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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
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microphyl
may have orignated as small stem outgrowths supported by single, unbranched strands of vascular tissue (needle-like projections)
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megaphyl
branched vascular systems, may have evolved by the fusion of branched stems
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Seeds allow for __
- stored moisture
- allowed humans to go from nomadic to settling in one location
- reduced gametophyte (becomes microscopic)
- heterospory
- ovules & pollen
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ovule
- consists of the megasporangium that makes the megaspore
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pollen
male gametophyte that goes to the megasporangium: pollination
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germination
Pollen tube seeks out the egg. Then fertilization occurs.
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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."
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gymnosperms
- 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)
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gnetophyta
type of gymnosperm, short plants with large leaves.
3 genera: gnetum, wetwritschia, ephedra
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coniferophyta
most diverse gymnosperms
large trees: pine, sequoia, yew, juniper, fir
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progymnosperm
- extinct, has some features of gymnosperms such as heterospory and vascular tissue that leads to wood structure
- no seeds
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special characteristic of gymnosperm life cycle
temporal separation of megasporangia (ovulate cone) and microsprorangia (pollen cone)
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In gymnosperms, microsporangium produces microsporocytes that release __
- pollen grains (containing male gametophytes) to the megasporangium (female)
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sepals
protect the developing bud
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petals
modified leaves that attract pollinators
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stamen
male parts of the angiosperm
2 parts: anther & filament
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carpel
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)
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angiosperm structures (figure)
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fruit
type of ovary that disperses seeds
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pericarp
fruit "skin" acting as walls of the ovary that surround the seed
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proto-angiosperm
ancestors of angiosperms that still has carpels, stamens, seeds, but doesn't have sepals or petals
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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
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