Evolution + Development Flashcards
What is a plant? (PCE)
- Photosynthetic
- Has cell wall
- Eukaryotic
History of Life (GTS)
- boundaries between units in the Geologic Time Scale are marked by dramatic biotic change
- plants are eukaryotes
Time:
Humans appeared on earth around 11:58:43 pm
Land plants appeared on earth around 9:52 pm
The major lineages of plant evolution
Land plants (bryophytes, pteridophytes, gymnosperms, angiosperms)
vascular plants (pteridophytes, gymnosperms, angiosperms)
seed plants (gymnosperms, angiosperms)
Green algae
- closely related to land plants and are believed to be the origin of land plants
- most primitive plants, share characteristics with higher plants and microbes
- diverse habitats: aquatic and non-aquatic
- forms: unicellular, few-celled, filaments, flat sheet parenchytamous
- reproduction: both sexual and asexual
green algae example: Chlamydomonas reinhardtii
- Unicellular (single-celled), green algal model species
- found in diverse conditions
- they are haploid - dominant life form > diploid.
- Used to study photosynthesis, motility,
responses to stimuli such as light, and cell-cell
recognition > apply to more complex plants and
animals.
Land plants: bryophytes
- Simple land plants
- no true roots/leaves, lack vascular system, no structural support
- Have simple structures, such as water conducting cells, cuticles, stomata
- Life cycle: mostly sexual reproduction
moss: Physcomitrella patens
- -> goes through both haploid (gametophyte - 1n) and diploid (sporophyte - 2n) stages
Life cycle of a bryophyte: moss
Gametophytes (haploid, gamete producing) (1n) Sporophytes (diploid, spore producing) (2n)
Sporophytes: diploid, spore producing, smaller, short-lived, some nutritionally dependent on gametophytes
Gametophytes: haploid, gamete producing, larger, long-lived, and photosynthetic
Bryophyte, moss: Physcomitrella patens
- Multicellular organisms alternating between dominant haploid gametophyte and small/short-lived diploid sporophyte
- Important for studies on plant evolution, development, and physiology
- –> No vascular tissue, true roots/stems/leaves, and flowers and seeds.
- –> Has many intact signaling pathways found in angiosperms
- Highly efficient homologous recombination > allow genes for replacement and elimination
Pteridophytes
- vascular tissue (shoots, roots, and leaves)
- seedless
- life cycle: mostly sexual reproduction
Life cycle of a seedless vascular plant: fern
mostly sexual reproduction:
plants reproduce using haploid, unicellular spores instead of seeds
- The life cycle of seedless vascular plants is an alternation of generations, where the diploid sporophyte alternates with the haploid gametophyte phase.
Gametophytes (haploid, gamete producing) (1n) Sporophytes (diploid, spore producing) (2n)
Sporophytes: diploid, spore producing, smaller, short-lived, some nutritionally dependent on gametophytes
Gametophytes: haploid, gamete producing, larger, long-lived, and photosynthetic
Fern: Dicksonia Antarctica
– > An evergreen tree fern native to eastern Australia
• Typically grow to about 4.5–5 m (15–16 ft),
• Reproduction primarily from spores,
• Can grow in a variety of conditions (acid, neutral and alkaline, semi-shaded, dry etc)
Gymnosperms
- Vascular tissue (shoots, roots, and leaves)
- Naked seeds (embryo protected in seeds)
- Life cycle: mostly sexual reproduction
ex: pine
Life cycle of a gymnosperm: pine
Gametophytes (haploid, gamete producing) (1n) Sporophytes (diploid, spore producing) (2n)
Sporophytes: diploid, spore producing, smaller, short-lived, some nutritionally dependent on gametophytes
Gametophytes: haploid, gamete producing, larger, long-lived, and photosynthetic
Gingko biloba
- medicinal/ food use
- native to China
- fossils dating back 270 million years > living fossil
Angiosperms
- Vascular tissue (shoots, roots, and leaves)
- Protected seeds (making flowers)
- Monocots and dicots
- Life cycle: mostly sexual reproduction