Question

Sieve tubes are characterised by:

• A. Absence of septa
• B. Perforated oblique septa
• C. Perforated longitudinal walls
• D. Simple oblique septa

Answer 1

The correct option is B

Perforated oblique septa

Sieve plate (oblique transverse perforated septa) is present between the two sieve tube elements at their end wall. It is porous. Materials are transported through these pores. Callose deposited on the radius of pores during dropping season (autumn) of leaves, to form a thick layer. This is called Callus pad.