Which of the following statements is true?
a. Archaea and bacteria have identical membrane lipids
b. The cell walls of archaea lack peptidoglycan
c. Prokaryotes have low levels of genetic diversity
d. No archaea are capable of using CO₂ to oxidize H₂, releasing methane

Verified step by step guidance

1. Step 1: Begin by analyzing the structure and composition of membrane lipids in archaea and bacteria. Archaea have unique membrane lipids composed of ether linkages, while bacteria have membrane lipids with ester linkages. This makes statement 'a' incorrect.
2. Step 2: Examine the composition of cell walls in archaea. Unlike bacteria, archaea lack peptidoglycan in their cell walls and instead have pseudopeptidoglycan or other polymers. This makes statement 'b' correct.
3. Step 3: Evaluate the genetic diversity of prokaryotes. Prokaryotes, including archaea and bacteria, exhibit high levels of genetic diversity due to mechanisms like horizontal gene transfer, mutations, and rapid reproduction. This makes statement 'c' incorrect.
4. Step 4: Investigate the metabolic capabilities of archaea. Some archaea, such as methanogens, are capable of using CO2 to oxidize H2, releasing methane as a byproduct. This makes statement 'd' incorrect.
5. Step 5: Conclude that the correct answer is statement 'b', based on the analysis of cell wall composition in archaea.

Key Concepts

Differences between Archaea and Bacteria

Archaea and bacteria are both prokaryotic organisms, but they differ significantly in their cellular structures and biochemistry. For instance, the membrane lipids of archaea contain ether bonds, while bacteria have ester bonds. Additionally, the composition of their cell walls varies, with archaea lacking peptidoglycan, a key component found in bacterial cell walls.

Prokaryotic Cell Walls

Prokaryotic organisms, including bacteria and archaea, have distinct cell wall structures that provide shape and protection. While bacterial cell walls are primarily composed of peptidoglycan, archaeal cell walls can be made of various materials, such as pseudopeptidoglycan or proteins, and do not contain peptidoglycan at all. This difference is crucial for understanding the classification and characteristics of these organisms.

Genetic Diversity in Prokaryotes

Prokaryotes, which include both bacteria and archaea, exhibit a high level of genetic diversity despite their simple structure. This diversity arises from mechanisms such as horizontal gene transfer, mutations, and rapid reproduction rates. Contrary to the statement in the question, prokaryotes are known for their adaptability and genetic variation, which can lead to significant evolutionary changes.