Lec 8- water constraints

Question 1

What kills humans?

Answer 1

dehydration
- increase in temps outside of tolerance leads to water loss which kills them

Question 2

How much of a human is water?

Answer 2

50-90%

Question 3

water content of human male?

Answer 3

60%

Question 4

water content of jellyfish?

Answer 4

95%

Question 5

water availability?

Answer 5

planet hostile to organisms bc water is limited
- limited esp in desert environments but is limiting in all

Question 6

water budget

Answer 6

• organisms regulate internal water concentration by balancing water inputs w outputs
• inputs and outputs differ b/w plants and animals and b/w terrestrial and aquatic animals

Question 7

water budget eqn

Answer 7

main avenues of water regulations
Wi= Wd - Ws +/- Wo
internal water, drinking, secretion, osmosis

Question 8

salinity in aquatic sys

Answer 8

regulation of water important for aquatic organisms b/c diff salt concentrations in aquatic sys
- fresh = 5 ppt
- estuaries = 10-25 ppt (brackish water)
- oceans = 35 ppt

Question 9

saline and brackish

Answer 9

salt marshes and lakes in eastern AB
- lakes display a wide range of salinity and diff ion content

Question 10

osmolarity

Answer 10

osmotic concentration
- refers to amount of solute and water in a solution in relation to reference sys
- water moves down water gradient through membrane and twds solutions with higher salt concentrations until water concentration is equalozed

Question 11

hypoosmotic

Answer 11

low solute and high water

Question 12

hyperosmotic

Answer 12

high solute and low water

Question 13

isosmotic organism

Answer 13

organism has same water concentration as environment

Question 14

hyperosmotic

Answer 14

organism has lower water concentration as environment
- higher concentration of solute inside
- can become overflushed with water

Question 15

hypoosmotic

Answer 15

organism has higher water concentration

Question 16

freshwater fish

Answer 16

most are hyperosmotic
- internal water concentration is lower in external environment
- risk surplus water inflow and loss of salts

Question 17

freshwater fish

Answer 17

do not drink water
excrete excess internal water- large amounts of dilute urine
- replace salts by absorbing sodium/chloride in gills by ingesting food

Question 18

marine fish

Answer 18

most are isosmotic
- internal body concentration of salts and water equivalent to external environment

many marine fish = hypoosmotic
- risk loss of water and surplus salt intake through gills
- drink to counteract dehydration
- specialized chloride cells in gills to rid of excess salts

Question 19

sharks/skates

Answer 19

slightly hyperosmotic
- retain urea in blood to avoid osmotic water loss
- surplus water gained through gills is counteracted by urea production in kidneys
- when sharks die the urine is broken down into ammonia

Question 20

anadromous

Answer 20

acclimate to salinity of new environment
- born in freshwater but spends most of life in sea then returns to freshwater to spawn
- salmon, smelt, shad, striped bass, sturgeon
- most common

Question 21

catadromous

Answer 21

lives in freshwater but spawns in salt
- most eels

Question 22

salmon

Answer 22

anadromous
- cope w changes in salinity and water concentration through shifting secretion cells from taking in salt to freshwater
to
excreting salt in marine

Question 23

water regulation eqn - animals

Answer 23

Wi = Wd + Wf + Wa - We - Ws
drinking, food, air, evaporation, secretion

Question 24

water regulation eqn - plants

Answer 24

Wi = Wr + Wa - Wt - Ws
roots, air, transpiration, secretion

Question 25

how does water go up plants?

Answer 25

vascular plants gain water through root uptake

Question 26

water vapour density

Answer 26

quantity of water vapor that air actually holds

Question 27

saturation water vapor density

Answer 27

quantity of water vapor that air can potentially hold

Question 28

water vapor pressure

Answer 28

pressure exerted by water vapor in air

Question 29

saturation water vapor pressure

Answer 29

total pressure exerted by water vapor in water-saturated air

Question 30

does cold air hold less or more water vapor?

Answer 30

less
- low water vapor pressure

Question 31

does warm air hold less or more water vapor?

Answer 31

more
- higher water vapor pressure

Question 32

water potential

Answer 32

ability of water to do work
- water moves from high to low water potential
- if there are diff in water potential, water will move
- usually neg value
- ranges from 0 to -100

• the more neg, the lower the water potential

Question 33

water potential eqn

Answer 33

pure water + gravity + solute (osmotic pressure) + humidity + matric (matric pressure) + pressure (sum of extraneous pressures)

Question 34

water potential in plants

Answer 34

tree canopy: low water potential (most neg)
tree trunk: low to moderate water potential
roots: medium to high water potential
soil: high water potential
- potential becomes more neg allowing water to get pulled up and resist gravity as it goes up tree

Question 35

water acquisition - terrestrial

Answer 35

deep roots is a strategy to acquire water
deepest in dry climates

Question 36

water acquisition - animals

Answer 36

food and drinking
from respiration

Question 37

water conservation

Answer 37

thick waxy cuticles
hard layer covering epidermis of plants and body and shells

Question 38

camels and cacti water conservations

Answer 38

cacti: stores in trunks and arms
camels: water stored in blood stream
efficient kidney: urine highly concentrated and thick

Question 39

kangaroo rats and camels water conservation

Answer 39

low moisture feces
burrows = cooler and less transpiration

Question 40

water conservation- leaves

Answer 40

wilting
- reduce water loss and SA decreases during prolonged water stress and drop in turgor pressure