Please answer its urgent
Solution:
The deposition of organic substances like resins, oils, tannins, gums, etc. in the innermost layers of the stem gives the secondary xylem a dark brown colour appearance. This xylem is called the heartwood. Depositions of these substances make them hard, durable, and resistant to the attacks of microorganisms. It does not conduct the water and minerals, it is made up of dead cells with highly lignified walls. The peripheral xylem is made up of functional vessels, it is called the sap wood. Hence, option (d) is correct.
The deposition of organic substances like resins, oils, tannins, gums, etc. in the innermost layers of the stem gives the secondary xylem a dark brown colour appearance. This xylem is called the heartwood. Depositions of these substances make them hard, durable, and resistant to the attacks of microorganisms. It does not conduct the water and minerals, it is made up of dead cells with highly lignified walls. The peripheral xylem is made up of functional vessels, it is called the sap wood. Hence, option (d) is correct.