Which statement about archaea is true?

Which statement about archaea is true?

• A. They lack peptidoglycan in their cell walls.
• B. They are known to cause many human diseases.
• C. They are true nucleus-bearing organisms.
• D. They all perform photosynthesis using chlorophyll.

Answer: (A)

Archaea differ from bacteria in the composition of their cell walls. They generally do not with peptidoglycan; instead, their walls are built from materials such as pseudopeptidoglycan or various proteins and glycoproteins in an S-layer. This fundamental difference is why the statement about lacking peptidoglycan is true: archaea rely on a distinct cell wall chemistry, which also helps explain why antibiotics that target bacterial peptidoglycan don’t affect archaea. For broader context, bacteria commonly use peptidoglycan to maintain cell shape and integrity, whereas archaea have different structural targets. The other statements aren’t accurate: archaea are not known to cause human diseases; they do not possess a true nucleus; and chlorophyll-based photosynthesis isn’t a general trait of archaea—some capture light energy with retinal-based pigments instead of chlorophyll.

Archaea differ from bacteria in the composition of their cell walls. They generally do not with peptidoglycan; instead, their walls are built from materials such as pseudopeptidoglycan or various proteins and glycoproteins in an S-layer. This fundamental difference is why the statement about lacking peptidoglycan is true: archaea rely on a distinct cell wall chemistry, which also helps explain why antibiotics that target bacterial peptidoglycan don’t affect archaea. For broader context, bacteria commonly use peptidoglycan to maintain cell shape and integrity, whereas archaea have different structural targets. The other statements aren’t accurate: archaea are not known to cause human diseases; they do not possess a true nucleus; and chlorophyll-based photosynthesis isn’t a general trait of archaea—some capture light energy with retinal-based pigments instead of chlorophyll.