Question

As a tree grows older, which of the following increases rapidly in thickness?

• A. Its heartwood
• B. Its cortex
• C. Its sapwood
• D. Its phloem

Answer 1

Answer: (A)

Its heartwood

Heartwood covers the inner circular section of the wood. As the tree grows older and new xylem tissue is added the inner xylem elements become dead due to deposition of lignin, formation of tyloses etc and does not conduct water and minerals. This keeps on increasing over years as the conducting xylem is present towards the periphery, called the sap wood. With the addition of new xylem element in the next season the sap wood in converted into heart wood

So, the correct answer is 'Its heartwood'