The cambium which produces cork is known as

What is/are true about heartwood?

$I.$ It does not help in water conduction.

$II.$ It is also called alburnum.

$III.$ It is dark in colour but very soft.

$IV.$ It has tracheary elements, which are filled with tannin, resin, etc.

Cambium activity is

The vascular cambium in dicots is

In woody dicotyledons, the arrangement of vessels is either diffuse porous or ring porous. Based on the these data, which one of the following statements is correct ?

What is meant by secondary growth ? Which are its type ?