Explain ihe following:
(i) Sporophyll (ii) Antheridium
(iii) Archegonium (iv) Isogamy
(v) Diplontic.
(i) Sporophyll: Spores bearing leaves of ferns are called as sporophylls. Sporangia occcur on the leaves on clusters called sori, so they are also known as fertile leaves. A sorus is covered by a flap-like outgrowth from its surface or turned margins of sporophyll. They are of two types: microsporophyll which bear microsporangia and megasporophyll which bear megasporangia.
(ii) Antheridium : Male sex organs in bryophytes and pteridophytes are known as Antheridium. They are jacketed and multicellular which produces a number of flagellated male gametes called sperms or antherozoids.
(iii) Archegonium : The female sex organs of bryophytes, pteridophytes and gymnosperms and called as archegonia. It is a flask shaped structure with tubular neck and a swollen venter. The single layered wall of neck has 5-6 rows of cell. It encloses a few sterile neck canal cells. The walls of venter encloses a few sterile venter canal cell and a fertile egg or oosphere.
(iv) Isogamy : In isogamy the fusing gametes are morphologically and physiologically similar. They may be flagellate or non-flagellate.
(v) Diplontic : It is a type of life cycle that occurs in green algae. In this life cycle, the dominant phase of algae is diploid (2n). It give rise to haploid gametes, through meiosis. The gametes fuse and the fusion produces zygote that regenerates the diploid phase.