Govt. Exams
Entrance Exams
Pteridophytes still require water as sperm are flagellated, but the prothallus provides a moist environment. True water independence came with seeds in gymnosperms.
The suspensor absorbs nutrients from the endosperm and pushes the developing embryo deeper into the embryo sac for better nourishment.
In ferns: diploid sporophyte (2n) → meiosis → haploid spores (n) → gametophyte (n) → fertilization → sporophyte (2n).
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.
