10.At maturity, which of the following is enucleate? A. Sieve cell B. Palisade cell C. Companion cell D. Cortical cell
Option A Sieve tube cells are closely associated with the companion cells through the plasmodesmata. Initially, they have a nucleus but at maturity lose the nucleus, ribosomes, and vacuoles and get differentiated for the translocation of food. The nuclei of the companion cells control the activities of the sieve tube cells through the plasmodesmata. Hence, although the mature sieve tube cells are enucleated, they remain living.
