Life Cycle of an angiosperms
Reproduction in angiosperms takes place within the flower.
Inside an anther (male part of a flower) each cell experience meiosis (reduction of chromosomes), producing four haploid spore cells. Haploid is a term used to refer to a cell that contains only a single set of chromosomes and therefore only a single set of genes. Each of these four cells becomes a single pollen grain. The wall of the single pollen grain thickens to protect it from damaged when it comes out of the anther. The pollen grain is the entire male gametophyte. A gametophyte is a haploid or gamete-producing, phase of an organism.
Inside the ovary, it contains ovules, where the female gametophyte develops. A diploid (containing two complete sets of chromosomes, one from each parent) cell undergoes meiosis (reduction of chromosomes) to make four haploid (cell that contains a single set of chromosomes) cells. Only one haploid survives, the others disintegrate. This haploid cell goes through mitosis (part of eukaryotic cell division during which the cell nucleus divides) producing eight nuclei. The membrane surrounding these eight nuclei and these eight nuclei are called an embryo sac. The embryo sac is the female gametophyte of an angiosperm.
Inside an anther (male part of a flower) each cell experience meiosis (reduction of chromosomes), producing four haploid spore cells. Haploid is a term used to refer to a cell that contains only a single set of chromosomes and therefore only a single set of genes. Each of these four cells becomes a single pollen grain. The wall of the single pollen grain thickens to protect it from damaged when it comes out of the anther. The pollen grain is the entire male gametophyte. A gametophyte is a haploid or gamete-producing, phase of an organism.
Inside the ovary, it contains ovules, where the female gametophyte develops. A diploid (containing two complete sets of chromosomes, one from each parent) cell undergoes meiosis (reduction of chromosomes) to make four haploid (cell that contains a single set of chromosomes) cells. Only one haploid survives, the others disintegrate. This haploid cell goes through mitosis (part of eukaryotic cell division during which the cell nucleus divides) producing eight nuclei. The membrane surrounding these eight nuclei and these eight nuclei are called an embryo sac. The embryo sac is the female gametophyte of an angiosperm.
Pollination
It is the transfer of pollen from the male reproductive structure to the female reproductive structure.
After the gametophyte has developed inside the flower, pollination will happen next. Some angiosperms are wind pollinated, but most angiosperms are pollinated by animals. Animals such as insects, birds and bats transfer pollen from one flower to another. Flowering plants have bright colors and sweet nectar to attract animals or pollinators. These animals are beneficial because the flowers provide a source of food (pollen and nectar) and the angiosperm also benefits because they carry the pollen from one flower to another, helping them to reproduce. This shows a mutualism relationship because both organisms benefit.
After the gametophyte has developed inside the flower, pollination will happen next. Some angiosperms are wind pollinated, but most angiosperms are pollinated by animals. Animals such as insects, birds and bats transfer pollen from one flower to another. Flowering plants have bright colors and sweet nectar to attract animals or pollinators. These animals are beneficial because the flowers provide a source of food (pollen and nectar) and the angiosperm also benefits because they carry the pollen from one flower to another, helping them to reproduce. This shows a mutualism relationship because both organisms benefit.
Fertilization in Angiosperms
Once a pollen grain lands on the stigma of a flower from the same species, the tube cell creates a tube down through the style to the ovule. The generative cell generates two sperm cells that travel down the tube. Then a double fertilization will take place: one sperm fuses with the egg to make the zygote. The other sperm fuses with two polar nuclei to form a triploid cell. This cell will grow into a food rich tissue called endosperm.
After fertilization occurs, nutrients flow into the flower tissue allowing and supporting the development of the embryo within the seed. As angiosperms seeds mature, the ovary walls thicken making a fruit that encloses the seed. The fruit protects the seed and help the plant disperse its seeds by allowing animals to eat the fruits and the seeds. When the animal eats the seed, the seed is unharmed because it has a tough coat that protects it from the animals' digestive chemicals. Then the seeds sprout in the feces eliminated from the animal. This helps the plant disperse its seeds to areas where there is less competition. The fruits also provide nutrients for the animal.
After fertilization occurs, nutrients flow into the flower tissue allowing and supporting the development of the embryo within the seed. As angiosperms seeds mature, the ovary walls thicken making a fruit that encloses the seed. The fruit protects the seed and help the plant disperse its seeds by allowing animals to eat the fruits and the seeds. When the animal eats the seed, the seed is unharmed because it has a tough coat that protects it from the animals' digestive chemicals. Then the seeds sprout in the feces eliminated from the animal. This helps the plant disperse its seeds to areas where there is less competition. The fruits also provide nutrients for the animal.