The primary wall is made up of __. Plants now have a secondary wall composed of __, the first vascular tissue that provided structural support. The secondary cell wall ends contain __
cellulose; lignin; pits
may have orignated as small stem outgrowths supported by single, unbranched strands of vascular tissue (needle-like projections)
branched vascular systems, may have evolved by the fusion of branched stems
Seeds allow for __
- stored moisture
- allowed humans to go from nomadic to settling in one location
- reduced gametophyte (becomes microscopic)
- ovules & pollen
- consists of the megasporangium that makes the megaspore
male gametophyte that goes to the megasporangium: pollination
Pollen tube seeks out the egg. Then fertilization occurs.
3 generations in one seed
- seed coat from integument (2n): 1st generation
- female gametophyte tissue, food supply for embryo (n): 2nd generation
- embryo, new sporophyte (2n): 3rd generation
The new sporophyte will grow and consume the megasporangium.
She calls them "grandmother, mother, granddaughter."
- not enclosed in an ovary "naked seed"
- Seeds sits on modified leaves of the cones
examples of oldest gymnosperms: cycads & ginkos (only 1 extant species: ginko biloba)
type of gymnosperm, short plants with large leaves.
3 genera: gnetum, wetwritschia, ephedra
most diverse gymnosperms
large trees: pine, sequoia, yew, juniper, fir
- extinct, has some features of gymnosperms such as heterospory and vascular tissue that leads to wood structure
- no seeds
special characteristic of gymnosperm life cycle
temporal separation of megasporangia (ovulate cone) and microsprorangia (pollen cone)
In gymnosperms, microsporangium produces microsporocytes that release __
- pollen grains (containing male gametophytes) to the megasporangium (female)
protect the developing bud
modified leaves that attract pollinators
male parts of the angiosperm
2 parts: anther & filament
female parts of the angiosperm
Multiple carpels are called pistils.
3 parts: stigma (where pollen sticks), style (pollen goes down pollen tube), ovary (holds ovules)
angiosperm structures (figure)
type of ovary that disperses seeds
fruit "skin" acting as walls of the ovary that surround the seed
ancestors of angiosperms that still has carpels, stamens, seeds, but doesn't have sepals or petals
angiosperm monocot vs eudicot
monocot: 1 cotyledon (embryonic leaves), parallel veins, scattered vascular tissue, fibrous roots, pollen grain with one opening, floral organs usually in multiples of 3
eudicot: 2 cotyledons, netlike veins, ring-arranged vascular tissue, tap roots, pollen grain with 3 openings, floral organs usually in multiples of 4 or 5