Question

Sieve tubes do not have nuclei, why are they con­sidered as living cells?

Answer 1

Sieve tube:

1. Sieve tube cells are closely related to the companion cell via the plasmodesmata.
2. At the start, they possess a nucleus; however, at the prime stage they lose the ribosomes, nucleus, and vacuoles and get segregated for the conduction of food.
3. Sieve tubes are considered living cells without a nucleus because the nucleus of companion cells controls their functional activities.
4. Companion cells, which unite with sieve tubes to form the sieve element-companion cell complex, are related to sieve-tube members.
5. This enables plant cell supply and maintenance, as well as communication between distant organs inside the plant.