Evolution in Plantae Flashcards
what is a plant
an organism that obtains most of its energy from sunlight through photosynthesis
do all plants use photosynthesis
no, some have lost the ability
are all plants multicellular
no, some primitive algae are unicellular and are considered plants
how do plants reproduce
through the alteration of generation
some reproduce asexually
when and where did photosynthesis first appear
3.4 billion years ago in a bacterial cell
when did the first cyanobacteria appear
2.7 billion years ago
what are cyanobacteria
the first to use chlorophyll and the same basic mechanisms of plant photosynthesis
they have a range of pigments that use light in shallow and deep water
what is the endosymbiotic theory
an ancient eukaryotic cell engulfed a cyanobacteria
the cell used the cyanobacteria as an energy factory instead of digesting it
where does the chloroplast organelle evolve from
the engulfed cyanobacteria that used photosyntheis
what is the primary endosymbiotic theory
when the eukaryotic cell engulfs a cyanobacterium
a symbiont is formed
what is the secondary endosymbiotic theory
when a eukaryotic cell with a cyanobacterium symbiont is engulfed by another eukaryotic cell
how did green algae appear
it most likely arose from a group which had undergone primary endosymbiosis
when did the first green algae appear
0.75 billion years ago
what is green algae specialized in
using wavelengths of light found in shallow water
what are the barriers to adapting to life on land
- desiccation
- gas exchange
- reproduction
- buoyancy
- temperature fluctuations
- more light
- mineral nutrition
- harmful UV radiation
what is desiccation
when the aquatic organisms adapted to being surrounded by water dry out in open air
why do smaller organisms dry out faster than larger ones
surface area > internal space in small organisms
internal space = water storage
surface area = primary area of water loss
why can’t plants evolving from water to land be waterproof
they need to allow the passage of water and gasses in and out of the body
what does the plant need to absorb gases when evolving from water to land
a new system for gas exchange
why is reproduction hard for plants evolving from water to land
organisms need water to facilitate reproduction
why is buoyancy a barrier to adapting from water to land
water and water pressure supports body tissues
air doesnt
why are temperature fluctuations a barrier to adapt from water to land
water: temp changes are slow and have little change (max 4 degrees in a century)
land: temp changes are quick and have big change
(30 degrees in 24h)
why is more light a barrier to adapting from water to land
water filter out wavelengths of light
chloroplasts are optimized to absorb a specific range of wavelengths of light
why do plants need minerals
to grow
how is water optimal for absorbing minerals
minerals are in water and plants use filter feeding
what do plants need to develop to absorb minerals on land
a way to supplement nutrition loss
why are uv radiations a barrier to adapt from water to land
water can filter uv light and protect light
gas cant
how did plants evolve to protect themselves from uv radiation on land
more plants over time = more oxygen
more oxygen creates the ozone shield
ozone shield filters out enough uv radiation
how are soils today
- rich in organic matter
- made of small stones (sand, clay, silt)
- good at holding minerals
what is organic matter
complex compounds borken down by microorganisms
how were the small stones in the soil created
through chemical weathering of solid rocks
where was green algae found
in freshwater
along shorelines in shallow water
how did algae move on to land
algae was exposed to land for long periods of drought
what are the 4 main groups of plants
- seedless non-vascular plants
- seedless vascular plants
- gymnosperms
- angiosperms
what is another name for seedless non-vascular plants
bryophytes
when did seedless non-vasc evolve
470 MYA
470MYA what were the animals
all animal life was aquatic
what first appeared in seedless non-vasc
- terrestrial growth forms
- multicellular
what are the 3 main groups of seedless non-vasc plants
liverworts
mosses
hornworts
how does seedless non-vasc reproduce
by spores
what do seedless non-vasc plants NOT have
- vasculature
- flowers
- roots
- leaves/stems
what are characteristics of seedless non-vasc plants
they are all very small
where do we find seedless non-vasc
moist environments
what repro lifecycle is dominant for seedless non-vasc
gamteophyte
when did seedless vasc plants evolve
350MYA
what where the animals 350 MYA
- crawling arthropods (insects) dominate land
- first tetrapods begin to emerge on land
what first appears in seedless vasc plants
- roots
- distinct leaves and stems
- vasculature
- secondary growth
what are the 4 main groups of seedless vasc
- ferns
- horsetails
- club mosses
- whisk ferns
how do seedless vasc reproduce
by spores
what are the types of vasculature
xylem and phloem
what do seedless vasc NOT have
- flowers
where do we find seedless vasc
moist environments
what are seedless vasc characteristics
most are small
some tree forms
what is the dominant repro lifecycle
gametophyte
when did gymnosperms appear
245 MYA
what were the animals 245MYA
large reptile groups
basically the ancestors of dinosaurs who emerge 230MYA
what first appears in gymnosperms
seeds
what are the 4 main groups of gymnosperms
- cycads
- gingkoes
- conifers
- gnetidae
how do gymnosperms reproduce
by seeds
what do gymnosperms NOT have
flowers
where do we find gymnosperms
dry or temperate environments
what repro lifecycle is dominant in gymnosperms
sporophyte
when did angiosperms first evolve
160MYA
what were the animals 160MYA
dinosaurs dominated
small mammals start to appear
what first appears in angiosperms
flowers
what plant group dominates now
angiosperms
what are the 4 main groups of angiosperms
- eudicots
- magnolids
- monocots
- basal angiosperms
how to angiosperms reproduce
seeds
where are angisperms found
moist environments
sometimes in water or deserts
how did plants defeat desiccation through evolution
- multiple cell layers on the epidermis
- layer of wax
- roots/root-like structure
all help hold in water or direct water to the plant
how did plants evolve their gas exchange mechanisms
- specific pores allow gas to enter (stomata)
- pores close to prevent drying out
how did plants evolve to reproduce on land
- spores that survive desiccation that only need water to move
- seeds that only need water to germinate
how did plants defeat buoyancy through evolution
- strong fibers/ compounds for structural support (lignin and cellulose)
how did plants defeat temp fluctuation on land through evolution
temp regulated thanks to
- roots
- epidermis is thick
- wax layer
how did plants adapt their mineral intake through evolution
- roots allow mineral intake
- certain elements taken out of the air
- some plants take minerals through leaves
