evolution of plants Flashcards
what was the first direct evidence of a plant
- cooksonia
- no leaves, roots, or flowers
had vascular tissue to conduct water
liberating spores
advantages of plants living above water line
- brighter sunlight
- more CO2 in air
- abundance of nutrients on shoreline
disadvantages of plants living above water line
- dry environment
- strong affect of gravity
- no nutrients in atmosphere
- rapid changes in temp
what is the apical meristem
region of stem cell division at tip of roots and shoots
what does the cuticle do
protects against desiccation
what are bryophytes
paraphyletic group of non-vasular plants
–> don’t produce seeds or flowers
what is the life cycle of a bryophytes like
-dominated by gametophytes
- no vascular system (stem/rods)
- spore germination and sperm cell swimming depends on water
what are rhizoids
filament that attaches to substrate
what is vascularization
presence of lignified tissues that transport water, nutrients and sugars through plant
what are the 2 transport tissues in plants
xylem (water, minerals to leaves), phloem (sugars)
where are spores produced
leaves
homosporous vs heterosporous
homosporous: 1 type producing bisexual gametophyte
–> most seedless vascular plants
heterosporous: 2 types producing male or female gametophyte
–> all seed plants
what are the advantages of heterospory
specific functions for each sport
seperate female gametophyte can better nourish embryo
–> no energy spent producing male gametes
higher genetic diversity
what are spermatophytes
seed plants
what are the 5 key innovations of seed plants
1) extremely reduced gametophyte is protected from environmental stresses
2) ovule: structure containing megasport
–> fertilization without water
3) heterosporous
–> microspore: male gametophyte, can disperse farther
–> megaspore: female gametophyte, nourishes embryo
4) pollen grain: male gametophyte enclosed in pollen wall
–> can disperse far
5) production of seed
–> increases survival of plants
what are angiosperms
flowering plants (produce seeds)
seed enclosed in a chamber that matures into a fruit
what is a gymnosperm
seed plants, but no flowers
seed is exposed on spotophylls
–> evolved as climate became dry
what is a fruit
mature ovary of flower that helps with seed dispersal
what is a flower
modified leaves (sporophylls) specialized in reproduction
carpel (megasporophyll) produces female gametophyte
stamen (microsporophyll): produces male gametophyte
what is double fertilization
(flower plants)
- one sperm cell fertilizes egg (zygote)
- other sperm cell fuses will 2 nuclei of central cell (endosperm)
–> ovary matures into a fruit
–> ovules mature into seeds
what is cross pollination
process of applying pollen from one flower to the pistils of another flower
