Govt. Exams
Entrance Exams
The pollen grain is the immature male gametophyte that further develops after pollination to form the mature male gametophyte.
Cycas is a cycad and belongs to the order Cycadales, which are living fossils representing ancient gymnosperms.
Pteridophytes possess both xylem (for water conduction) and phloem (for nutrient transport), but lack the specialized sieve tubes and companion cells found in angiosperms.
Megasporophyll is the structure bearing megasporangia; in angiosperms, it corresponds to the carpel which produces megaspores.
Ferns possess true vascular tissue (xylem and phloem) and have a dominant independent sporophyte generation, making them more advanced than bryophytes.
Sieve tube elements and companion cells are the conducting and supporting elements of phloem tissue in angiosperms for translocation of organic solutes.
The embryo sac represents the female gametophyte in angiosperms, typically containing 8 nuclei in a 7-celled structure (Polygonum type).
Cycas and Ginkgo retain the primitive character of motile sperms, while other gymnosperms like Pinus have non-motile sperm.
In gymnosperms, the pollen grain is the male gametophyte. It contains generative and vegetative nuclei before pollination.
Selaginella is a pteridophyte - it has vascular tissue but reproduces via spores, not seeds. Pinus is a gymnosperm with seeds.
