Lecture 14: Land Plants Flashcards
what is a major way that plants differ from protists?
-plants are multicellular
challenges to land living?
- drying out (need to survive long term in air)
- structural support by itself (w/o the support of a water column)
- reproduction (dependent on water to transport gametes so they gotta find a new way to reproduce)
adaptation to land
- embryophyte
- cuticle
- stomata
- pigmentation
- fungal relationship
- tracheid cells
- seeds
embryophytic adaptation
-have structure to protect developing embryo and prevent it from drying out
cuticle adaptation
-waxy substance that traps water inside of plant thus hard to get air in which has CO2 which is necessary
stomata adaptation
-holes that open to let air in, then close to keep water in
pigmentation adaptation
-blocks out UV rays since water no longer will
fungal relationship adaptation
-having a relationship with soil fungi helps them get nutrients
tracheid cells
-specialized cells that allow for water and nutrient transport from the roots to the leaves
tracheid cells adaptation
-allows the plant to become much larger organisms
seeds
-ultimate form of embryo protection
diplontic life cycle
- have only diploid stages of life(multicellular)
- gametes never undergo mitosis
haplodiplontic life cycle
- have multicellular, haploid, and diploid cycles
- almost all plants have two forms (haploid gametophyte and diploid sporophyte)
- have multicellular haploid and diploid stages
sporangia
- specialized structures in the sporophyte
- where diploid spore mother undergoes meiosis and produce haploid spores
spore mother cells
-in sporangia, undergo meiosis and produce the haploid cells
spores
-any haploid cell that will divide by mitosis and become multicellular
archegonium
- produces eggs
- where mitosis of gametophytes occur
antheridium
- produce sperm
- where mitosis of gametophytes occurs
syngamy
-the fusion of gametes (fertilization)
gametophyte
- haploid generation that gives rise to gametes
- alternates with sporophytes
how do the events of meiosis and syngamy shape the haplodiplontic life cycle?
- meiosis goes from diploid to haploid
- syngamy goes from haploid to diploid
dominant life stages traits
- varies within in plants
- haploid stages sensitive to recessive mutations
rhodophyta
- aka red algaes
- outgroup
- vary in size
- color comes from accessible photosynthetic pigment, many don’t appear tho
- makes nori
chloroplast formation
- result from primary endosymbiosis
- led to chloroplasts with two membranes
- brown algae is an example of secondary endosymbiosis
primary endosymbiosis
-single event that gave rise to green and red algae
secondary endosymbiosis
-when a new lineage gain photosynthetic ability by engulfing a product of the primary photosynthetic event
chlorophyll types
- chlorophyll a: land plants, red, brown, & green algae
- chlorophyll b: green algae, land plants
- chlorophyll c: brown algae
which chlorophyll type is found in cyanobacteria?
-chlorophyll a
chlorophytes
- contains most green algaes
- monophyletic, unicellular and multicellular
- share a flattened cell form w/ most land plants
- some are haplodiplontic
- types: chlamydomonas, volvox
chlamydomonas
- primitive chlorophyte
- green algae
- unicellular
volvox
- colonial, mobile, complex
- most aren’t reproductive
- represents an early form of multicellularity
stoneworts
- sister to land plants
- filamentous form
- homologous traits with land plants(mitosis style, cell structures)
- types: chara sp.
- show branching apical growth
apical growth
-growth from only the tips of the organism
chara sp.
- part of stoneworts
- form green mats around edges of freshwater ponds
- able to adapt to dry environments
what does non-vascular cells mean?
-no tracheid cells
bryophyte traits
- embryophytic
- gametophyte dominant (thus plants spend most of their life haploid)
- sporophyte grows out of gametophyte and is dependent on gametophyte for nutrition
- require water for sexual reproduction(for gametes to float in)
- not photosynthetic
non-vascular plants
- aka bryophytes
- liverworts, mosses, hornworts
liverworts
- part of bryophytes
- gametophyte stage
- not as efficient as tracheids and can’t move things very far(so they’re short)
moss
- part of bryophytes
- doesn’t have true leaves
- work well in extreme climates
- really vulnerable to recessive mutations
hornwort
- part of bryophytes
- sporophyte stage
moss life cycle
- gametophyte dominant, requires water
- sporophyte completely dependent on gametophyte for nutrition b/c it itself doesn’t do photosynthesis
- really vulnerable to recessive mutations
xylem
-brings water and minerals up
benefits of tracheid cells
- allow plants to get tall
- have stiff cell walls and give plants structure(allows them to stand)
phloem
-brings sugar and nutrients down
seedless vascular plants (tracheophytes) traits
- embryophytic
- sporophyte dominant (diploid)
- free-living gametophyte (lacks vasculature)
- can get very large
- types: lycophytes, monilophytes
lycophytes
- aka club mosses
- most primitive tracheophytes
- small
- have microphylls
microphylls
- weed-like structures
- leaves without vasculature
- arranged around stem in spirals
megaphylls
- true leaves
- with vasculature
- veiny leaf
monilophytes
- monophyletic
- sisters to seed plants
- 1st group to have megaphylls
types: horsetails, ferns
sori
- clusters of sporangia release the spores
- unite the ferns
fern life cycle
- sori have spore mother cells, undergo meiosis and release haploid cells which are wind dispersed, will germinate in soil
- embryo develops into archegonium and as soon as its able to photosynthesize the gametophyte will die and the sporophyte will be independent
giant sequoia
- aka sequoiadendron giganteum
- biggest organism on earth
coast redwood
- aka sequoia sempervirens
- tallest organism on earth
horsetails
- no leaves
- photosynthetic stems
- have rings of actively dividing cells that can regrow if you cut off the top
ferns
- dominant the tracheophytes
- vary greatly in size
