Unit 3 - Sonoran Intro, Water Transport & RGR/WUE Flashcards
What are examples of structure and function in this unit?
structure: leaves/plants/communities/ecosystems
function: photosynthesis, energy allocation, biodiversity
Where is water the most stressful in the US?
Southwest
In what two main ways does the distribution of precipitation change?
(1) spatially - WHERE
(2) temporally - WHEN
Does rain become more/less frequent & more/less intense with climate change?
less frequent; more intense
What happens with rain storms with climate change?
more floods and droughts
Is there more or less snow with climate change?
less
What is the difference between global average and flat areas with regards to species migration?
flat areas tend to be higher because animals/plants have to move way further than if mountains were available; its harder to move poleward than up
For every 1 degree C increase in average temperature, how far must a tree migrate upward compared to poleward?
upward: 175 m
poleward: 103 to 145 km (much larger distance)
What is the relationship between RCP and migration speed?
direct; higher RCP = higher migration to keep up with envelopes
Under which RCP emissions scenario would most plants be fine?
RCP 2.6
What are two options to help species that can’t keep up with their envelopes?
(1) let “nature” take its course - some species will migrate fast & others won’t
(2) step in to help plants and animals move faster - ASSISTED MIGRATION
definition: move plants and animals to places where we think they will be able to survive in the future to “speed up” their migration
assisted migration
What is currently happening with climate change (temperature) in the Sonoran Desert?
temperature is going UP
What is currently happening with climate change (rainfall) in the Sonoran Desert?
rainfall is going DOWN
What are some pros of assisted migration?
-increase/maintain biodiversity
-prevents extinction of species
-prevent negative ripple effects to a food chain
-ecosystem services
What are some cons of assisted migration?
-may put organism in the wrong spot
-genetic/bottleneck effect
-organism may not have proper resources in new location
-competition
-invasive species
-proper timing of move
What is the baseline for converting degrees C to F?
25 C = 75 F
How do temperature and rainfall change throughout the year in the Sonoran desert?
both fluctuate
high temps: may-september
high rainfall: jan-mar, July-august
What are the wettest months in the Sonoran Desert?
march and august
What are the driest months in the Sonoran Desert?
June
What is the problem with growing plants in the summer and spring?
summer: although it might be wet enough, it is too hot 95 degrees F and will evaporate immediately
spring: too dry/little rainfall
When is the best growing season for plants in the SD, especially annuals?
winter
What is the type of plant that grows, sets seed, and dies in a single growing season?
annual
What are the 3 main species we study that survive extremes in the SD?
(1) saguaro cactus (perennial)
(2) wildflower (annual)
(3) mesquite shrub (perennial)
How much of the Earth’s biomass do plants make up? Bacteria? Fungus? Animals? Archae?
plants: 80%
bacteria: 13%
fungus: 2%
animals: 0.36%
Archaea: 1.3%
How much of the Earth’s biomass do humans make up?
0.01%
What molecule (not atom) makes up most of a plant’s biomass?
cellulose
What is the molecule that makes up cell walls, is a carbohydrate, & made from the sugar that is a product of photosynthesis?
cellulose
Where does the C in cellulose in a plant come from, air or soil?
air
What can prove that plants get their C from the air?
Van Helmont’s Experiment (1600s)
Describe the basics of Van Helmont’s experiment.
(1) weighed out 200 lbs of dirt & planted a 5 lb tree in it for 5 years
(2) What happened to the soil? BARELY changed; 200 lbs–>199lbs
(3) What happened to the weight of willow tree? grew massively; 5 lbs–> 169 lbs (but it didn’t get its biomass from the soil so must have gotten it some other way – air!)
What makes up the shoot system of a plant? Root system?
shoot: flower, leaf, fruit, stem
root: root
What plant organ obtains water?
roots
What plant organ creates or obtains Carbon/sugar?
leaf
What plant organ collects light?
leaf
If you want to be able to grow fast (cellulose needed), where should you allocate all of your resources?
