[Campbell Biology P.167] Regarding the structure and development of plant cell walls, which ... | Practice Question
Regarding the structure and development of plant cell walls, which of the following statements is correct?
A: The middle lamella is a thick, rigid layer primarily composed of cellulose that provides the main structural support for mature plant cells.
B: Young plant cells first secrete a relatively thin and flexible primary cell wall, and later, some cells add a secondary cell wall between the plasma membrane and the primary wall for strengthening.
C: Wood primarily consists of primary cell walls because they are deposited in several laminated layers, providing strong and durable support.
D: Cellulose microfibrils are synthesized in the extracellular space by the enzyme cellulose synthase.
Explanation
Young plant cells initially secrete a primary cell wall, which is thin and flexible, allowing for growth. As cells mature and stop growing, some develop a secondary cell wall, which is thicker and stronger, deposited between the plasma membrane and the primary wall. This process strengthens the cell wall, as seen in structures like wood, which is mainly composed of secondary walls.