seed consists of?
embryo and nutrients surrounded by a protective coat
4 things that all seeds have in common
1.) Reduced gametophytes 2.) Heterospory ( Micro & Megaspores) 3.) Ovules 4.) Pollen
Gymnosperms consist of?
Coniferophyta, Cycadophyta, Gnetophyta (neat tie leaf), Gingkophyta
3 life cycle of Gynosperm
Dominance of the sporophyte generation,
Development of seeds from fertilized ovules,
The transfer of sperm to ovules by pollen,
Advantage of the seed
-They may remain dormant for days to years, until conditions are favorable for germination
-They may be transported long distances by wind or animals
First 4 steps of Gymnosperm Reproduction
1. Most species produce both pollen cones and ovulate cones.
2. A pollen cone contains hundreds of microsporangia held on small sporophylls.
Cells in the microsporangia undergo meiosis to form haploid microspores that develop into pollen grains.
3. An ovulate cone consists of many scales, each with two ovules.
4. During pollination, windblown pollen falls on the ovulate cone and is drawn into the ovule through the micropyle
Last 4 steps of Gymnosperm Reproduction
5. The megaspore mother cell undergoes meiosis to produce four haploid cells, one of which will develop into a megaspore.
6. Two or three archegonia, each with an egg, then develop within the gametophyte.
7. At the same time that the eggs are ready, two sperm cells have developed in the pollen tube which has reached the female gametophyte.
8. The pine embryo, the new sporophyte, has a rudimentary root and several embryonic leaves.
4 Traits of the Coniferophyta
-600 species of conifers
-dominate vast forested regions in the Northern Hemisphere
-Provide lumber and paper
5 Traits of Angiosperm
-Fruits and Flower
-Most diverse and geographically widespread
-Belongs in phylum Anthophyta
-insects and other animals transfer pollen from one flower to female sex organs of another.
-species that occur in dense populations rely on wind for pollination
the male reproductive organs, produce microspores that will give rise to gametophytes.
-Pollen produce in the filament and anther.
female megaspores and their products, female gametophytes. At the tip of the carpal is a sticky stigma that receives pollen. A style leads to the ovary at the base of the carpal.
-heterosporous, producing microspores that form male gametophytes and megaspores that form female gametophytes.