As we reduce the role of the gametophyte, we reduce the dependency on _______.
What are microspores?
Spores that give rise to male gametophytes
What are megaspores?
Spores that give rise to female gametophytes
What 4 features are common to all seed plants?
1. Reduced gametophytes
What is a gymnosperm?
A vascular plant in which the seeds are not enclosed by a protective fruit or flower
What is the evolutionary advantage of seeds?
- They are multicellular
- Have a protective seed coat and their own food supply
- Allows them to be protected and remain dormant for years, whereas spores have a shorter lifetime.
List the phylum of gymnosperms
What are the characteristics of the Phylum Cycadophyta?
- Look like palms but aren't
- Large cones
- Tall unbranched trunks
- Crown of pinnately divided leaves
- Flagellated Sperm
- Thrived during Mesozoic era
What are the characteristics of the Phylum Gingkophyta?
- Fan shaped leaves
- Flagellated sperm
- Hair like veins branch dichotomously (one branches into two)
- Deciduous (sheds annually)
- Dioecious (m/f reproductive parts on separate trees)
Only one species remaining - Gingko biloba
Which gymnosperm has a seed coat with a nauseating odor?
What are the characteristics of the Phylum Gnetophyta?
- leaves look similar to leaves on flower stems
- seeds look like fruits but aren't
- drought tolerant shrub
- cluster of ovulate cones
- plant only produces two massive leaves
- strobili in the center
- can live for thousands of years
What are the characteristics of the Phylum Coniferophyta?
- largest of the gymnosperms
- big trees, most are evergreens
- do photosynthesis all year round
- don't shed their leaves
What phylum does the giant sequoia belong to?
Who's the oldest tree?
What are 3 key features of the gymnosperm life cycle?
- dominance of the sporophyte generation
- development of seeds from fertilized ovules
- transfer of sperm to ovules by pollen
Explain the life cycle of a pine (gymnosperms)
1. Conifer species have ovulate cones and pollen cones
2. Microspores develop into pollen grains from the pollen cones and enter the integument of the ovule
3. Meiosis occurs and female gametophyte develops
4. Sperm fertilizes the egg (2n)
5. The seed will grow and produce a sporophyte which develops into a tree
Explain how a gymnosperm's egg is fertilized.
1. The ovule of a cone consists of a fleshy megasporangium (which holds a megaspore) and is surrounded by a protective layer called an integument
2. There is an opening in the integument called a micropyle where a pollen grain enters
3. While the megaspore is developing, 4 haploid cells are produced and 1 survives.
4. The megaspore develops into a female gametophyte that contains eggs
5. The pollen grain (containing a male gametophyte) extends a tube to the female gametophyte, releasing its sperm to fertilize it.
6. The fertilized egg now develops into a seed. The megasporangium dries out and collapses and in replace there is a food supply that surrounds the seed. A spore wall surrounds the food supply and a seed coat (originally the integument) surrounds everything.
What is an angiosperm?
A flowering, vascular plant in which the seeds are enclosed by a protective fruit or flower
What is the phylum of angiosperms?
Magnoliophyta (aka Anthophyta)
List the structures of a flower Include picture, slide 19
What is the stamen?
The male reproductive structure of a flower, containing the filament and the anther (where pollen is produced).
- produces microspores that develop into pollen grains containing male gametophytes
What is the carpel?
The female reproductive structure of a flower, containing the ovary (has ovules), the style (stem), and the stigma (sticky and received pollen).
- produces megaspores that contain female gametophytes
What is pollination?
The act of transferring pollen grains from the male anther of a flower to the female stigma
What is the function of the sepal?
Protect the ovary and prevent insects from getting to the nectar
What is the function of the petal?
What is the name for all the sepals on one flower?
What is the name for all petals on one flower?
What is a perianth?
Calyx (sepals) + Corolla (petals)
What is a fruit?
Seed-bearing structure in angiosperms formed from the ovary after flowering
What is the anatomy of a fruit?
1. Exocarp - skin
2. Endocarp - Inner boundary around the seed
3. Mesocarp - tissue b/w exocarp and endocarp