LEAVES
If its dry, where do you want to allocate your resources?
roots (need water to be absorbed from soil)
Why is water important for plants? (2 reasons)
(1) photosynthesis reactant
(2) plant structure
definition: created when the vacuole, full of water, exerts outward pressure on the cell wall
turgor pressure
When vacuoles are full of water, what is turgor pressure like?
very high
When vacuoles are lacking water, what is turgor pressure like?
very low
A rigid plant is described as _____ and wilted plant as ______.
turgid; flaccid
In a ____ cell, water flows into cell by osmosis and makes the vacuole swell & push against the cell wall.
turgid
What is the concentration of solute and solvent like INSIDE a turgid cell?
solute: high
solvent (H2O): low
In a ____ cell, water flows out of the cell & the vacuole shrinks, making the cell lose shape.
flaccid
What is the basic reaction for photosynthesis?
CO2 + water + light/ATP –> Glucose (sugar) + O2
What two characteristics of water help a plant to stand up?
(1) turgor pressure
(2) osmosis
What is the concentration of solute and solvent like INSIDE a flaccid cell?
solute: low
solvent: high
______: the diffusion of water
osmosis
_____: the passive movement of molecules from high to low concentration to establish an equilibrium
diffusion
OSMOSIS-movement of WATER molecules from _____ to ______ water concentration.
high to low
What type of membrane does osmosis take place across?
semipermeable (only water moves)
What are similarities between diffusion and osmosis?
movement from high to low concentration
What is unique to diffusion?
-BOTH solute and solvent move
-movement of molecules
-doesn’t involve energy/ATP
What is unique to osmosis?
-ONLY solvent moves (most likely water)
-semipermeable membrane involved
-focuses on concentration of water
definition: a process by which water molecules pass through a semipermeable membrane from a less concentrated solution (more dilute) into a more concentrated one, thus equalizing concentration on each side of the membrane
osmosis
Water concentration moves from high to low or from ____ to highly _____ solutions.
dilute; concentrated
Where does water enter a plant? Where does it leave?
enter: roots
leave: leaves (stomata)
How does a redwood move thousands of gallons of water up to its leaves EVERYDAY?
by using its transport system containing the vascular tissues Xylem and Phloem
Why do leaves need water?
for photosynthesis
What specific vascular tissue carries dissolved nutrients, hormones, sugars, etc. around a plant in any direction - using osmosis?
Phloem
What specific vascular tissue carries water through hollow “dead” cells from roots to leaves ONLY?
Xylem
Xylem is one _____ and water only flows ___.
directional; UP
Xylem Tissue participates in _____ water transport using what 2 processes?
passive; cohesion & adhesion
definition: process where water molecules stick to other water molecules (Hydrogen bonds)
cohesion
definition: process where water sticks to other molecules, such as cellulose
adhesion
What are Hydrogen bonds?
partially positive charged H that is attracted to partially negative charges of O
What type of bonds facilitation adhesion and cohesion?
H bonds
Does the xylem extend into the leaves of a plant?
yes
Where does water become water vapor?
in the spaces between guard cells (stoma)
Why does water need to become water vapor?
so it can enter cells for photosynthesis
Once water moves up plant, what fills spaces in leaves and why?
water vapor; so photosynthesis can access it
On what side of a leaf are stomata normally found?
underside
Water and sugar transport in the vein includes what type of tissue?
vascular
What happens every time water escapes from stomata?
negative pressure is created
What is responsible for water moving UP from the roots to the leaves of a plant through the XYLEM?
pulling up creates NEGATIVE pressure, forcing water to move up tree where there is low pressure
What word/process is Phloem mainly associated with?
osmosis
What word/process is Xylem mainly associated with?
negative pressure
What are the gaps that open and close and allow gases to enter and exit leaves?
stomata
What gases do plants need?
CO2 (carbon dioxide)
What gases do plants need to get rid of?
Oxygen (O2)
Why do plants need to get rid of Oxygen?
Oxygen in high concentrations in leaves is toxic
What is the constant gas exchange?
CO2 always coming in (photosynthesis) & O2 always going out
Why is constant gas exchange ideal?
