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A pteridophyte is a vascular plant (with xylem and phloem) that reproduces by means of spores.Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as "cryptogams", meaning that their means of reproduction is hidden.
In the large genus Cladonia, the prothallus may provide a mode of vegetative reproduction, and it may have a role in stabilising the soil. [3] In some genera, such as Coenogonium , the presence of absence of prothalli is an important taxonomic character that is used to help classify species. [ 4 ]
A male zygote develops by mitosis into a microsporophyte, which at maturity produces one or more microsporangia. Microspores develop within the microsporangium by meiosis. In a willow (like all seed plants) the zygote first develops into an embryo microsporophyte within the ovule (a megasporangium enclosed in one or more protective layers of ...
Three types of cell division: binary fission (taking place in prokaryotes), mitosis and meiosis (taking place in eukaryotes).. When cells are ready to divide, because cell size is big enough or because they receive the appropriate stimulus, [20] they activate the mechanism to enter into the cell cycle, and they duplicate most organelles during S (synthesis) phase, including their centrosome.
The hyper phosphorylation of Rb is considered the late G1 restriction point, after which the cell cannot go backwards in the cell cycle. At this point, E2F 1-3 proteins bind to DNA and transcribe Cyclin A and Cdc 6. [11] Cyclin-dependent kinase inhibitor 1B (CDKN1B), also known as p27, binds to and prevents the activation of CyclinE:Cdk2 by ...
The cell cycle in eukaryotes: I = Interphase, M = Mitosis, G 0 = Gap 0, G 1 = Gap 1, G 2 = Gap 2, S = Synthesis, G 3 = Gap 3. Cell division is the process by which a parent cell divides into two daughter cells. [1] Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing.
The production of gemmae is a widespread means of asexual reproduction in both liverworts and mosses. In liverworts such as Marchantia, the flattened plant body or thallus is a haploid gametophyte with gemma cups scattered about its upper surface. The gemma cups are cup-like structures containing gemmae.
Lycopodielloideae is a subfamily in the family Lycopodiaceae in the Pteridophyte Phylogeny Group classification of 2016 (PPG I). [1] It is equivalent to a broad circumscription of the genus Lycopodiella in other classifications. Like all lycophytes, members of the Lycopodielloideae are vascular plants that reproduce by spores.