Summary
Summary Plant Physiology (NWI-BB069B)
- Course
- Institution
Summary of the lectures and lecture slides of plant physiology with pictures, drawings and transduction pathways.
[Show more]
Seller
Follow
lisavddries
Reviews received
Content preview
Plant physiology summaryL1 water & transport
Plants need water for:
- Firmness & growth
o More water -> more photosynthesis -> more primary production = CO2 fixation
- As a solvent
o Polarity: polar molecules dissolve
o H-bridges: adhesion & cohesion
- Transport
o Xylem = takes water + nutrients up
o Phloem = takes carbohydrates from production to use/storage, bidirectional
Need a lot: lose a lot via stomata during CO2 uptake
Change in homeostasis -> stress
Water potential = Ψw = potential energy of water, ability to perform work
Ψw = Ψs + Ψp + Ψg in Pa = J/m3 = N/m2
Osmotic + hydrostatic + gravitational
Osmotic potential = Ψs = - ∏ (osmotic pressure)
- Ψs = -(n/V) * R * T with n = particles , V = volume, R = 8.314, T = temp
- In plants < 0; in pure water = 0
- From hypotonic to hypertonic movement
- More dissolved particles -> higher, but negative -> lower
- Temp has only small effect
Hydrostatic pressure = Ψp
- From turgor = cell wall pressure: Ψp > 0
- From tension from cohesion of water in rising vessel: Ψp < 0
Gravitational potential = Ψg
- Ψg = pw * g * h with p = density, g = 9.81, h = height
- From position of water, mostly determined by height
- Always > 0, higher location, higher Ψg
- Only matters above +-10 m
Lower water potential -> water moves towards
Main driver is difference in Ψp between roots (uptake) and leaves (use)
Most water lost via evaporation: atmosphere has lower pressure -> diffusion
Elastic modulus = ε = elasticity of cell wall, depends on turgor pressure
- ε = ΔΨp/(ΔV/V)
- Higher -> more turgor
Transport inside cell: via diffusion, only short distances
Influenced by temp, distance and solvents
Water in/out cell: via aquaporins (= channels) + bit via bilipid layer, very slowly
Diffusion from leaf to atmosphere: via stomata
,Stomata opened or not determined by:
- CO2 concentration
- Ψw
Stomatal conductance = gs; leaf conductance = gl -> both decrease when stomata’s close
Guard cells in turgor -> open; guard cells not in turgor -> close
Other factors that influence evaporation:
- Humidity of atmosphere
- Temperature
- Wind
- Humidity of soil
- Light
Xylem
Vessels: angiosperms + some gymnosperms and ferns
Tracheids: gymnosperms, ferns and angiosperms
Both consist of dead cells (appoptosis), with reinforced cell walls (ligine)
More tracheids than vessels -> weaker wood. Vessels are thiner and stronger
Cavitation = water column in xylem breaks, air bubble = emboly
Water has to be pushed up from bottom = active process
- Active transport of ions to root xylem
- Ψs increases btwn cortex and vessel
- Transport of water to xylem
- Ψp increases
- Mass flow of water, decreasing the embolies
Guttation = droplets at end of leaves through hydathodes; water is pushed out
Water transport through cortex:
- Symplastic = via cytoplasm of cells
- Apoplastic = via cell walls
Transport into vessel always symplastic: Casparian strip in endodermis is impermeable to water
Clay contains more water available for uptake than sand:
more particles -> more water bound -> higher potential of soil
diural rhythm of water potential:
more water uptake during day, cause bigger
difference in potential
biggest difference in potential btwn:
leaf – outside and leaf cell – intercellular space
L2 nutrients
, Nutrient = building block that is taken up from soil,
determines bio-productivity together with water uptake
Yield-nutrient slope isn’t linear: doesn’t make much
difference after needed amount
Need for fertilizer is increasing in developing countries
But stocks of important nutrients are finite
Macronutrient = need a lot of it
N, K, Ca, Mg, P, S, Si
Micronutrient = only need a little bit -> still important, but toxic when too much
Cl, Fe, B, Mn, Na, Zn, Cu, Ni, Mo
Deficiency zone = too little
Adequate zone = enough
Toxic zone = too much
Nitrogen (N)
Large quantities
Used for: proteins, photosynthesis
o NH4 -> glutamate -> aa’s -> proteins
Available: NO3, NH4, or aa
o N2 fixation by bacteria/electrical sources: root nodules/rhizobium
o If taken up as NO3: NO3 -> NO2 -> NH3/NH4, but NO2 and NH3 toxic
o If taken up NH4: acidification of soil -> adaption
Uptake: with transporter proteins, NRT and AMT or ammonium passively
deficiency: chlorosis = no chlorophyll -> yellow leaves
o Only in bottom leaves, can reuse nitrogen
o + more lateral roots -> N in topsoil
Phosphorus (P)
Relatively high quantities (less than N)
Used for: nucleotides, ATP, phospholipids, sugars…
Available: inorganic molecules like HPO4, H2PO4
o Organic compounds need to be broken down before uptake
Uptake: transporter proteins, PHT
o Mycorrhiza help most plants get P
Deficiency: no ATP -> no transport -> accumulation of sugars and anthocyanin
o More lateral roots + roothair -> P in topsoil
o Smaller leaves, thin stems, old leaves die
Sulfur (S)
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller lisavddries. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.88. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
52510 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now