CO2 needs to come in for photosynthesis to take place and O2 needs to leave before it builds up to be toxic
What is the tradeoff of gas exchange in stomata?
water vapor loss for CO2/O2 gas exchange
When is the tradeoff of gas exchange not a problem anymore?
when water is plentiful
Under what conditions are stomata open?
when water is abundant (guard cells turgid)
Under what conditions are stomata closed?
when water is scarce (guard cells flaccid)
What is an automatic way for plants to stop water loss?
close their stomata (stops gas exchange)
When does the stomata gap start to seal up?
as soon as cells start to lose turgor pressure, deflate, and lose water
What will happen to stomata if there is an unlimited supply of water for a plant?
they will stay open and not worry about the tradeoff from gas exchange
What would happen if stomata never opened?
no photosynthesis would take place & there would be O2 toxicity; this is why plants grow slower when its dry (but more water conserved)
What is another way to open and close stomata?
forcing stomata to open using hormones and ion flow
If plants risk growing fast by undergoing lots of gas exchange, what might happen?
they might run out of water
If plants risk growing slow with little gas exchange, what might happen?
they might get out-competed by faster growing plants
What does the rate of H2O loss from a leaf depend on?
how fast water transpires depends on the gradient
Does water always escape at the same rate from a leaf?
no, it depends on the gradient
Does a smaller gradient (smaller difference between two environments), lead to slower or faster diffusion?
slower diffusion (ex: when air outside is humid)
Does a larger gradient (large difference between inside & outside environments), lead to slower or faster diffusion?
faster diffusion (ex: when air outside is dry)
What does the rate of water loss depend on?
depends on outside environment & the gradient
What does the rate of H2O loss from stomata depend on?
the difference in gradients inside and outside
Larger gradient = ______ diffusion. Smaller gradient = _______ diffusion.
faster; slower
What is the main gas that enters a stomata? Exits?
enters: CO2
exits: water vapor and O2
Under what environmental conditions will a plant wilt faster? (think weather conditions - if you need to dry your clothes quickly, what conditions would speed that up)
-higher temperature
-more wind
-low humidity
-high surface area
What are 4 factors affecting the rate of evaporation?
(1) temperature
(2) wind
(3) surface area (# of stomata or leaf area)
(4) humidity
definition: evaporation from plants
transpiration
How does increased temperature speed up water loss?
higher rates of evaporation
How does increased wind speed up water loss?
-water vapor escaping a leaf can form a boundary layer of humid air around the leaf if no wind is present (smaller gradient & slower diffusion)
-a windy day will blow water vapor away from the leaf replacing it with new, dry air (larger gradient = faster diffusion)
How does low humidity speed up water loss?
-more water vapor in hot air
-with low humidity, there is faster transpiration due to a larger gradient
How does increased surface area speed up water loss?
more leaf area = more stomata = faster/more ways to lose water
How does the total amount of water transpired from a plant differ from the rate of H2O loss?
total amount of water transpired depends on the amount of TIME stomata are open and the rate of H2O loss
Describe a scenario in plants that would transpire the most amount of water:
-a hot, dry, windy day
-wet soil–> if plants have access to water in the soil, this will ensure that stomata stay open (high turgor pressure)
In normal conditions, an increase in photosynthetic rate is correlated with which of the following?
(a) reduced transpiration
(b) lower glucose production
(c) more plant growth
(d) more CO2 production
(c) more plant growth because the more glucose produced = more food = increased growth
-if there is lots of photosynthesis going on, this means that stomata are open so there is increased transpiration
How are photosynthetic and transpiration rates related?
directly
Maximum photosynthetic rate for a plant ca n be (directly) increased by increasing what?
(a) root production
(b) leaf area
(c) height
(d) seed production
(b) leaf area
Even though high leaf area means high maximum photosynthetic rate and high maximum growth rate as a result, what is the drawback of having high leaf area?
high transpiration = bigger leaves = more stomata = plenty of water loss
Do plants in the Sonora desert likely have large or small leaf area?
small leaves & fewer leaves overall to limit water loss from stomata
definition: live their whole lifecycle from seed to seed in one year
annuals
How can winter annuals survive living in a place that gets so little rain, so infrequently?
