Which of the following is the function of heartwood?

Select the wrong statements.
$I.$ Primary and secondary phloem gets crushed during secondary growth.
$II.$ During secondary growth,primary xylem remains more or less intact.

Vascular cambium is a meristematic layer that cuts off

The anatomy of springwood shows some peculiar features. Identify the correct set of statements about springwood.
$(a)$ It is also called as the earlywood
$(b)$ In spring season cambium produces xylem elements with narrow vessels
$(c)$ It is lighter in colour
$(d)$ The springwood along with autumnwood shows alternate concentric rings forming annual rings
$(e)$ It has lower density
Choose the correct answer from the options given below:

Age of a tree can be estimated by

In heartwood,the conduction of sap is mostly blocked due to the presence of: