How do the phospholipids in archaea differ from those in other cells? a. They have tails made of unsaturated fatty acids instead of saturated fatty acids. b. They do not contain hydrocarbon chains. c. They have isoprenoid tails instead of fatty acid tails. d. They have two hydrocarbon chains instead of three hydrocarbon chains.

Step 3: Evaluate each of the given options. Option a suggests that archaeal phospholipids have tails made of unsaturated fatty acids instead of saturated fatty acids. Option b suggests that they do not contain hydrocarbon chains. Option c suggests that they have isoprenoid tails instead of fatty acid tails. Option d suggests that they have two hydrocarbon chains instead of three.

Step 4: Recall that the key difference between archaeal phospholipids and those in other cells is in the nature of their tails. Archaeal phospholipids have isoprenoid tails, which are made up of repeating five-carbon units, instead of the fatty acid tails found in other cells.