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Chapter 26- Seed plants - Coggle Diagram
Chapter 26- Seed plants
1.) Evolution of seed plants
Introduction
almost all of food and beverage comes from seed plants! (approx. 80% of calories)
wood products, fuel, fiber for clothing, rope
secondary compounds
drugs and medicine, perfumes, latex rubber
approx 25% of prescription drugs contain an active ingredient from plants
Evolution history
seed plants are the angio and gymno sperms
the seed plants first appeared 305-465 MYA
the angio (flowering) were the last plants to show up
Evolutionary adaptation of seed plants to Dry Land
embryo
- produced form diploid zygote, grows into the sporophyte when germinates
seed
- a protective mechinism and a way for the seeds to disperse
male gametophyte
: within pollen grains (contain the sperm)
protected from decciation
no dependent on h2o to reach the female organs
female gametophyte
: develop within an ovule (contain egg and endosperm, which helps support growth of the embryo)
enclosed within diploid sporophyte tissue in angiosperms
Reproductive adaptations of seed plants:
reduced & retained games.
seed plants are hetero sporous
megaspores (grow in female games)
microspores (grow in males)
both games mature within the sporangia = more protections
Seed: develops from fertilized ovule
ovule: integument + megasporangium + megaspore
embryo, food supply, and seed coat
megaspores germinate within the ovule, devlops into tiny ffemale game., produces eggs which will eventually be fertilized
Pollen Grains: male game. surrounded by pollen wall (partly secreted by sporophytes)
pollination: transfer of a pollen to a part of the seed plant that contains the ovule
Major groups of seed plants
gymnosperms
plants with "naked seeds"
ALL have ovule exposed on a scale
ALL lack flowers & fruits of the angio sperm
vascular system (tracheids)
dom. sporophtes
ALL are heterosporous
male and female reproductive organs can form in cones or strobilli
can be Mono or Diecious
A CONIFER
angiosperms
1.) Flower- structure specialized to facilitate sexual reproduction
2.) Fruit- mature ovary of the flower, thicker around seeds
may include additional tissue
may be fleshy or dry
main func. is enhancing seed dispersal
success mainly due to coevolution with pollinators
look at image and label parts of the flower
Monocots
one cotyledon
veins usually parallel
vascular tissue scattered
root system is fibrous (no main)
pollen grain with one opening
floral orangs usually in multiples of 3
Eudicot
two cotyledons
veins usually netlike
vascular tizzue arranged in ring
Taproot (main root) usually present
pollen grain with three openings
floral organs usually in multiples of 4 or 5
Gymnosperms:
1.) Confier
most diverse today
"cone beares"
male pollen cone (sperm not motile)
female ovulate cone
2.) Cycads
fern-like or palm-like fronds that radiate from the centrall stem
Flagellated sperm
3.) Ginkgophyta
flagellated sperm
one extant tree: ginkgo biloba
herbal medicine
4.) Gnetophyta
3 distinct genera
1.) Ephedra (desert, plains?)
2.) Gnetum (in tropics)
3.) Welcitschia (in desert)
Angiosperms: know the life cycle
microsporangia
male sporocytes (2n)
meiosis
Microspores (n)
mitosis
pollen grains
I generative cell
1 tube cell
Double fertilization w 2 sperm nuclei
one fuzes with eqq, forming zygote (2n)
the other fuzes with 2
central nuclei (polar nuclei), forming endosperm (3n
) food supply in seed
Ovuole
megasporangium
megasporocyte (2n)
meiosis
4 megaspores (n)only large megaspores survives
mitosis x3
8 nuclei distributed among 7 cells of female gametophyte
3 cells at one pole become eqq and 2 synergids (remaining 3 cells become antipodal cells)