Govt Exams
Angiosperms have stationary male gametes (non-motile sperm). Motile sperms are primitive characters found in bryophytes and some gymnosperms.
Sieve tube elements and companion cells are the conducting and supporting elements of phloem tissue in angiosperms for translocation of organic solutes.
Double fertilization: one sperm fuses with egg nucleus → zygote (diploid); second sperm fuses with central cell → endosperm (triploid). Unique to angiosperms.
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.
Gymnosperms (Conifers, Cycads, Ginkgo) have seeds exposed on cone scales without floral structures or fruit coverings.
Selaginella is a pteridophyte - it has vascular tissue but reproduces via spores, not seeds. Pinus is a gymnosperm with seeds.
A sorus (plural: sori) is a cluster of sporangia found on the underside of fern fronds, typically covered by an indusium.
The prothallus is the gametophyte of ferns - a small, green, heart-shaped structure that is photosynthetically active and independent.