UNIT 2: KINGDOM PLANTAE 2 (26) Flashcards
1
Q
Evolution of seed plants:
A
- The First seed plants were the progymnosperms
- Pro = before (before gymnosperms)
- Similar to cone producing plants
- Sporophyte grow from seeds but it grew spores familiar to modern ferns
2
Q
Seed plants evolution cycle:
A
- Inherited the haplodiplontic life cycle of ancestors
- Sporophyte (2n) makes spores (n) that form gametophyte
- Gametophyte (n) makes gametes (n)
- Gametes (2n) fuse into a zygote (2n) and grow into sporophyte
3
Q
Evolution of seed plants changes:
A
- Sporophyte is the dominant generation, and cache large and long lived
- Gametophyte is reduced to several cells and is heterosporous (produce 2 different kind of spores)
- Produce different male and female gametophytes
4
Q
Modern seed plants traits:
A
- Modern seed plants have traits to help them live in dry habitats
- Seeds have layers of tissue to prevent drying
- Can be in a state of dormancy for years
- No more swimming sperm
5
Q
Pollen
A
- = male gametophyte
- Pollen grains carry sperm within
- Dispersed by wind or a pollinator
- Produce a pollen tube
6
Q
Female Gametophytes
A
- Lives within sporophyte
- Contains the egg
- Enclosed within the sporophyte ovule
- Receives the pollen
7
Q
Gymnosperms
A
- Seed-producing plants, but unlike angiosperms, they produce seeds without fruits
- 319 MYA
- Dominant plant for 200 million years
8
Q
Angiosperms
A
- Angiosperms are plants that produce flowers and bear their seeds in fruits
Surpassed gymnosperms by 100 MYA - Most abundant and biologically diverse plant group in most terrestrial biomes
9
Q
Gymnosperms Reproductive Methods:
A
- May be monoecious (one home) or dioecious (two homes)
- Both male and female gametophytes on same or different plants respectively
10
Q
Gymnosperm Reproduction:
A
1) Pollen lands on strobilus
2) Forms pollen tube from specialized tube nucleus to ovule
3) Two sperm nuclei ove through tube, and one fertilizes the egg
4) Results in sporophyte embryo later housed in seed
11
Q
Division Coniferophyta:
A
- Conifer = cone bearing
- Phuton = plant
- Adapted to cold and dry climates
- Evergreen, thick cuticle
- Leaves as needed or scales
- Resist desiccation
- Wind pollinated
- Strobilus is typical cone
- Pines, sources, firs, cedars, sequoias, and yews
- Hard plants and grow where other plants don’t
- Better for hot dry environment or cold dry environment
- Biggest trees on earth
- Oldest living tree is the Bristlecone Pine (Pinus longaeva)
12
Q
Division Cycadophyta:
A
- Cycad = Egyptian palm
- Phuton = plant
- Mild climates have palm tree like stems and leaves
- Strobilus is large cone-like structures (dioecious)
- Pollinated by beetles
- Few species exist
- Face possible extinction, several species are protected
-Often used as ornamental plants
13
Q
Division Ginkgophyta:
A
- 銀杏 = silver apricot
- Phuton = plant
- 1 living representative - Ginkgo biloba
- Fan-shaped leaves
- Dioecious
- Femalte: large seed with fleshy coating
- Male: small: strobilus for pollen
- Deciduous
14
Q
Division Gnetophyta:
A
- Phylogenetic position of the gnetophytes is not resolved
- DNA/molecular analysis places the closer to conifers
- Large xylem vessels like angiosperms
- 3 genera, 65 species
- Welwitschia - Africa
- Ephedra - North America (“Mormon tea”)
- Gnetum - Global, variety of shrubs and vines
15
Q
Angiosperms:
A
- Angio = ancased
- Sperm = seed
- > 300,000 species
- Represent 80% of all living plants
- Second only to insects in terms of diversification
- Flowering reproductive structure
- Fruit covering seed
- Oldest angiosperm is Archaefructus (125 MYA)
- Has male and female structures in the “flowers”
- No petals or sepals
- Has pod-like fruit with seeds
- Amborella is the most “primitive” modern angiosperm
- Has a simple flower which is mostly leaf-like
