Being Multicellular Chapter 28 Flashcards
__ multicellularity is widespread amongeukaryotes
simple
simple multicellular organisms have __ but most importantly __
full range of functions; always in direct contact w/ cell environment
advantages to multicellularity
avoid getting eaten, maintain position better, feeding, float better
disadvantages to multicellularity
cheating–using nutrients for own good aka cancer
complex multicellularity evolved
at least 6 times
complex multicellular organisms share 3 features
mechanisms for adhesion between cells
specialized structure for communication
complex patterns of cellular & tissue differentiation (can be deadly for organism)
only some of the cells in multicellular organisms are in..
direct contact with environment
most prokaryotic organisms are ____ and some live in___
single celled; colonies
diffusion is effective only over __ and is __
short distances; slow
how do we get around diffusion?
by pumping blood
why did many aquatic organisms increase their surface area?
to increase drag
-reduces their rate of sinking and allows them to float w/o expending more energy
what is bulk flow?
means by which molecules move through organisms at rates beyond those possible by diffusion across concentration gradient
-distributes nutrients
also carries developmental signals
how do plants manage bulk flow?
through system of tissues powered by evaporation of water from leaf surfaces
how do fungi use bulk flow?
use filaments to transport using osmosis
complex multicellularity requires __ between cells. how is this accomplished?
adhesion; transmembrane proteins: cadherins, integrins
in plants, pectins
why did adhesion come about?
maybe to stick to rock/sediment/capture bacteria
aids in predation (choanoflagellates)
complex multicellularity requires ___ via molecular signals
communication
complex multicellular organisms have ___ that allow for targeted communication in animals
gap junctions
how do plants communicate?
plasmodesmata
allows for targeting as well as opening in cell walls
complex multicellularity requires a ___ for coordinated growth and cell differentiation
genetic program
development in cells is a results of
molecular communication, 2 cells in the same organism can be exposed to different environments
the innovation of complex multicellularity was to differentiate cells in ___ instead of ___
space; time
plants have patches of tissues on ___ whereas animals have it on __
outside; inside
___ shape patterns of growth and development in plants
cell walls
plants can’t move, so what happens?
they have meristem tissue that acts as embryonic tissue as long as the plant is alive
how are plants and animals different?
- animals’ cell division & tissue diff. occurs throughout their developing bodies
- animals can move their muscles
do plants and animals have a common ancestor?
no
when did we first find evidence of complex multicellular organisms?
579-555 mya
what is absolutely necessary for complex multicellular life?
oxygen
when did oxygen first accumulate?
2400 mya, levels remained low abundant around 580-560 mya
land plants evolved from
green algae that could carry out photosynthesis on land
complex land plants first came about when?
465 mya
