Question

A sieve tube differs from a vessel in

• A.
  Being a conductive tissue
• B.
  Absence of cytoplasm in its cells
• C.
  Absence of lignification
• D.
  Absence of plasmodesmata

Answer 1

The correct option is C

Absence of lignification
The absence of lignified walls distinguishes a mature sieve tube from a vessel. The transport channel for water is a vessel, but the transport channel for organic materials and nutrients is a sieve tube. The walls of vessels are lignified, whereas the walls of mature sieve tubes are not. Vessels are made up of dead cells, yet living cells make up mature sieve tubes.