Q. Which of the following statements are true? I.Uneven thickening of cell well is characteristic of sclerenchyma. II.Periblem forms the cortex of the stem and the root. III.Tracheids are the chief water transporting elements in gymnosperms. IV.Companion cell is devoid of nucleus at maturity. V.The commercial cork is obtained from Quercus suber.
A) I and IV
B) II and V
C) III and IV
D) II, III and V
Explanation
Sclerenchyma is composed of dead cells. The cell wall is heavily thickened due to deposition of lignin. According to histogen theory, periblem is the middle dermatogen, which gives rise to cortex of root and stem. Tracheids are most primitive type of conducting elements in xylem. The xylem of gymnosperms consists of tracheids only. Companion cells are thin-walled elongated cells in phloem. They are living, contain dense protoplasm and large elongated nucleus. Cork is produced by a number of plants. However, it is commercially obtained from the cork oak tree (Quercus suber).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.