What is a difference between prokaryotic and eukaryotic cells? a. prokaryotic cells do not have a nucleus, but eukaryotic cells do. b. eukaryotic cells do not have membrane-bound organelles, but prokaryotic cells do. c. prokaryotic cells always have cell walls, but eukaryotic cells do not. d. organisms with eukaryotic cells are always multicellular, but organisms with prokaryotic cells are not.

Prokaryotic cells do not contain a nucleus or any other membrane-bound organelle. Eukaryotic cells contain membrane-bound organelles, including a nucleus. So I belive the answer is A :P Hope it helps

the element that provides strength to the exoskeletons of clams and oysters is phosphorus.

this is so because calcium carbonate is the main component in the shells. calcium carbonate is strengthened by phosphorus.

explanation: