Govt Exams
Apomixis is asexual reproduction in seeds where offspring are genetically identical to the parent, bypassing meiosis and fertilization.
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.
Gymnosperms produce naked seeds not enclosed in a fruit and lack true flowers. Angiosperms have enclosed seeds within fruits and possess flowers.
Xylem in pteridophytes consists of tracheids and vessels. Companion cells are found only in angiosperms associated with phloem.
Bryophytes have a dominant gametophytic generation, while the sporophyte is dependent on the gametophyte. This is unique among land plants and represents their primitive nature.
Bryophytes produce both archegonia (female) and antheridia (male), allowing sexual reproduction; pteridophytes, gymnosperms also have these, but bryophytes are distinctively defined by them.