Question

Which of the following statements are true regarding secondary growth in dicot root?
i. The cambial strip initially appears wavy in dicot roots.
ii. The cambium is formed by dedifferentiation of parenchymatous cells from pericycle and xylem parenchyma.
iii. The roots when transversely cut exhibit growth rings.
iv. The cambium produces secondary xylem towards inside and secondary phloem towards the outside.

• A. i and ii
• B. i, ii and iii
• C. ii, iii and iv
• D. i and iv

Answer 1

The correct option is D i and iv

During secondary growth in dicot roots the cambium is formed by dedifferentiation of parenchymatous cells of the pericycle above the protoxylem and conjunctive tissue and cells below the primary phloem. These strips then connect to give rise to a wavy cambial strip. The cells of the cambium undergo division to add secondary xylem towards inside and secondary phloem towards the outside. However, secondary growth is not seasonal in dicot roots hence, growth rings or annual rings are not formed.

So, the correct answer is ‘i and iv’.