Slide 1
The angiosperm life cycle is similar to the gymnosperm life cycle in that it shows complete reduction of the gametophyte and the female gametophyte remains enclosed within sporophyte tissue.
Where gymosperms have cones - angiosperms
have flowers.
The anther produces pollen while the female ovules contain an egg cell.
When the pollen lands on the stigma - fertilization can take place to produce the zygote which then grows into the embryo.
The embryo is housed within a seed and the seed is housed within fruit derived from the ovary.
The seeds are released from the parent plant and can
then germinate to produce a new individual.
Slide 2
The process of fertilization in the angiosperms is known as double fertilization.
The pollen grain contains two haploid sperm nuclei
The megaspore - the female gametophyte - contains nne haploid egg nucleus and two haploid polar nuclei.
When fertilization takes place, one sperm fertilizes the egg to produce the diploid embryo.
The other sperm combines with the 2 polar nuclei to produce the triploid endosperm - this endosperm nourishes the embryo until it germinates and can begin to photosynthesize.
Slide 3
The angiosperms are divided into two groups depending on the type of seed produced.
The monocots include plants like corn and the other grasses. The monocots have a single embryonic seed leaf (this seed leaf is known as a cotyledon).
The dicots which include beans and other broadleaf plants have two embryonic seed leafs.
Both types of seed tend to have a significant amount of endosperm so seeds can survive in the environment until conditions are right for germination.