In an introductory comparison of prokaryotes, which statement correctly describes a key difference between Bacteria and Archaea?

• A. Archaea are always multicellular, whereas Bacteria are always unicellular.
• B. Bacteria have ether-linked membrane lipids, whereas Archaea have ester-linked membrane lipids.
• C. Archaea have a nucleus enclosed by a membrane, whereas Bacteria do not.
• D. Archaea lack peptidoglycan in their cell walls, whereas most Bacteria have peptidoglycan.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the basic cellular structure of prokaryotes, which include both Bacteria and Archaea. Both groups are unicellular and lack a membrane-bound nucleus.
2. Step 2: Review the composition of cell membranes in Bacteria and Archaea. Bacteria typically have ester-linked membrane lipids, while Archaea have ether-linked membrane lipids, which is a key biochemical difference.
3. Step 3: Examine the cell wall composition. Most Bacteria have cell walls containing peptidoglycan, a polymer that provides structural support and shape.
4. Step 4: Recognize that Archaea lack peptidoglycan in their cell walls. Instead, they have other unique cell wall components such as pseudopeptidoglycan or other polymers.
5. Step 5: Conclude that the key difference highlighted in the problem is that Archaea lack peptidoglycan in their cell walls, whereas most Bacteria have peptidoglycan, making this the correct distinguishing statement.