plant form and function

shoot system

harvests light and carbon dioxide from atmosphere to produce sugars

root system

anchors plant and takes in water and nutrients from soil

roots

absorbs water and nutrients

shoots

aborbs light

what are the functions of roots?

anchor plants, absorb ions and water from soil, conduct water and ions to shoot system, obtain energy from sugar in the shoot system, and store material produced in the shoot system for later use

morphology of roots

depends on environmental conditions, reduces competition for nutrients and water, phenotypic plasticity throughout the geographic range of a plant

stem

vertical aboveground structure

leaf

appendage that projects from stem laterally

axillary bud

bud that forms at a node and may develop into a side branch

morphology of shoots

highly variable in size, influenced by light/wind/water, phenotypic plasticity throughout geographic range

simple leaf

one blade and one petiole

compound leaves

blade that is divided into series of leaflets

doubly compound

rainy, windy environments

needlelike compound leaves

dry, hot, or cold environments

osmosis

movement of water across a membrane from regions of lower to regions of higher concentrations

diffusion

movement of molecules across a membrane from regions of higher to regions of lower concentrations

water potential

potential energy in a given environment, compared with potential energy of pure water at atmospheric pressure and room temperature

which way does water move in water potential?

from high to low water potential

solute potential

movement of water by osmosis in response to differences in solute concentrations

isotonic

solute potential the same

hypotonic

solution has lots of solute inside cell, water moves inside, cell swells

hypertonic

solution has lots of solvent outside cell, water moves out, cell dries out

pressure potential

movement of water in response to pressure

wall pressure

water pushes against to maintain shape

turgor pressure

water pushes from inside cell to expand

where does water move in salty soils

away from root cells because there is a high solute concentration outside

where does water move in dry soils

water is stuck to soil particles and cannot be pulled in by roots

salt bladders

found in root cells and lowers solute potential to draw in water

transpiration

water evaporates from stomata pulling water from roots through shoots; driven by water potential, stomata must be open

root hair

increases SA:V ratio

endodermis

tissue/skin that protects phloem and xylem

phloem

vascular tissue, two-way street

xylem

vascular tissue, one-way street

guttation

root pressure forces water droplets out of leaf margins

surface tension

upward pull at top of the water column

adhesion

upward pull at the water-container surface

cohesion

water molecules stick to one another

cohesion-tension theory

water pulled from roots to the top of trees via water-potential gradient

photosynthesis-transpiration compromise

cannot maximize photosynthesis and have zero dessication, so plant has adaptations such as thick cuticles, stomatal crypts, trichomes, and alternative photosynthetic pathways

stomatal crypts

little caves where stomata hang to create cooler conditions

trichomes

tiny little hairs all over plants

translocation

movement of sugars through plant by bulk flow from sources to sinks through the phloem

what is the phloem made up of?

sieve tube elements, companion cells, and sieve plates

sieve tube elements

primary sugar conducting cells found in phloem tissue

companion cells

allows movement through plasmodesma

sieve plates

honeycomb structure that slows down sugar to prevent a rush

pressure-flow hypothesis

pressure potential gradient in phloem created by processes in sources and sinks