Question

Phloem in gymnosperms lacks :

• A. Albuminous cells and sieve cells
• B. Sieve tubes only
• C. Companion cells only
• D. Both sieve tubes and companion cells

Answer 1

The Correct Option is D

In gymnosperms, the structure of the vascular tissue, particularly the phloem, differs from that of angiosperms. The main components of phloem are sieve elements and parenchyma cells. Critical differences include:

1. Sieve Elements: Gymnosperms typically have sieve cells, which are simpler than the sieve tubes found in angiosperms. Sieve cells are associated with albuminous cells, while sieve tubes are typically associated with companion cells in angiosperms.
2. Albuminous Cells and Companion Cells: Gymnosperms have albuminous cells, which perform a similar function to the companion cells in angiosperms, but gymnosperms lack sieve tubes and companion cells.

Given the options:

• Albuminous cells and sieve cells: Present in gymnosperms as noted above.
• Sieve tubes only: Gymnosperms do not have sieve tubes.
• Companion cells only: Gymnosperms lack companion cells.
• Both sieve tubes and companion cells: Correct answer, as gymnosperms lack both structures.

The correct answer is therefore "Both sieve tubes and companion cells."

This knowledge helps in understanding the evolutionary differences and adaptations between gymnosperms and angiosperms, reflecting their different strategies for transporting nutrients.