Transport in plants Flashcards
Suggest two advantages of chloroplast movement within palisade cells
to absorb more light
to avoid damage from high light intensities
Xylem function
-Structural support
- Food storage
- Carries dissolved minerals & water up the plant
Phloem function
Transport organic compounds (esp. sucrose) from the source (eg leaf) to the sink (eg root)
Which way does phloem transport organic compounds
Up and down the plant
What complex cells are the phloem made up of?
and state 2 of their role
-Sieve tube elements (main conducting cells)
- Companion cells
- Parenchyma (storage and strengthening of the fibres)
What are the structures in xylem elements
- Lignified cell walls
- No end plates
- No protoplasm
- Pits in wall
- Small diameter in vessels
Hows does lignified cell walls help xylem
-Adds strength to withstand hyrdostatic pressure
- Impermeable to water
How does no end plates help xylem
Allows mass flow of water & dissolved solutes as cohesive and adhesive forces are not impeded
How does no end plates help xylem
Allows mass flow of water & dissolved solutes as cohesive and adhesive forces are not impeded
how does No protoplasm help xylem
doesnt impede the mass flow of water and dissolved solutes
how does pits in walls help xylem
allows continuous flow even if air bubbles formed in vessels
how does small diameter of vessels help xylem
-Prevents water column from breaking
-Assists capillary action
State the structures of the sieve tube elements in phloem
- Sieve plates with sieve pores
-Cellulose cell wall
-No nucleus, vacuole, or ribosome in mature cells
*Er and mitochondria is present
-Thin cytoplasm
Function of sieve plates and sieve pores in phloem
Allows for continuous movement of the organic compounds
Function of cellulose cell wall in phloem
Strengthens the wall to withstand hyrdostatic pressure that moves the assimilates
Function of having no nucleus, vacuole or ribosomes in phloem
Maximizes space for translocation
Function of thin cytoplasm in phloem
Reduces friction to help movement of assimilates
What does companion cells do in plhoem?
- They control the metabolism of their associated sieve tube member
- They help in unloading and loading sugars into the phloem
Function of nucleus and other organelles in companion cells?
-Provides metabolic support to sieve tube elements
-Helps in the loading and unloading of assimilates
Function of transport proteins in plasma membrane located in the companion cells?
Moves assimilates in and out of the sieve tube elements
Function of large no. of mitochondria in companion cells?
Provides ATP for the active transport of assimilated in and out of the companion cells
Function of plasmodesmata in companion cells?
It links the sieve tube elements, allowing organic compounds to move from the companion cells into the sieve tube elements
What is the liquid transported in phloem sieve tubes called?
Phloem sap
Outline the role of ATP in leaf cell
It provides energy ( don’t write produces)
- for active transport of sucrose from source to sink ( proton pumping H+ ions)
- for endocytosis ( movement of vesicles)
Explain how hydrogen bonds occur between water molecules
- weak hydrogen bonds present
- water is dipolar
- oxygen has a SMALL negative charge and hydrogen has a SMALL positive charge
Why is water an excellent solvent for ions
- Water is polar
- ions are charged
- therefore there will be an attraction between ions and water molecules
