Chapter 8: Leaving the Water

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Challenges

drying out - smaller org. more susceptible because of large surface area without large body size

temperature extremes greater

O and CO2 behave differently in air than in water

Vision and Hearing both change

food supply - air does not have nutrients readily available, change in feeding habits

gravity

Change in feeding style happens before change in habitat

Land plants

structural or hydrostatic pressure supports (hard cuticles or wood) to help them stay upright

waterproofing

roots gather water and nutrients and act as props and anchors

Internal transport systems

reproductive cycle that is adapted to the air

^hard to get evidence because the first land plants would have been soft-bodied, preventing a clean fossil record

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green algae theory - plant

already developed some type of spore that could be released in the air

has developed a transport system between cells to move food around plant

some cells reach out of the water, and absorb CO2 and photosynthesize more rapidly

^ the tissues no longer are surrounded by water and are prone to drying out

"conducting strand" - piping system of cells to carry water upward

development of cuticle (waxy layer) over exposed areas

^ wet times = waterproof coating to prevent blockage of CO2

^ dry times = sealant to prevent water from leaving

*leaves do not absorb water!!!*

roots develop from runners

symbiotic relationship with fungi and bacteria

stomata pores - concentrated CO2 uptake

^ guard cells

"intercellular gas transport system"

plants become polarized

^ Xylem (vascular plants only) transports water and minerals upward from the roots to the leaves

^ Phloem transports food around the plant from the leaves where it is made

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Plants are more vulnerable to extinction by competition

Plants are more vulnerable to climate change

Plants are less vulnerable to mass