(1) when it does rain, grow really fast & hope you don’t dry out before you produce seeds
(2) limit how much water you lose and try to get through your lifecycle slowly, but steadily
What are the two main strategies & goals winter annuals use to survive in the desert?
(1) growing really fast when it rains (goal: to produce seeds)
(2) conserve water and grow slowly (goal: to survive)
What two things allow us to measure the tradeoff between the 2 strategies winter annuals use>
(1) relative growth rate (RGR)
(2) water-use efficiency (WUE)
What term represents biomass gained / time?
relative growth rate (RGR)
What term represents carbon gained (growth) / water lost?
water use efficiency (WUE)
Describe the analogy for the Sonoran Desert.
Prius vs Porsche
-both run and consume gas, but one is built for speed and the other is built for fuel conservation–has to do with how engine is built
High WUE vs High RGR
-both grow and both will lose water, but one is built for speed and the other is for water conservation (MPG = WUE)
What type of species is really efficient at growing with only a little bit of water (high/low WUE)?
High WUE
_____ WUE conserves water and ____ WUE loses water quickly.
high; low
Why can’t you be high in both RGR and WUE?
what gives a plants high RGR –> lots of large leaves leaves (because of photosynthesis) leads to lower water conservation (low WUE)
What gives a plant high RGR?
leaves! leaves maximize photosynthetic area = more sugar = more cellulose = more growth
What will lots of leaves mean for conservation of water?
BAD –> large leaves = lots of stomata = more water loss
How are WUE and RGR related?
inversely related
Do all winter annuals have similar WUE?
no, they vary between low–> high WUE
What does the negative relationship between WUE and RGR ultimately suggest?
fast growers = water wasters
slow growers = water conservers
What car in the analogy has high RGR but low WUE?
porsche
What car in analogy has low RGR but high WUE?
Prius
What is the tradeoff with RGR and WUE?
rapid growth vs. drought tolerance
What is the relationship between RGR and leaf area ratio (leaf area / plant biomass)?
positive/direct
Describe winter precipitation in the Sonoran Desert:
-varies interannually
-very unpredictable
-some years really dry and some really wet
What is the major result of winter precipitation being so variable and unpredictable in the Sonoran desert?
drastic shifts in plant growth ad established plant species from year to year
Describe rainfall events by SIZE in the Sonora Desert.
-large rain events (storms)–> quite rare
-small rain events (<2mm rain)–> quite frequent
______ rainfall event: a little rain, soil dries fairly quick, but another one might be around soon.
small
_____ rainfall event: soil stays wet for longer so there’s more water around all at once to be taken advantage of.
large
What species high WUE or RGR thrives in small rainfall events? Why?
high WUE - these plants capable of conserving water can just grow a little bit and then wait for the next rainfall event
What species high WUE or RGR thrives more in large rainfall events? Why?
high RGR - can use water and grow as tall as they need before all the water runs out even though they aren’t conserving water particularly well
Does high RGR species show more carbon gain & plant growth in small or large rainfall events?
large
Does high WUE species show more carbon gain & plant growth in small or large rainfall events?
large
What plant species type will win most of the time with regards to rainfall events?
high WUE species because smaller rain events are much more common
What kinds of weather will favor high WUE vs high RGR species?
small rain events: high WUE
large rain events: high RGR
Which type of species (high WUE or high RGR) will experience more variation in population size/growth from year to year? Why?
high RGR because they rely on large rain events which are infrequent and unpredictable
Is one strategy always best with RGR and WUE?
no, there are years where high RGR species have high fitness, High WUE species have high fitness, where all plants do poorly, and where all plants do well
What determines a winner from year to year?
higher fitness = more offspring/seeds
When there is so little water, how do so many species persist in the Sonoran (How is biodiversity so high?)
environmental variability
How does environmental variability lead to high biodiversity in SD?
change in environment from year to year results in different species surviving at different times
