Transport In Plants Flashcards
In what vessel does water travel through to reach the top of the plant
The Xylem vessel
What properties of water make it useful for transport in plants (5)
A good solvent
Polar so bonds or sticks to itself - cohesive
Adhesive - sticks to other things
High specific heat capacity
Water densest at 4 degrees so ice floats on top
What is the job if the cambium
The cambium is responsible for making new xylem and phloem and is found between existing ones.
What is the structure of vascular bundle
Found in outer edge of stems and are seperate in woody plants but become continuos in older stems.
This means there is a ring of vascular tissue under the bark of a tree. This offers support and flexibility.
What is the structure of young roots
At the centre is the vascular bundle and the central core is made of xylem. Phloem is between the arms and offers strength. Surrounding the vascular bundle is the endodermis. Meristem then forms layer called pericycle inside the epidermis.
What is the name of cells that can still divide
Meristem cells
What is the job of lignin
Waterproofs the cell causing it to die. The walls and contents then begin to decay. Strengthens walls to prevent it from collapsing.
What is the structure of xylem vessels.
Xylem vessels are long tube of dead cells with no end walks ( due to lignin )
What are 4 patterns in cell walls
Spiral
Anular
Peticulate
Pitted
What are the useful adaptions of xylem vessels that make it good for transporting water
Dead cells allighn to make continuos collumn
Pits allow movement of water
Lignin in walls allows xylem to grow and stretch and bend.
Flow of water not impeded as no end walls, nucleoles, cytoplasm.
What are the 3 paths water can take through cells
Symplast
Apoplast
Vacuolar
What is the apoplast pathway
Water moves between spaces between cells. Never enters cell as travels between cells
What is the symplast pathway
Water enters cytoplasm through plasma membrane. Then passes through holes (plasdodesmata) from one cell to the next. Cytoplasm in plasmodesmata ensures that it is continuos between cells.
What is the vacuolar pathway
Similar to symplast but water not confined to cytoplasm and can pass through vacuole as well.
What prevents water from entering xylem through apoplast pathway.
The casparian strip
How do nitrate ions pass into xylem
They are actively transported from the cytoplasm of cortex cell to the xylem.
By what process does water enter the xylem
Osmosis
Water potential in xylem low
What surrounds the xylem and phloem and has the casparian strip
The endodermis
What are plants that are adapted to living in very dry or arid conditions called
Xerophytes
What is translocation - brief description
Movement of assimilates (sugers and other chemicals made by plant cells).
What is a source in terms of sucrose
Part of plant that releases sucrose into the phloem
What is a sink in terms of sucrose
Part if plants that removes sucrose from phloem
What form do sugers take when being transported in phloem
Sucrose
What are companion cells
Thin cells to the side of sieve tube elements
