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.
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Answer:12.
Containing two complete sets of chromosomes, one from each parent.
Explanation: Once mitosis is complete, the cell has two groups of 46 chromosomes, each enclosed with their own nuclear membrane. The cell then splits in two by a process called cytokinesis, creating two clones of the original cell, each with 46 monovalent chromosomes.
Photorespiration limits casualty products of light reactions
that build up in the absence of the Calvin cycle. In many plants,
photorespiration is a problem because on a hot, dry day it can drain as much as
50% of the carbon fixed by the Calvin cycle. The closing of stomata reduces access to CO2
and causes O2 to build up. These conditions favor a seemingly not useful process
called photorespiration. In most plants
(C3 plants), initial fixation of CO2, via rubisco, forms a three-carbon
compound. In photorespiration, rubisco
adds O2 instead of CO2 in the Calvin cycle. Photorespiration eats up O2 and
organic fuel and releases CO2 without producing ATP or sugar. Photorespiration
can evolve relic because rubisco first evolved at a time when the atmosphere
had far less O2 and more CO2.
