<span>Light dependent reactions require an actual source of light, and this is from the sun, for energy to carry out the first stage of photosynthesis. They need solar energy to split a water molecule in order to obtain electrons from hydrogen to be used in fueling photosynthesis. Light independent reactions do not require a light source for energy but rather they use energy that was created by the light dependent reactions to complete the process of photosynthesis in which different carbohydrates for the plant are made.</span>
Two factors contributed to the success of the pteridophytes: the extreme miniaturization of the gametophytic generation and an important development of the sporophytic generation (development of the tree forms).
Pteridophytes are a group of plants that peaked in the Carboniferous (-300 million years). It is the first great terrestrial plant civilization. These plants would have appeared in the Devonian -400 million years ago, perhaps from certain primitive terrestrial plants which, unlike bryophytes, would have favored the diploid generation on the haploid generation.
Particularly well adapted to terrestrial life, they have created, thanks to the development of tree forms, immense forests whose fossilization is at the origin of coal deposits.
Pteridophytes are at the origin of an evolutionary lineage based on the extreme miniaturization of gametophytic generation and an important development of sporophytic generation, leading to all tracheophytes including current flowering plants. Pteridophytes are well adapted to terrestrial life, however fertilization still requires the presence of water since male gametes are swimmers.
<span>Estrogen is involved in a feedback mechanism associated with the follicular phase of menstruation. </span>