Model Answer
0 min readIntroduction
Bryophytes and pteridophytes represent crucial stages in plant evolution, bridging the gap between aquatic and terrestrial life. Bryophytes, including Riccia and Funaria, are non-vascular plants that rely on moist environments for reproduction. Pteridophytes, like Selaginella and Marsilea, exhibit vascular tissues and a more complex life cycle. Understanding their sporophyte structures is fundamental to comprehending their reproductive strategies and evolutionary adaptations. The sporophyte generation is responsible for spore production, ensuring the continuation of the species. Accurate depiction of these structures is vital for botanical studies.
(a) L.S. of Sporophyte of Riccia
Riccia’s sporophyte is relatively simple. It consists of a foot, seta, and capsule. The capsule is globose and lacks a distinct annulus. Spores and elaters are present within the capsule.
Labels: Foot, Seta, Capsule, Spores, Elaters, Operculum.
(b) L.S. of Sporophyte of Funaria
Funaria’s sporophyte is more complex than Riccia’s. It has a long seta and a capsule with a distinct operculum, peristome teeth, and an annulus. The capsule contains a central columella surrounded by spore mother cells.
Labels: Foot, Seta, Capsule, Operculum, Peristome Teeth, Annulus, Columella, Spores, Calyptra.
(c) L.S. of Strobilus of Selaginella
Selaginella’s strobilus is a cone-like structure bearing sporangiophores. Each sporangiophore bears two sporangia. The sporangia contain numerous spores. The strobilus represents the reproductive phase of the plant.
Labels: Strobilus, Sporangiophore, Sporangium, Spores, Microsporangium, Megasporangium.
(d) H.L.S. of Marsilea Sporocarp
Marsilea’s sporocarp is a thick-walled, bean-shaped structure containing sporangia and megasporangia. It develops from a modified sporophyll. The sporocarp protects the developing spores.
Labels: Sporocarp Wall, Sporangium, Megasporangium, Spores, Megaspore, Tapetum.
Conclusion
Accurate depiction of these sporophyte structures is crucial for understanding the life cycles and evolutionary relationships of bryophytes and pteridophytes. The variations in sporophyte complexity reflect the increasing adaptation to terrestrial environments. These diagrams serve as fundamental tools for botanical studies and highlight the diversity within the plant kingdom. Further research into the genetic and developmental mechanisms governing sporophyte formation continues to reveal new insights into plant evolution.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.