Seed Plants Flashcards
List examples of seed plants.
Conifers
Angiosperms
Ginkgo
Cycads
Define seed.
Embryonic plant encased within a protective coating, typically resourced with stored food.
Why are the four major derived features in seed plants (major events in plant evolution)?
- Development of secondary growth (vascular cambium) provides structural support
- Produce two types of spores (heterospory)
(Megaspores in female ovule which later becomes seed) (microspores in male pollen produced in anthers) - Reproduce by seeds (female gametophyte and embryo enclosed in ovule that grows into seed, nourished and protected by parent plant)
- Male gametes transported in pollen (eliminated the need for water)
What is the vascular cambium?
Meristem that produces additional vascular tissue (xylem and phloem)
Are ferns and mosses homosporous or heterosporous?
Homosporous.
Are seed plants homosporous or heterosporous?
Heterosporous
What is homospory? What plants exhibit this? What does it develop into?
One type of spore produced by the sporophyte.
This spore develops into bisexual gametophyte that is able to produce both eggs and sperm.
E.g some mosses, most ferns
What is heterospory? What plants exhibit this? What does it develop into?
Two different types of spores produced by the sporophyte.
Megasporangium > megaspore > female gametophyte > egg
Microsporangia > microspores > male gametophyte > sperm
Name the process by which seed plants reproduce and describe the steps.
Heterosporous alternation of generations
- Sperm and egg fuse to produce DIPLOID zygote
- Zygote grows into DIPLOID sporophyte
- Sporophyte undergoes meiosis to produce megaspores (female) and microspores (male).
- Megaspores develop into megagametophyte while microspores develop into microgametophyte.
- Microgametophyte develops into sperm, megagametophyte develops into egg.
How are conifers (gymnosperms) pollinated?
Wind pollinated
What is distinctive about pollination and fertilisation for confers?
Separated in time, can be years.
Regarding fertilisation in conifers, what is novel? Compare this to flowering plants (angiosperms).
Integument partially covering ovule. This contrasts flowering plants as angiosperms have an extra ovule wall enclosing the integument, completely protecting the ovule.
Why are cycads considered primitive?
Because they still have motile flagellate sperm cells but pollinate via wind.
What countries were in Gondwana?
South America Australia Africa Antarctica India
What plant dominates terrestrial ecosystems?
Angiosperms
