exam 1 (lecture 4ish-6) Flashcards
shared features of charophytes and land plants (synapomorphies)
cell divides by phragmoplast
rose-shaped complexes for cellulose synthesis in cell wall
phragmoplast
group of microtubules that form between daughter nuclei in mitosis (cell div)
phragmoplast v phycoplast
phrag - charo and land plants (perpendicular to plane of div)
phyco - chlorophyceae, parallel to plane of div
diversity of charophytes
most zygne then charales then coleo
less diverse than chlorophyta
dunaliella atacamensis
class chlorophyceae
grow on spider webs in desert, live off dew
atacama desert
dunaliella salina
order chlorophyceae
hypersaline enviro
high conc of carotenoids - protect from UV sun
high conc of glycerol protect fr osmotic pressure
red/pink lakes
used as antioxidant, nutritional supplement
first land plants
bryophytes
embryophytes
land plants, begin w bryophyte
bryophyte phylogenic group
paraphyletic
date for bryophytes
475 million years ago
bryophytes
non-vascular
small
found everywhere but love moist places
3 phyla of bryophytes
Marchantiophyta (liverwort)
bryophyta (moss)
Anthocerophyta (hornworts)
Synapomorphies for bryophytes
- male and fem gamentangia (archegonia and antheridia)
- multicellular diploid sporophyte
- resistant spores with sporopollenin
sporopollenin
protest spores from harsh conditions on land
only land plants
life cycle of bryophyta
sporic meiosis, alternation of generations
gametophyte (free living) is base and dominant phase
sporophyte is appendage on haploid (dependent)
diff in sporophyte between seed plants and bryophyte
in bryo, gametophyte is free living
in seed, sporophyte (2n) is larger, free living form w small gametophyte
marchantia
liverwort (marchantiophyta)
haploid thallus
life cycle details of bryophytes
water transfer spores to achegonia (they release chem to attract sperm)
thalloid veg structure of bryophytes
simplest, has rhizoids to attach to substrate (no vasc func)
all hornworts, some liverworts
leafy veg structure of bryophytes
all mosses, some liverworts
more complex
asexual reproduction of bryophytes
many liverworts and mosses
gemma - derived by mitosis, asexual reproductive structure
gemmae splash out of cup from rain
develop into new gametophytes identical to parent
embryo development of marchantia (bryophyte)
zygote remains in achegonium where nourished by gametophyte to develop into embryo
placenta (transfer cells) allows for nutrient transfer from gametophyte to sporophyte
maturation of sporophyte
diploid
mature sporangium open to release spores
operculum cap opens when dries out
most diverse phyla of bryophytes
mosses/bryophyta (10K)
liverwort/marchantiophyta (6K)
300 hornwort/anthocerophyta
anthocerophyta/hornworts
only thalloid, unicell rhizoids one chloroplast/cell least div ecological pioneers most have photosynthetic sporophytes with stomata
marchantiophyta/liverworts
thalloid or leafy
unicell rhizoids
many chloroplasts/cell
bryophyta/mosses
only leafy
multicell rhizoids
many chloroplasts/cell
bryophyte sister to vasc plants?
hornworts/anthocerophyta even tho most simple
totipotent cells
capacity of living cell to de-differentiate into meristematic state where cell can then differentiate into any structure (like stem cells)
poikilohydry
capacity of org to experience extreme dehydration and fully recover
shut down during dessication and revive later
haplontic life cycle
zygotic meiosis
mitoses only occur in haploid phase
hpaloid dom
most green algae
diplontic life cycle
gametic meiosis
mitoses only occur in diploid phase
humans, animals
diploid dom, multicellular
biphasic or haploid-diploid life cycle
sporic meiosis
cell div and vegetative growth occur in both haploid and diploid phases
land plants
multicell hap and dip
number of mutations
dip v hap
dip - more mutations b/c 2X the targets
efficiency of nat select - dip v hap
hap - all new mutations expressed
dip - new mutations can be MASKED
deleterious mutations
more efficiently elim and have lower eq freq in haploids
advantageous mutations
more efficiently fixed in haploids
less likely to be lost by chance. masking in dips causes fitness benefits of mutations to be partially lost
somatic deleterious mutation
during development, not meiosis
favor dip
a hurtful allele can be masked
larger organisms with more cell types often have expanded diploid pahse
heterozygote advantage
diploids
Hosts could have two alleles for parasitic recognition
Good for plants!!
heterozygote disadvantage
parasites
2X ways to detect by hosts
bad
tracheophytes
vasc land plants
monophyletic
changes from bryophytes to lycophytes
- larger sporophytes
- lignified tracheids (xylem conducting tubes)
- vasc tissue w xylem and phloem
oogamy v isogamy
oogamy - diff gametes (egg and sperm)
isogamy - gametes have similar morphology, ‘mating types’
1st vascular plant
cooksonia
time of vasc plants
400 million
flowerign plants time
200 million
carboniferous period
warm/wet swamos
362-290 million yr ago
extensive fossil fuel accumulation
tall versions of ferns, horsetails, and lycophytes that are extinct
cooksonia
extinct vascular plant
only sporophyte (dip) known from fossil
branched
vv small
3 tissue systems of plants
dermal - prevent water loss, protective
vasc - xylem and phloem
ground - rigidity, bulk, storage, photosynthesis
stele
central column of vasc tissue in stem and root
xylem in middle then phloem
