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