Question

In Pteridophyta and gymnosperms, which cells are present in place of companion cells?
A. Sclereids
B. Albuminous cells
C. Idioblasts
D. None of the above

Answer 1

Hint: Pteridophytes are vascular plants with xylem and phloem that disperses spores. Pteridophytes do not produce flowers and seeds. They show the true alternation of generations. For example, Selaginella, Lycopodium, Equisetum, Pteris, Whisk Fern, Dryopteris, etc. Gymnosperms are plants that are flowerless and produce seeds and cones. The seeds are not encased within an ovary. Examples of gymnosperms are pines, firs, spruce, and ginkgoes. Companion cells are the cells that are found within the phloem of flowering plants. The function of companion cells is transportation.

Complete answer:
1. In Pteridophyta and gymnosperms, cells that are found in place of companion cells are albuminous cells.
2. Albuminous cells are long, slender, and conducting cells of the phloem.
3. Albuminous cells are storage cells present in pteridophytes and gymnosperms stem. These cells store minerals as well as starch.
4. Albuminous cells are also known as Strasburger cells. They lack starch and this makes it possible to differentiate them from phloem parenchyma.
5. Sclereids form small bundles of durable layers of tissue in the plants.
6. Idioblasts are specialized plant cells that are different from neighboring cells. They perform various functions such as storage of reserves, minerals, pigments, and excretory material.

Hence, the correct answer is option (B).

Additional information:
1. Albuminous cells do not arise from the same mother cell.
2. These are the specialized parenchyma cells adjacent to the sieve cells in gymnosperm wood and contain albumin protein.
3. In gymnosperms, sieve tubes are absent instead they have sieve cells for conduction of food material.
4. The seeds are not encased within an ovary, but they sit exposed on the surface of leaf-like structures known as bracts.

Note: Pteridophytes are vascular plants with xylem and phloem that disperses spores. Pteridophytes do not produce flowers and seeds. Gymnosperms are plants that are flowerless and produce seeds and cones. In Pteridophyta and gymnosperms, cells that are found in place of companion cells are albuminous cells. Albuminous cells are storage cells found in pteridophytes and gymnosperms stem. These cells store minerals as well as starch.