Though plants, fungi, and prokaryotes all have cell walls, we place them in different taxa. Which of these observations comes closest to explaining the basis for placing these organisms in different taxa, well before relevant data from molecular systematics became available?
A) Some closely resemble animals, which lack cell walls.
B) Their cell walls are composed of very different biochemicals.
C) Some have cell walls only for support.
D) Some have cell walls only for protection from herbivores.
E) Some have cell walls only to control osmotic balance.

Question

Quizplus · Accepted Answer

The composition of the cell wall is a major factor in the classification of these organisms. Plants have cell walls made of cellulose, fungi have cell walls made of chitin, and prokaryotes have cell walls made of peptidoglycan. This fundamental difference in biochemical composition is a significant factor in their placement in different taxa.

Though Plants, Fungi, and Prokaryotes All Have Cell Walls, We