The process of double fertilization is an integral one to all of the flowering plants on Earth. Double fertilization is a process by which two sperm sells are transported by pollen to the ovaries of an angiosperm. One sperm fertilizes the egg to form a zygote. The other sperm fuses with a polar nuclei to form a tripolar endosperm nucleus. The endosperm is responsible for providing nutrients to the developing zygote and allows the seed to undergo the initial stages of germination when specific conditions are met.
The evolution of the double fertilization process is interesting because it involves a gene that inhibits the expression of another gene. Originally, a specific gene would limit the amount of sperm cells in any given pollen to one. However, by inhibiting this gene, angiosperms are able to produce two sperm cells in a pollen. This mechanism allows the process of double fertilization to occur and is a defining characteristic of all flower plants on Earth today.
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