Multicellularity Flashcards
What is water required for (4)
Photosynthesis
Transport solutes
Cooling of plant
Structural support
Macro/micro nutrients needed for growth (3)
Iron (micro) → chlorophyll colour/enzyme/electron transport
Nitrogen (macro) → DNA/ATP/phospholipid
Phosphorus (macro) → small and stunted
Definition of water potential
tendency of solution to take up water from pure water through semi permeable membrane
Calculate water potential
Water potential = SP + PP
HIGH solute potential = ___ water potential
LOW
HIGH pressure potential = ___ water potential
HIGH
How does turgor pressure affect plant
Low turgor pressure = water moves into cell by osmosis (wilt/flaccid)
High turgor pressure = turgid
Direction of water flow
From (+) WP –> (-) WP
What is apoplast pathway
Water and solutes pass through cell walls - rapid and unregulated
What is symplast pathway
Water pass through plasmodesmata in cytoplasm - slow and regulated
Describe the water movement from root to vascular bundle
Water movement through roots by apoplast/symplast pathway
Water and solutes from apoplast → symplast
Water and solutes remain in symplast pathway
Solutes actively pumped into apoplast pathway
Water passively osmosis into apoplast pathway
What and where is the casparian strip
Roots in endodermis - blocks apoplast pathway
What is xylem made of
Vessel elements
Definition of transpiration
Loss of water by evaporation through the leaves
Steps of transpiration
During transpiration water diffuses out of the stomata
Water evaporates from mesophyll cell walls
Tension pull apoplast pathway
Pulls water in veins in to turn leaf outwards
Transpiration-cohesion-tension mechanism
(T) surface tension in apoplast of mesophyll cells - water pulled by adjacent cells into apoplast = negative pressure moves water out of cell
(C) tension pulls water up passively
(T) tension in stem cause water diffuse by osmosis into roots
Rank from lowest to highest water potential (soil/leaf/atmosphere)
soil > leaf > atmosphere
What is stomata activity regulated by (4)
light intensity
co2
temperature
water
Stomata activity in presence of light
Protons are pumped out Ions (K+/Cl-) enter water enters by osmosis increase turgor pressure open pore
Stomata activity in presence of NO light
Less active proton pump K+/Cl- diffuse out passively Water followed by osmosis Pressure goes down pore closes
How does light cause changes for stomata activity (light present)
Light activates photoreceptor Signalling cascade activates proton pump H+ pumped out of cell Electrochemical gradient cause K+ in Symport protein imports CL- and H+
Definition of translocation
Movement of carbohydrates/solutes through phloem = translocation
When do source and sinks change
Over seasons (carrot)
What are the phloem components
Sieve tube element cell
Companion cell
Sieve plate
Plasmodesmata
Why does the phloem need companion cell
cell lacks ribosomes/nucleus/golgi/cytoskeleton
Describe the mass flow through phloem
Sucrose actively transported from companion cell → sieve tube cell
Sucrose accumulate = WP lowers = high water potential to low water potential movement by osmosis
Increase in pressure
Sucrose active transport into sink cell cause increase in WP in sieve tube element
Water leaves phloem by osmosis
What does removing the bark of tree affect
phloem transport
