answer; both surfaces of the membrane are nonpermeable