Govt. Exams
Entrance Exams
Heterospory (production of two types of spores - microspores and megaspores) is found in lycopsids and seed plants, representing advanced evolution.
The nucellus is the megasporangium of the ovule and represents the tissue where megasporogenesis occurs.
Endosperm is a nutritive tissue produced by triple fusion nuclei, stores nutrients (starch, protein, oils) and nourishes the developing embryo during seed maturation and germination.
The integument (outer layer of ovule) develops into the testa (seed coat) after fertilization, protecting the developing embryo.
Wind-pollinated flowers are typically small, inconspicuous, and produce copious amounts of light, dry pollen that can be easily dispersed by wind.
Anthers develop from microsporophylls (stamens) and contain four pollen sacs (microsporangia) where microspores develop into pollen grains.
The mature female gametophyte (embryo sac) in angiosperms is typically 7-celled with an egg apparatus (1 egg + 2 synergids) and 3 antipodal cells.
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.
