The diagram shows the key structural components of a typical prokaryotic cell.
Which of the following statements correctly describes the composition, function, or occurrence of one of these labeled structures?
Structure W is a capsule composed of peptidoglycan (murein) that prevents desiccation and is also found in plant cell walls.
Structure X is a circular chromosome consisting of double-stranded DNA that is tightly wrapped around histone proteins, similar to eukaryotic chromosomes.
Structure Y is a plasmid, which is a small loop of double-stranded DNA that replicates independently of the genomic DNA and is absent in animal cells.
Structure Z is the cell wall, which is composed of chitin and provides structural support identical to that of fungal cell walls.