colonization of land Flashcards
Definition of plants
no strong definition yet, many disagreements
4 major groups of land plants
1.mosses (belong to bryophytes)
2.ferns (seedless vascular plants)
3.gymnosperms (seeded vascualr-seeds onn leaves)
4. angiosperms (seeded vascular-seeds in fruits and flowering)
non-vascular plants
-no vascualr tubes
-usually small and found in damp, moist areas
-get nutrients by slowly passing from cell to cell (diffusion)
-bryophytes eg)mosses, liverworts, and hornworts
vascular plants
-have specialized tubes to transport water and food around plant.
-2 types:
1. xylem- water and nutrients from roots to rest of plant
2. phloem-food from leaves to rest of plant
-allows plants to be tall and found on land eg)ferns, trees
which period did bryophytes arise
ordovician period ~475mya
Which plants are embryophytes?
-land plants
-complex multicellular eukaryotes with reproductive organs
-mostly autotrophs but can be heterotrophs
derived traits
traits that appeared by mutation which come from their most recent ancestor
which adaptations allowed plants to move to land
1.adaptations for reproduction
2. preventing dehydration
are algae photosynthetic. if so which algae
brown and green algae
bryophyte contraints
- moist enviornemts bc they have flagellated sperm
- short bc they lack a vascular system, roots, and leaves
key adaptations of bryophytes (5 derived traits of land plants)
- embryophytes-retained their multicelluar embryo and protected
- walled spores-to prevent spore from drying out
3.gamete production in gametangia (protects gametes) - growth by apical meristems (tissues on ends of leaves stems etc.)
- waxy cuticle and stomata (except liverworts. they have stomata like openings that cant open and close. and no cuticle so the plant takes up water over entire surface)
phylum of bryophytes
liverworts, hornworts, and mosses
stomata
pores that open and close by guard cells and exhchange gases. water is also let out by water vapour
gametangia
an organ or cell in which gametes are produced that is found in many multicellular protists, algae, fungi, and the gametophytes of plants.
a gametangium is a haploid structure and formation of gametes does not involve meiosis.
which period did seedless vascular plants rise
silurian period ~420mya
which phylum are included in seedless vascular plants
horsetails, clubmosses, and ferns
key adaptations of seedless vascular plants
vascular tissue-allows for reduced height constraint, structural support and efficent transport of water, nutrients and food
4 plant phylum
Plantae are made up into four phylum: Angiospermorphyta (anthophyta), Coniferophyta, filicinophyta (pteridophyta), and Bryophyta, or flowering plant, conifer, fern, and moss, respectively.
how are tall plants advantageous? what was the one consequence of growing taller?
they are able to capture more sunlight
more photosynthetic activity caused decrease in atmospheric CO2
constraint of seedless vascular plants
still had flagellated sperm and need periodically moist enviornments for fertilization.
where would seedless vascular plants be most abundant?
in moist enviornments where it may rain alot like BC
gametophyte vs sporophyte
The sporophyte (2n) generation is represented by the asexual phase, while the gametophyte (n) generation is represented by the sexual phase.
are charophytes haploid or diploid?
haploid since they only hsve gametophytes (flagellated sperm) therefore no sporophyte
sporangium
A sporangium is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular.
Seed plants possess both male and female sporangia. A female sporangium produces a female spore, which develops into a female gametophyte (egg). same w males but develop into sperm
what are the gametophytes in flowering plants
the pollen grain is the male gametophyte and the embryo sac is the female gametophyte
ancestral traits vs derived traits
ancestral=traits that stayed in species from
its ancestor.
-reflects ancestors, evolutionary origin
derived= traits that
evolved bc of enviornment-innovative
-reflects adaptations and are not
found in ancestors
example of mutualism relationship
pollinators and plants (angiosperms) benefits both of them
whcih period did angiosperms rise
jurrassic ~142mya
key adaptation 2 of gymnosperms (3 characteristics)
pollen
-male gametophyte protected by spore coat
-sperm in pollen
-pollen travels by wind
how are flowers advantageous
-requires less pollen production
-higher reproductive succes (pollinators)
-effective even at low population density
coevolution of plants and pollinators (2)
-flowers exert pressures on bees: bees changed physilogically like more hair, body shape to effectively transport pollen
-flowers favouring bilateral symmetry in colours like blue and yellow
bees have exclusive access to nectar
darwins theory of coevolution
orchid that had long spurs and nectary tip. darwin predicted a long tongue moth would be found that pollinates it
2nd key adaptation or angiosperms
fruit:
fleshy structure, ovaries
helps to protect dormant seeds
charophytes and land plants
more similarities between these two than chlorophytes and land plants
like:
1. cell wall composition
2. cytokenesis
3. biochemistry
4. sperm ultrastructure
charopphytes are closest relatives of land plants
adaptation to grow on dry land
- waxy cuticle (prevent water from evaporating out bc of waxy layer)
- stomata (open and close to retain water)
3.vascular tissue (xylem able to suck water from roots-underground-to rest of plant
adaptation to defy gravity
vascular tissue provided structural support (only in some animals). liginified vascular tissues (cell wall of xylem has lignin in it- a hydrophobic component that also provides structure)
flavonoids
adaption to provide protection from uv rays for plants
carbon structures
in all but hornworts
sporophyte and sporangium
sporangium is a structure of a sporophyte where apores are formed
adaptions to reproducing on land (4 but idk if theres only four)
- walled spores-to prevent dessication
2.gametes produced in multicellular gametangia (not in angiosperms)-protects reproductive cells
3.embryophtes (embryo develops in female gametophyte/maternal tissue-protects embryo)
- alternation of generations (can switch between asexual and sexual and is advantageous as they can adapt to enviornmental consitions)
advantage of sporophyte dominant life
Advantage of a dominant sporophyte was fertilization and dispersal of new/next generation timed with environmental conditions. therefore diploid spore responds better to environment
eg)seeds will only germinate when conditions are right
homosporous or heterosporous
homosporous= plant only produces one type of spore that gives rise to bisexual gametes
eg) C-fern
heterosporous= male or female spore that gives rise to either male or female gametes
where do angiosperms produce gametes
theyre flowering plants so in the parts of flower; anther and ovule
(other plants have gametangia that produce gametes)
What is the difference between gametangia and gametophyte?
Gametangia is the sex organ that produces gametes in plants, 2. A Gametophyte is a haploid phase in the plant life cycle that produces gametes.
