How many half-lives have passed if a rock contains 25% parent isotopes and 75% daughter isotopes?

Answer: The cell would lack genetic information.

Explanation:

A eukaryotic cell is the one which has a membrane-bound nucleus containing the organisms genetic information in contrast to prokaryotic cells where a true nucleus is absent. Therefore if a student would remove the nucleus from a eukaryotic cell, the cell would lack the genetic information and the procedure would fail. Besides this, the eukaryotic cell also contains other membrane-bound organelles such as the mitochondria which are absent in prokaryotic cells. Thus, just removing the nucleus is not enough to convert a eukaryotic cell to prokaryotic.