lecture 08 - resource constraint: water Flashcards
why does the heat not kill you?
dehydration does
water = life?
essential to organisms as most are comprised of 50-90% water
must maintain internal concentrations of substances like salts to survive
ppt
parts per thousand unit for concentrations
freshwater ppt
5 ppt
estuaries ppt (brackish environment)
10-25 ppt
oceans ppt
35 ppt
what accounts for salinity in bodies of water?
sodium or sulfates
diffusion
movement of soluble salts or water due to random movement of particles (salt concentrations are equalized in a solution)
osmosis
movement through a semipermeable membrane, such as a phospholipid cell membrane (it is permeable only to some molecules, such as water)
osmolarity
refers to the amount of solute/water in a solution in relation to a reference (its environment)
hypoosmotic
low solute concentration, high water concentration
organism has higher water concentration and lower solute concentration than the environment
hypersmotic
high solute concentration, low water concentration
organism has lower water concentration and higher solute concentration and solutes as the environment
isosmotic
same solute and water concentration
organism has the same water concentration and solutes as the environment
hypoosmotic marine organisms
low osmotic pressure in blood
risk dehydration and surplus intake through gills
solutions to hypoosmotic marine organisms
drink constantly to counteract dehydration
low urination rates and volumes
get rid of excess salt through specialized chloride cells in the gills (adaptation)
isosmotic marine organisms
internal body concentrations of salts and water are equivalent to the concentration in their external environment
hyperosmotic marine organisms
risk too much water entering the organism and too many salts leaving the organism
solutions to hyperosmotic marine organisms
do not drink
excrete excess internal water via large amounts of dilute urine
replace salts by absorbing sodium chloride in gills and by ingesting food
fish that move between salt and fresh water
acclimate to salinity of their new environment (reversible physiological change)
anadromous
born in freshwater, spends most of its life in the sea, and returns to freshwater to spawn
catadromous
born in the ocean, spends most of its life in freshwater, and returns to the ocean to spawn
water potential
water moves from high to low water potential, if there are differences in water potential, water will move
where is the lowest water potential in plants
tree canopy/tree trunk
why is the lowest water potential in the canopy and trunk
leaf surface interfaces with the air causing evaporation and transpiration
water acquisition in terrestrial plants
acquisition of water in roots is essential for the water pump to work but water is limited in many environments
what is the root adaptation for plants in dryer climates
roots grow deeper into the soil to acquire water found in deeper soil layers or at the groundwater level
water acquisition in terrestrial animals
drinking food and water
water conservation in terrestrial animals
think waxy cuticles to avoid water loss
protective and waxy or hard layer covering the epidermis of a plant, invertebrate or shell
storing water when it’s available and releasing it slowly in period of drought
conservation of urine, feces and sweat to minimize water loss
behavioural adaptations to minimize water loss
water conservation in terrestrial plants
wilting as a strategy to reduce water loss
