Question
Question: Both pteridophytes and gymnosperms have ______________. (a)Seeds (b)Independent gametophytes ...
Both pteridophytes and gymnosperms have ______________.
(a)Seeds
(b)Independent gametophytes
(c)Archegonia
(d)Ovules
Solution
Pteridophytes are vascular cryptogams widely distributed all over the world. Gymnosperms are seed-bearing plants without flowers. Both of them possess the female sex organ. It is a multicellular structure of the gametophyte phase of certain plants. It produces female gametes.
Complete answer:
Pteridophytes and certain Gymnosperms have Archegonia as the female reproductive structure. It is a multicellular flask-shaped structure. It is differentiated into a broad base i.e the center that contains the egg and an elongated neck containing the neck canal cells. The narrow opening of the neck is covered by cover cells. In Pteridophytes the Archegonium consists of only the neck, center being absent. The neck usually projects from the surface of the prothallus. It contains one or two neck canal cells. Egg and center canal cells remain surrounded by the cells of the prothallus. While in the case of gymnosperms the number of Archegonia may vary. There are several Archegonia in cycas and only one in pinus. The Archegonium of Gnetum is represented by ovum only. Archegonium has a single egg and a center canal cell. There are no neck canal cells.
Additional Information: -Gymnosperms are heterosporous. Megasporangia and microsporangia occur on mega and microsporophylls respectively. These sporophylls usually aggregate to form compact vibes and strobili.
-Sex organs of Pteridophytes include Archegonia or female organs and antheridia or male organs. Antheridia are generally sessile, with a single-layered jacket which encloses a mass of androgonial cells.
-Androgonial cells give rise to androcytes which, in turn, form flagellated and motile antherozoids.
So, the correct answer is 'Archegonia'
Note:
- Pteridophytes are taxonomically intermediate between Bryophytes and phanerogams.
-They possess a combination of certain features which are absent in Bryophytes and phanerogams.
-Gymnosperms are the most ancient group of seed plants. Most of the living gymnosperms are evergreen trees or shrubs with xerophytic adaptations.