3.3.4.2 mass transport in plants Flashcards
Adaptation of a root hair cell
Large surface area to volume ratio
Absorb of water from the soil to plant
Osmosis from high water potential to lower the potential area
High density of mitochondria and carrier protein : ATP need for active transport
Use of water (how is this related to assumption of potometer experiment)
Fill up vacuole , leaf cell turgidity
Photosynthesis
Medium to transfer mineral ions
Hydrolysis to put down small molecules
It’s not valid to assume that water uptake what is equivalent to the rate of transpiration?
Definition of transpiration
Evaporation of water from the leaves of plants via stomata
How episode of absorption in the route to continue?
What are potential of soil is higher than the water move into the cell and sell water potential increase so is higher than the next cell so process continue.
Factor that affects evaporation rate
Humidity
Higher humidity, shallow water, potential gradient, less net movement of water from leave to air , lower evaporation rate
Wind : higher windspeed, maintain water, potential gradient due to constantly remove water on, leave surface and water vapour/ moisture air, higher evaporation rate
Temperature : higher temperature, more kinetic energy, move faster water, molecules move, diffuser move further, apart from each other, change from liquid to gas increase, evaporation rate
Light intensity: increase in light intensity, more stomata open, so increase in flow rate due to cohesion of water molecules
Hey, what causes water to move up the xylem?
Transpiration stream(pulling force)
Water are is dipolar with negative oxygen and and positive hydrogen and attract each other
Hydrogen bonds between molecules (cohesive)
Attraction with wall of xylem (adhesive)
Transpiration (evaporation from the stomata on leave)
Lower water, potential in cell
Create negative pulling pressure
Water pull up as column
Capillary action
Narrower tube , surface area to volume ratio increased, more adhesive force, more pulling force
Root pressure (pushing force) from leaves cell to xylem
Structure of xylem related to the function
Long, continuous, hollow tube: continuous column of water pull up, maintain transpiration stream, quick easy, water flow
No end wall/ no organelle : easy, waterflow, no obstruction
Lignin wall : withstand cohesion tension ,provide support and strength, prevent collapse
Pits in wall : allow lateral movement / get round block vessel
Use of poto meter
Measuring the rate of transpiration
How to measure the rate of transpiration (cm3 per min)
Measure the distance of water move
Measure the time
Measure the radius of capillary tooth
Distance divided by time
Precaution of the experiment, using potometer
Seal the bug tight and put Vaseline on plants
No air is allowed in , prevent water backflow to the reservoir by gravity, air bubble going back
Cut the stem in water
No air bubble lock , allow continuous water column with cohesion, prevent air bubble not moving
Dry leaves
No water blocks stomata to affect the rate of evaporation
No water bubble in apparatus
Accurate, volume calculation
How do you create different factor for transpiration experiment in Lab?
Wind, fan
Temperature , radiator
Humidity , plastic bag environment
Use of resourvoir in the experiment of potometer
Reset/ return the bubble back to the starting point
allow repeat
Increase reliability / anomalous, result, can be, identify
Definition of translocation
Transport of organic molecule room source (production) to sink (used/stored) via phloem
Structure and function of phloem
Rough, endoplasmic reticulum: produce carrier protein for active transport
Mitochondria : ATP for active transport against a concentration gradient
Plasmodesmata : allow cell to cell, transport and communication
Organelles pushed to the side/ at edge (no nucleus) (live) / few organelles/ more room : I easier and more flow
Sieve element + companion cell
Mass flow theory
Loading (active transport)
Transfer sucrose from photosynthesising cell (source) to sieve tube element (phloem) by companion cell
lower the water potential of sieve tube cell
So water enter by osmosis from source cell to sieve tube elements due to the creation of high hydrostatic pressure
Increase in pressure, cause mass movement toward sink
Mass flow : through sieve tube down at pressure gradient ( high to low hydrostatic pressure)
Unloading (active transport)
Sucrose out of phloem (sieve tube element to sink cell — respiration, convert for storage and growth )
Water move into xylem + sink cell , as the phloem have higher water potential when sucrose removed)