Plants Flashcards
what do plants produce
*Food
*Natural Products (O2, ozone, coal, oil, gas, wood, paper, medicine, limestone etc.)
*Ecosystem services (ex. protection from erosions or environmental disasters)
what two influential scientific inquiries were made using plant models?
Genetics: Mendel pea plants
Transposons: McClintock corn plants
when did aquatic plants invade land
475 million years ago (Ma)
what made it difficult for aquatic plants to go on land
*cells drying out
*physical support on land (air less dense than water)
* harder for sperm to swim-> sexual fertilization/ reproduction
land advantage over water for plants
less competition for light on land
green algae and land plant shared traits
- cellulose cell wall
- chlorophyl a and b
-sperm with 2 anterior (front) flagella
*shared common ancestor
preadaptations
trait already present that allowed for major ecological transition
*aquatic plants to land plants
preadaptations of chlorophytes
- fresh water habitat; live on edges of pond so as water level fluxuates -> half aquatic and half land
-life cycle that allows dispersal by wind using spores
zygotic meiosis
Life cycle of Chlorophylls: multicellular algae (haploid) produces diploid zygote which undergoes meiosis and produces 4 haploid spores
sporopollenin
(most stable) biopolymer that covers spores; uv protectant, dehydration resistant, decay resistant
how did first land plants get nutrients with no soil
associated with mycorrhizal fungi to help get nutrients from the bedrock
4 main adaptations of land plants
cuticle, pores, stomata, embryo
cuticle
upper layer on plants that reduces water loss and gas exchange
Pores
hole in cuticle to help with gas exchange; water loss
Stomata
mechanism that helps pores open and close to control gas and water exchange based on environment/needs
Embryo
young sporophyte that is nourished by maternal tissue
Gametophyte
-haploid
-makes gametes by mitosis
Sporophyte
- diploid
-makes spores (haploid) by meiosis
Bryophytes
-includes liverworts, mosses and hornworts
-live in moist understories of forest
-very short (no vascular system)
-gametophytes are dominant life stage
Liverworts
-pores (NO STOMATA)
-look like earlies land plants
Mosses
-have stomata
-economically important for florist trade and making Peat (fuel and alcohol flavoring)
Hornwart
long living
Where are the sporophytes on Bryophytes
saprophytes stem up from the gametophyte base and perform meiosis to make spores
why did plants get taller/ develop vascular systems
to be taller than competitors
vascular system transfers
water from root -> leaves
sugars from leaves -> root and stems
do saprophytes, gametophytes or both have vascular systems?
ONLY sporophytes evolved vascular systems; sporophyte dominance
Ferns
-dominant life stage: sporophytes (diploid)
-gametophyte and sporophyte grow independently; do their own photosynthesis
what are ferns categorization
seedless vascular plants
vascular plants with seeds
gymnosperms and angiosperms
4 divisions of gymnosperms
ginkgoinae, cycads, gnetidae, conifers
Gymnosperms: ginkgoinae
stinky coding on seeds
Gymnosperms: cycads
-look like palm tree
-very endangered due to climate
Cycad conservation efforts
use oxygen isotope that i geographically distinct to see if tree is native to area or was poached and bought
Gymnosperms: Gnetidae
-only grows 2 leaves from middle stem
- leaves fray as plant grows old
Gymnosperms: Carnifers/ pinidae
- pine and fur trees
-largest by volume plant
Angiosperms
-most diverse and successful group of land plants
-produce fruit and flowers
-double fertilization
-seeds enclosed in sporophyll
sporophyll
leaf modified for reproduction
ex. flower petals are leaves that evolved for reproductive function
types of seed plants
gymnosperms and angiosperms
order of trait evolution for land plants
- alternating generation (gametophyte and sporophyte)
- stomata
- long lived sporophyte (dominant life form)
- vascular system
- seeds
- flowers
evolution of land plants: dominant life stage
started with gametophytes as dominant life stage (bryophytes) -> gametophytes and sporophytes being independent (ferns and seedless land plants) -> dominant sporophyte (seed plants)
how do seed plants reproduce
Spores are NOT DISPERSED; spores held onto by female gametophyte and fertilized by male gametophyte (pollen grain)
pollination
male gametophyte moves to female gametophyte -> fertilization
gymnosperm seeds
naked seed (no sporophyll coding); pollen delivers directly to ovule
ovule
structure of sporophyte in which female gametophyte + egg develops
angiosperm seed
hidden seed; ovule encased in sporophyll called carpal where pollen is delivered to
why are seeds more beneficial than spores
- can remain dormant and disperse when favorable by environmental conditions
-build in food for seeds in embryo
-targeted dispersal by animals; not just dispersed by wind
-invest more in fertilized ovules -> more resources for next generation of sporophytes
spores in seed plants
spores are not dispersed and become gametophytes while still on sporophyte
what are fruits
structures derived from carpal tissues; derived from ovary that encloses seeds
*only in angiosperms
what is the female gametophyte called
pistil
(includes ovary + style + stigma/landing pad for pollon)
pistil structure
*8 nuclei; 7 cells
*large center cell with 2 polar nuclei
what is the male gametophyte called
stamen
male gametophyte structure
anther (sporophyte where pollen grains produced) held out by fillimants
what does a spore turn into
a gametophyte through mitosis
what does an egg turn into
a zygote by fertlization
what does an ovule turn into
a seed by fertilization
what do ovaries/ carpal tissue turn into
fruit through fertilization
Pollination
mechanism that promotes transfer of pollen from antlers to the stigma; animals and wind pollinate