Transport in plants and structure of vessels Flashcards
what is a phloem
a tissue used to transport assimilates
What is a xylem
a tissue used to transport water and minerals
Why do plants need a transport system
to meet their high metabolic demand for o2, water, minerals etc..
to compensate for their small sa: vol ratio (large plants)
plants cant rely on diffusion alone.
What direction does water and minerals travel in the xylem
Upwards
What direction do assimilates travel in the Phloem
Up and Downwards
What is a dicotyledonous plant
plants with two seed leaves and branching veins in leaf
what two types of tissue also give strength to the vascular bundle
Collenchyma
Sclerenchyma
what is a tap root
the thick main root of a plant
what is the pericycle and what is it made of
The pericycle is a thin layer of plant tissue between the endodermis and phloem.
Made of meristem tissue
What is the function of the vascular cambium
Vascular cambium- pushes the xylem and phloem apart.
Name a b c and d
A- Collenchyma
B- Parenchyma
C- Vascular cambium
D-pith
What is the function of lignin in xylem
Impregnates the walls of the xylem, killing cells and making them waterproof
How does lignin cause long collums of xylem
Lignin kills the cells in the wall. The end walls and contents of cell begin to decay.
Causing a long column with dead cells and no contents.
How does lignin help the xylem to stay open
The lignin prevents xylem collapsing and keeps it open. Also provides flexibility to the stem/branch
What shape is lignin in the xylem
Spiral rings
or could be broken rings
How are bordered pits in the xylem formed
Lignification is incomplete. Leaving gaps in the cell wall making bordered pits.
What do bordered pits do (xylem)
Allow water to leave 1 vessel and pass into the next vessel
A xylem vessel can sometimes be paired with a “xylem parenchyma”, what are the two functions of this
- contain food stores to enable xylem to repair if necessary or grow
-contain tanin which is bitter, herbivores taste tanin and prevent herbivores eating plant
what direction does phloem move
source to the sink
what direction does water in xylem flow
upwards
why does the phloem transport sucrose rather than glucose
more stable form of sugar, not as easily used up
which vessel is alive? xylem or phloem
Phloem, to perform active transport in translocation.
what are the name of the individual segments of the phloem vessel
Sieve tube elements
what structure is interlinked to the side of a xylem
Companion cell