3.3 Plant Transport Flashcards
Define herbaceous
Non-woody stem
Define dicotyledonous
Plants with two seed leaves and a branching pattern of veins in the leaf
Define transpiration
The loss of water vapour from the ariel parts of the plant via the stomata
Role of transpiration
Transports mineral ions
Maintains cell turgidity
Supplies water for growth, elongation and photosynthesis
Keeps the plant cool
Factors effecting transpiration
Light intensity, temperature, humidity, wind, water availability
How to assemble a potometer
Assemble underwater
Cut stem underwater
Cut stem angle
Dry leaves
Describe transport of water in the plant
Water moves into root hair cells by osmosis
Water gets to xylem via symplast (cytoplasm) or apoplast (cell wall) pathway until it reaches impermeable casparian strip.
Water moves up xylem vessel via tension, cohesion and adhesion
Why does water enter root hairs by osmosis?
Soil always has a higher water potential than root hairs as water is constantly lost by transpiration
What is tension, cohesion and adhesion
Tension: sucking force caused by water evaporation
Cohesion: water molecules stick together
Adhesion: water molecules stick to xylem wall
What are xerophytes and how are they adapted?
Plants adapted to living in dry conditions
Waxy cuticle, sunken stomata, hair, spines, rolled leaves, close stomata
What are hydrophytes and how are they adapted?
Live in water (less O2 e.g. Lillie’s)
Stomata on upper surface, air spaces (buoyancy + store O2 for aerobic respiration), Supported by surrounding water, flexible leaves and stems to prevent damage from water currents
Describe the mechanism of translocation
Active transport of H+ ions
Cotransport of H+ and sucrose
Sucrose diffuses into sieve tube lowering water potential
Water enters sieve tube from xylem by osmosis generating hydrostatic pressure gradient
Solute moves from source to sink by mass flow
