Life Cycle of Bryophytes
The plants reproduce sexually through gametes and hence they are called gametophytes. Bryophytes are spore-producing plants. The sex organs are multicellular and present on the thallus of the plant. Archegonium is the female sex organ, it is a flask-shaped multicellular structure present on the thallus of the plant consisting of a single egg cell (Female gamete) and it is non-motile. The part on which the female sex organ is present is known as the Female gametophyte. Antheridium is the male sex organ and its presence classifies the part as a Male gametophyte. When both the male and female sex organs are present on the same thallus then it is termed a Bisexual Thallus or Bisexual Gametophyte. The gametophyte is haploid, therefore the Archegonium and Antheridium are haploid too. Antheridium produces male gametes known as antherozoids which have two flagella (Biflagellate) and are motile. The antherozoids move through the water and when they come in contact with the archegonium, internal fertilization takes place and a fusion between antherozoids and egg occurs, which produces a diploid zygote. The zygote remains in the archegonium, then undergoes mitotic cell division and develops into a diploid embryonic sporophyte. The growing embryo is covered by a structure called calyptra. The sporophyte is dependent on the gametophyte for nutrition. The cells in sporophyte undergo meiosis and produce haploid spores. When the spores germinate, they go through mitosis and produce new gametophytes.
Bryophytes | Class 11 Biology
Living organisms are classified into five different categories based on their methods of nutrition, cellular structure, modes of reproduction, body composition, etc. R.H. Whittaker gave the Five Kingdom classification. The five kingdoms are Monera, Protista, Fungi, Plantae, and Animalia.
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