question_answer 29)

  What is the fate of primary xylem in a dicot root showing extensive secondary growth? (a) It is retained in the centre of the axis               (b) It gets crushed (c) May or may not get crushed                                 (d) It gets surrounded by primary phloem

Answer:

                  (d)PhellogenIt is secondary meristematic tissue which develops from the cells ofcortical region of dicot stem. It is responsible for secondary growth. It's cells divide onboth sides, i.e., anticlinal division occurs. On the outer side of stem, it gives rise to cork or phellem and on inner side phelloderm or secondary cortex.