Plant biodiversity 2 Flashcards
what is a sphenopsids breeding strategy?
homosporous
what shape are sphenopsids sporangia?
cone shaped
what is the embryogeny of sphenopsids?
exoscopic
how many groups of ferns are there and which is most abundant?
6 and polypodiales are most abundant
what are ferns breeding strategy?
most are homosporous except for a few heterosporous forms
where are sporangia located on ferns?
on the underside of the leaf
what is the embryogeny of ferns?
endoscopic
what are Eusporangiate?
sporangia that arise from a group of epidermal cells
what are leptosporangiate?
sporangia developed from a single epidermal cell
describe the origin of leaves for microphylls
outgrowths which eventually become vascularised
describe the origin of leaves for megaphylls
gaps between parts of outgrowths become filled in with leaf tissue as an advantage to get increase surface area for sunlight and to stop sunlight reaching plants below reducing competition
where does sporangia form on ophioglossales
form on a fertile spike growing out the top of the plant
Do psioltales have leaves?
no they have outgrowths called enations
describe the sporangia and spores of marriatales
sporangia are fused into synangia and spores are monolete (single spore)
how do osmundles release their spores?
cells full or air surrounding sporangia which burst releasing spores
Describe the reproductive strategy of hydropteridales
they are heterosporous and roots have microspores which join with megaspores at surface of the water this joining causes a change in density and sporophyte sinks to the bottom and grows into a plant
how do polypodiales sporangia develop?
the entire sporangia develop from one initial cell - the sporangia are very small
what are 2 advantages of developing seed habit?
1) loss of need for free water - exploit more habitat
2) parental control over when the seeds are released depending on the correct conditions
when did gymnosperms dominate?
throughout the mesozoic
what are the 4 phyla of extinct gymnosperms?
1) pteridosperms
2) cordaites
3) glossopterids
4) Voltziales
what are the 4 phyla of extant gymnosperms?
1) ginkgos
2) cycads
3) conifers
4) Gnetales
what are 3 features of ginkgos?
1) male or female reproductive structures occur on different plants in the axils of scale leaves
2) ovules are borne in pairs
3) sperms have flagellum to swim down to ovule
what are 3 features of cycads?
1) seeds are poisonous
2) males and females are separate plants
4) females produce cones which either grow out the top of the plants either terminal or lateral
describe the reproductive strategy of conifers
reproductive organs in cones, male gametes are delivered by a pollen tube into cone which closes once fertilised protecting the seed over winter and then releases once the weather is right
how are seeds of conifers dispersed?
wings help them to be dispersed by air but some are grown in fruits for dispersal by animals
how many species of Gnetales are there?
160
3 facts about Gnetales
1) pollinated by beetles
2) closely related to conifers
3) have flower like structures
what is mosaic evolution and where is it common?
during times of environmental stress plants can adapt by a single organ evolving, say leaves, while essentially maintaining their genetic makeup, its very common in plants
3 important features of land plants
1) asexual reproduction is common in the plants kingdom
2) polyploidy is common
3) plants can readily hybridise
are population size dynamics a problem in the plant kingdom?
no very small populations can persist
what are the 4 living fossils?
1) gymnosperms
2) bryophytes
3) sphenopsids and ferns
4) lycopsids
what did algae give rise to?
liverworts, hornworts, tracheophytes and mosses
is the tempo and mode of evolution different for plants and animals?
yes plants recover post trauma much better the animal kingdom is mainly shaped by mass extinctions
what drives plant evolution?
major plant groups often persist rather than face extinction sometimes they have a new lease of life e.g. bryophytes as epiphytes
what are the 4 main things that drive plant evolution?
1) environmental change
2) climate change
3) atmospheric composition
4) land surface area
what happened to plants in the middle silurian?
switch from gametophyte dominant to homosporous sporophyte dominant
what happened to plants in the early devonian?
plants became lignified and heterosporous plants evolve = 1st seed plants
what happened to plants in the late carboniferous?
increase in plants cause decrease co2 and shift to ice age world - plants store carbon in swamps and coal and CO2 put into oceans in limestone
what happened to plants in the late permian?
wilson cycle caused a madd extinction and volcanic eruptions caused super heating
what happened to plants in the early triassic?
world became dominated by gymnosperms
what happened in the late jurassic?
continents fall apart and there is a mass extinction
what happened to plants in the late cretaceous?
angiosperms dominate over gymnosperms
