Question

root words karyo comes from the greek karyon, meaning
ut\ or \kernel.\ it is used in words that refer to the nucleus. pro- is a prefix that means \before,\ so prokaryotes have been around since before the nucleus appeared in living organisms. what structure distinguishes eukaryotes from prokaryotes?

Explanation:

Prokaryotes lack a true nucleus, while eukaryotes have a membrane - bound nucleus. This is the key structural difference.

Answer:

A membrane - bound nucleus.