Question

Which of the following statements is CORRECT about a woody dicot stem which shows extensive secondary growth?

• A. The primary xylem persists in the centre of the axis.
• B. Primary and the older secondary phloem get crushed.
• C. Secondary xylem forms the bulk of the stem.
• D. All of these

Answer 1

Answer: (D)

Secondary growth is responsible for thickening the stem and roots, making them woody. This growth is a result of cell division in the cambium. When a woody dicot stem undergoes secondary growth the primary xylem (formed from the procambium) persists inside the stem in the centre of the axis without being damaged or changed during the growth. The secondary xylem is found covering the primary xylem and keeps growing in girth forming the bulk of stem. Due to this growth of the xylem during the secondary growth, the primary phloem and the older secondary phloem they get crushed towards the epidermis and form the wood.