Question

Bordered pits are very common among tracheids of

• A. Monocotyledons
• B. Dicotyledons
• C. Pteridophytes
• D. Gymnosperm

Answer 1

Answer: (D)

Gymnosperm

During cell wall thickening, deposition of lignin covers the whole primary cell wall of tracheid, except at gaps termed as bordered pit-pairs. The pit pairs represent the small regions of un-lignified primary wall from two adjacent cells and are concentrated at end walls between cells, forming a pitted region called as pitted end walls. A pit pair shares a common membrane of primary wall and middle lamella and the raised wall around the pit aperture serve as border. Presence of bordered pits is considered as primitive character which has evolved into lateral, alternate pits as found in flowering plants. Since, gymnosperms are primitive to angiosperms (monocots and dicots), they have more abundant bordered pits. Since, pteridophytes are the first vascular plants, less advanced than gymnosperms, they have less developed bordered pits.
Therefore, the correct answer is option D.