Transport in Plants Flashcards
What is transpiration?
Transpiration is the movement of water from the roots to the leaves through the xylem and then the loss of water by evaporation
What is transpiration stream?
passage of water and minerals through the roots, stem and leaves of a plant
The loss of water vapour from plant leaves by ——— of water at the surfaces of the ——-cells followed by ——of water vapour through the ——-
The loss of water vapour from plant leaves by evaporation of water at the surfaces of the mesophyll cells followed by diffusion of water vapour through the stomata
Xylem is adapted in many ways
mention 3
- A substance called lignin is deposited in the cell walls which causes the xylem cells to die
- These cells then become hollow (as they lose all their organelles and cytoplasm) and join end-to-end to form a continuous tube for water and mineral ions to travel through from the roots
- Lignin strengthens the plant to help it withstand the pressure of the water movement.
What is lignin and whtat is its function?
Lignin is a woody material present in the cell walls of xylem vessels it provides strength and makes the walls withstand the pressure of the water movement, anlso makes the walls impermeable to water
Movement in xylem only takes place in one direction - from roots to leaves (unlike phloem where movement takes place in different directions)
true or fales
true
in the xylem structure there is no internal cell walls
true or fales
true
choose the correct answer
movement of water
surface of mesophyll to air spaces is by evaporation / diffusion ?
and leaves the stomata by evaporation / diffusion ?
movement of water
surface of mesophyll air spaces is by evaporation
H2O (l) —-> H2O(g)
and leaves the stomata by diffusion
Transpiration has several functions in plants:
list 4
- transporting mineral ions
- providing water to keep cells turgid.
- providing water to leaf cells for photosynthesis
- keeping the leaves cool
How does Transpiration Occur?
evaporation of water from the leaf cell walls into air spaces in spongy mesophyll.
followed by diffusion of water vapour out of the leaf through stomata
How is the Transpiration Stream Created?
- Water molecules are attracted to each other by cohesion - creating a continuous column of water up the plant
- Water moves through the xylem vessels in a continuous transpiration stream from roots to leaves via the stem
- Transpiration produces a tension or ‘pull’ on the water in the xylem vessels by the leaves
- As water molecules are held together by cohesive forces (each individual molecule ‘pulls’ on the one below it), so water is pulled up through the plant
- If the rate of transpiration from the leaves increases, water molecules are pulled up the xylem vessels quicker
where does the transpiration stream happens in plants?
xylem
phloem cells are living cells
and xylem has dead cells
true or false
true
what does have a higher water potential?
pure water
solution?
pure water?
define the term osmosis
net diffusion of water molecules accross a partially permeable membrane from from a solution with a high water potential to a solution with a low water potential.
when does the plant cell become flaccid?
if put in dilue solution ?
if put in concentrated solution?
if put in concentrated solution
when does the plant cell become turgid?
if put in dilue solution ?
if put in concentrated solution?
if put in dilue solution
define the term turgid
description of a plant cell with a high internal pressure so that the cytoplasm pushes against the cell wall.
explan what happnes to the plant cell if it’s plasmolysed.
a plant cell that has lost water by osmosis. this is resulting in the cell contents shrinking and the cell membrane and cytoplasm pulling away from the cell wall.
a plant cell was placed in a concentrated sucrose solution. the diagram below shows the appearance of the cell after an hour in the solution
what is the best description of this cell?
- turgid
- flaccid
- plasmolysed
- wilted
plasmolysed
differentiate between the following
evaporation , traspiration
what are the factors affecting the rate of diffusion?