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Gymnosperms, Angiosperms, and the life cycle of all Plants

 Hello everyone,

Today I decided to think about the difference between Gymnosperms and Angiosperms. While Gymnosperms do have four phylum and Angiosperms one, Phylum Anthophyta/ Flowering plants compose around 250,000 known species while Gymnosperms altogether equate to around 806 known species.

The major difference between Gymnosperms and Angiosperms is that one has seeds not enclosed in chambers while the other has its seeds develop inside chambers (within flowers). With the numbers above and the inclusion of nonvascular and seedless plants, we can approximate that nearly 90% of living plant species are angiosperms.


Now let's talk about the life cycle of all plants. Plants go through a process called alternation of generations between gametophytes and sporophytes. While this does not occur in charophytes (there is always an exception to the rule in biology) this type of reproductive cycle came from green algae. Basically, the process goes as such:



  1. The gametophyte produces haploid gametes by mitosis
  2. Two gametes unite/ fuse (fertilization) and form a diploid zygote
  3. The zygote develops into a multicellular diploid sporophyte through the mitotic division
  4. The sporophyte undergoes meiosis to produce haploid spores
These haploid spores then develop into new haploid organisms without the fusing of another cell. Finally, he spores undergo mitotic division to produce a new multicellular gametophyte, thus renewing the cycle.\



Bryophytes have been seen as having life cycles that are dominated by the haploid gametophyte, something much, unlike vascular plants. They are usually too thin to support a tall plant so they create ground-hugging carpets that can transport water and nutrients far more easily than a vascular plant that needs to compete with gravity (absence of vascular tissue helps with this too). The opposite of this is seen in extant vascular plants with the sporophyte generations being the more complex formin the alternation of generations process.

Anyways, hopefully this post helps you understand the difference between gymnosperms, angiosperms and why the overall Plant lineage was divided into two major groups. 

Until next time,

Sol

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