Evolution of land plants Flashcards
why are land plants important?
almost all life on earth is land plants
fundamentally changed the environment on earth
primary producers in terrestrial food web
domestication and cultivation of plants
what is the origin of land plants?
land plants started to grow on beaches to have access to large amount of water
can get nutrients from the water
downside can’t get enough sun light to photosynthesize
what is the common ancestor of land plants
likely charophytes (green algae, stonewort)
what kind of group are Charophyta?
paraphyletic group
what is paraphyletic group?
a group that doesn’t have all of its decedents
what is a monophyletic group?
a group that has all of its decedents
Why was dryness a challenge?
had no control over water content and were restricted to moist areas
water was essential for reproduction
what was the first adaptation to fight dryness?
the cuticle
evolved early on but still had some water loss
present in all bryophytes
what was the problem with the cuticle?
prevented carbon dioxide to be taken up
solution was pores
what was the second adaptation to fight dryness?
stomata
present in moss and hornworts
prevented water loss and opened when carbon dioxide is needed
selectively and actively open and close
what are characteristics of bryophytes?
no vascular tissues
no roots
gametophyte (haploid) phase dominant
what is the challenge with competition for light and gravity?
grow upwards to get more light for photosynthesis
competition for light, lead to selection for growth and leaves to increase photosynthetic ability
what is the solution for competition for light and gravity?
lignin
makes secondary cell wall stronger and more strong and rigid
water proof barrier
resistant to decay and attack by microbes
what are microphylls?
single unbranched strand of vascular
lycophytes
- club mosses and scale trees
what is a megaphyll?
multiple, branched strands of vascular tissues
evolved at least twice independently
pterophytes
- ferns, horsetails and whisk ferns
what’s the challenge pf spatial segregation and transportation of resources
minerals and most water is in the soil
light and carbon dioxide for photosynthesis above ground
where does primary growth happen?
the apical meristems at the root and shoot tips
what do roots and shoots provide?
they provide support for the plant and transportation of minerals, water and organic substances
what is mineral transportation?
short distances between cells
long distances between roots and shoot parts (xylem and phloem)
what is phloem?
vascular tissue which conducts sugars though the plant body
what is xylem?
vascular tissue which conducts water and dissolve minerals from soil to roots to shoots
what are mycorrhizia?
good at extracting nutrients from the soil and give to the plants
plants will give them sugars in return
what are hydroids?
like vascular system but for moss
independently evolved (convergent evolution)
functions the same and xylem and phloem
what are most seedless vascular plants?
homosporous
some are heterosporous
what is homosporous?
plants produce 1 type of spore and will develop in to one type of gametophytes
what is a gametophyte?
they are bisexual
can be both egg and sperm
what is a heterosporous?
plants produce 2 types of spores which develop into 2 types of gametophytes
what is endosporous development?
in many heterosporous plants, gametophytes produced by spores develop inside spore wall
provides protection for gametes and later for developing embryo
what is the problem with aridity and reproduction?
gametophytes of bryophytes, some gymnosperms produce haploid sperm cells
impossible for sperm to reach egg in absence of water
what’s a gymnosperm?
“naked” seed plants
pollen grains produced nonmotile sperm
what is pollenation?
transfer of pollen to female reproductive parts
what is the ovule?
sporophyte structure that produces the female gametophyte with egg
connected to sporophyte by protective tissue
what are seeds?
structures from when ovule matures after fertilization through pollination (diploid)
surrounded by nutritive tissues
they have major adaptations for uncertain environments
what are angiosperms?
flowering plants with covered seeds
have carpels at center that protects ovule and seeds
fruit nourishes and disperses sends
double fertilization
what are monocots?
grasses, palms
parallel-veined leaves common
bundles of vascular tissue scattered in stem
what are eudicots?
most fruit trees
net-vined leaves common
central core of vascular tissue in stem
what are some angiosperm adaptations?
efficient transport
many have specific pollinators instead of just air currents
