Water Constraints Flashcards
How much dehydration can mammals tolerate?
12-14% dehydration
What are water budgets?
All organisms regulate their internal water concentration by balancing water inputs with water outputs
What are the main avenues of water regulation?
Water gain through drinking
Water loss through secretion
Water loss/gain through osmosis
How does deeper water affect salinity?
Deeper = more salt
What is osmolarity?
Refers to the amount of solute/water in a solution in relation to a reference system
What is a hypoosmotic condition?
Low solute concentration, high water concentration
An organism has higher water concentration than environment
What is a hyperosmotic condition?
High solute concentration, low water concentration
Organism has a lower water concentration than environment
What is an isosmotic condition?
Same solute and water concentration
Organism has the same water concentration as environment
What is the salt-water balance in marine organisms?
Most marine fish and invertebrates are isosmotic
What is the salt-water balance in freshwater organisms?
Most freshwater organisms are hyperosmotic
Risk surplus water inflow and loss of salts
How does freshwater organisms adapt to freshwater conditions?
Do not drink
Excrete excess internal water
Replace salts by absorbing Na/Cl in gills and by food ingestion
What is the salt-water balance in saltwater?
Many saltwater fish are hypoosmotic
Low osmotic pressure in blood
Risk of water loss and surplus salt intake
How do saltwater organisms adapt to saltwater conditions?
Drink to prevent dehydration
Low urination rate
Gets rid of excess salt through cells in gills
What are sharks/skates and how do they cope with those conditions?
Hyperosmotic
Retain urea in blood to avoid osmotic water loss
Surplus water gain is counteracted with urea production
How do anadromous fish acclimate to the salinity of their new environment?
Born in fresh water spends most of its life in the sea and returns to fresh water to spawn
How do catadromous fish acclimate to the salinity of their new environment?
Lives in fresh water and enters salt to spawn
How do animals gain and lose water?
Gain = drinking, food, air
Loss = evaporation, secretion
How do plants gain and lose water?
Gain = roots, air
Loss = transpiration, secretion
How do vascular plants gain water?
Through root uptake via water potential, water moves from high to low water potential
What is water vapour density?
Quantity of water vapour that air actually holds
What is saturation water vapour density?
Quantity of water vapour that air can potentially hold
What air can hold more water?
Warm air can hold more water than cold air = high water vapour pressure
What is the water potential in all parts of the tree?
Soil>roots>tree trunk>tree canopy
What is 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
Deep roots help plants acquire more water
