5.9. (9/23) Water, Energy & Nutrient Relations Flashcards
halophytes
- salt-tolerant plants
- can tolerate very high internal solute concentrations
- they have specialized enzymes and other adaptions
What special adaptions do mangroves have to deal with salt?
- leaves get thicker with increasing salinity
- exclude 99% of salt from their roots
What is salt exclusion?
What is salt secretion?
glands excrete salt through roots, shoots, and leaves
- accumulate in organs and then release
If halophytes do not secrete salt what do they do?
they are more efficient at exclusion
What is succulence?
holding on to water until conditions improve for photosynthesis
- increasing the water content per unit area of leaf to dilute the concentration of salt
- expanding cells
- leaf number decreases
- can be observed in arid areas that are not saline, but this is for water storage
How can succulence be a feature of phenotypic plasticity?
succulence can increase in response to changing salinity
What is phenotypic plasticity?
adapting to daily abiotic changes
What problems do freshwater fish experience with maintaining water balance/equilibrium?
- osmotic pressure
- more solutes inside
- water constantly moves into cell
- retaining ions
What problems do marine fish experience with maintaining water balance/equilibrium?
- more solutes on outside
- water constantly leaves
- retaining water
*to combat desecration
How do marine fish combat their challenge?
they drink the saltwater and excrete salt from gills/ specialized kidneys
*requires energy
(drink water to pump out ions)
How do freshwater fish combat their challenge?
- They remove excess water through urine to not lose solutes
- active uptake through gills
- keep selective dissolved ions in kidney
What is active uptake?
Using energy to take in ions through gills
What is concentration gradient?
How do we determine the energy required to move water against a concentration gradient?
the function of how great the concentration difference from outside to inside is
What are fish constantly trying to do?
maintain an internal solute concentration similar to their surroundings
why do fish match their internal solute concentration to their surroundings?
to not use as much energy
Which fishes are good at matching their internal solute concentration with their surroundings? What do they do?
- cartilaginous fish: sharks and rays
- raise osmotic potential of blood by retaining urea
What is osmotic potential?
what is urea?
- waste product
- nitrogen
What are salmon a good example of? How do they do it?
- organisms that move from the marine to the freshwater realm
- shift physiology
What do salmon do in freshwater?
cells begin to take in water triggering fish to stop drinking and kidneys kick in to produce urine with its pump switching direction
What do salmon do in marine environments?
chloride cells on gills excrete salt by actively pumping sodium and chloride across gills into seawater (against their concentration gradient
What do salmon do to acclimate?
move into the mouth of a stream where the brackish water is for a few days to activate enzymes
How do terrestrial animals eliminate excess salt?
drink lots of water
What do animals in drier climates do to eliminate excess salt?
Mammals: produce concentrated urine to not lose excess water
birds and reptiles: salt glands actively excrete salt
What does the lepidochora beetle do to obtain water?
these bettles go to a dune crest and, while facing the fog-laden wind, tip their abdomen upward where the grooves there collect the condensed water and move it toward their head
What are the two ways a beetle gains moisture?
- fog main source of moisture
- through food
what is metabolic water?
- cellular/aerobic respiration produces water
- moisture from oxidizing carbohydrates
kangaroo rat water budget
- large intestines reabsorb
- condenses water in nasal cavities
- at night feeding
- no sweating
- concentrated urine
camel water budget
- metabolic water
- concentrated urine
- their temperature can go up by 7* (vapor pressure deficit: matching to limit loss)
- can dehydrate blood
- can lose body weight in water
what color do plants use in photosynthesis?
blue
solar radiation and PAR
45%
photon flux density
the number of photons hitting a unit area per second
photon
smallest package of light
photon flux density variability
time of day, latitude, amount of cloud cover, north/south slope effect, season, shading
carbon fixation
into biomass
C3 plant photosynthesis
- dominate
- mesophyll cells
- ## RuBP combines with CO2 to form C3
- need to keep stomata open
- Rubisco enzyme has low affinity of combing with CO2 (combines with oxygen instead)
- came first
what is the problem with keeping stomata open?
lose water easily
C4 plant photosynthesis
- mesophyll cell & bundle sheath cells
CO2 diffuse with mesophyll cell to combine with PEP to produce C4 - catalyzed by Pepco
- C4 diffuses into bundle sheath cells
- breaks down and forms CO2 again
- then C3 processes again
Pepco
-higher affinity for carbon
- don’t have to open stomata so much and don’t need so many
- moves fasters
CAM plant photosynthesis
- close stomata during the day
- stomata open at night
- carbon fixation at night
- CO2 into mesophyll, catalyzed with pepco to make C4
- breaks down C4 in day to produce CO2
- C3 process
- slow
- water efficient
Comparing C3, C4, CAM
- C4 chloroplasts: in bundle sheath cells
- CAM plants have large vacuoles in mesophylls
- enznyme fix: Rubisco, Pepco, Pepco
- optimum temp: 15-25, 30-40,
- water efficiency:
vacuoles
store stuff
where can we find C4 plants?
near mexico, florida, southwest
what is potential evaporation __
what are the costs of C4 photosynthesis?
- don’t generate as much energy per CO2
- 2 ATP for every
- can’t handle water stress
what is the rate a plant can take in energy?
limited
tubeworms
- symbiotic relationship with tissue bacteria
- red:
where can you find chemoautotrophic bacteria?
- nitrifying bacteria in soils and aquatic environments
what is nitrification?
what are the heterotrophs?
what is most biomass made of?
C, O, H, N, P
what limits growth? why?
nitrogen because it is needed to make DNA, RNA, and proteins
what is C:N ratio?
ants and acacias
what are tannins?
in black coffee
tropical plants and defenses
mustard oils, alkaloids, cardiac glycosides, capsaicin
cellulose
not digestible by any animal (only bacteria)
What are saline wetlands referred to as?
wet deserts
What do plants do to make water enter cells?
- they increase their internal solute concentration with NaCl or other solutes
- this causes the plant’s solute concentration to exceed the surroundings
How do halophytes avoid/tolerate high salt levels?
- exclusion
- Secretion
- Succulence
What is damaging to most plants?
increased internal solute concentrations (NaCl)
