7.1 Structure of transport tissues Flashcards
Plants need transport systems to meet their ___ ___
eg: ___
metabolic demands
eg: glucose, hormones, mineral ions
Plants consist many layers of cells so cannot rely on ___ for this would be ___
diffusion , slow
Plants have a ___ ___ which involves a network of vessels running through ___, ___, and ___.
vascular system, leaves, stem, roots
Vascular system (2) How are they arranged?
Xylem , Phloem
are arranged together in vascular bundles
Leaf structure (8)
Vascular bundles, upper epidermis, palisade mesophyll , lower epidermis , phloem , xylem , spongy mesophyll
Stem Structure (7)
Vascular bundle, epidermis, cortex, phloem, xylem, cambium, pith
Root Structure (6)
epidermis, phloem, xylem, cortex, endodermis
Xylem and Phloem locations in the leaf
Xylem: upper
Phloem: lower
Xylem and Phloem location in the stem
Xylem: inner
Phloem: outer
Xylem and Phloem location in the root
Xylem: cross
Phloem: the rest
Xylem function (3)
- vascular tissue that carries dissolved minerals and water up the plant
- Structural support
- Food storage
Location of the vascular bundle and why? –Xylem roots (3)
center core, helps the roots withstand the pulling strains as the plant transports water upwards and grows
Location of the vascular bundle and why? –Xylem stem (3)
vascular bundle are located outside, the xylem tissue is found on the inside – closest to the center of the stem to help support the plant
Location of the vascular bundle? –Xylem leaf (3)
Form the midrib and veins – spread from the center of the leaf, Xylem is found on the upper side (closest to the upper epidermis)
Function of the phloem (2)
- Transport organic compounds
eg: sucrose
from the source to the sink –> these can occur up and down
Phloem structure
Complex tissue – bulk made up of sieve tube elements (main conducting cells) – companion cells
Location of the vascular bundle? –Phloem roots (2)
center core, on the edges of the center core
Location of the vascular bundle ? – Phloem stems (2)
Located outside and phloem is found on the outside
Location of the vascular bundle? – Phloem leaves (3)
form the midrib and veins – spread from the center phloem tissue found on the lower side of the bundles
Function of Lignified cell walls (xylem)
adds strength to withstand hydrostatic pressure so vessels do not collapse
No end plates function (xylem)
allows the mass flow of water and dissolved solutes as cohesive and adhesive forces are not delayed
Cohesive(xylem)
between water molecules
adhesive(xylem)
between water molecules and xylem wall
No protoplasm – cells are dead when mature function (xylem)
does not delay the mass flow of water and dissolved solutes
Pits in walls (in non-lignified section) function (xylem)
lateral movement of water allows for continuous flow in case of air bubbles forming in the vessel
The small diameter of vessels function (xylem)
helps prevent the water column from breaking
Structure in xylem vessel (5)
- Lignified cell walls
- no end plates
- no protoplasm (cells are dead when they mature)
- pits in walls (in non-lignified sections)
- Small diameter of vessels
Phloem sieve tube elements structures (4)
- sieve plates with sieve pores
- cellulose cell wall
- no nucleus, ribosomes, or vacuole
- thin cytoplasm
Phloem structure: sieve plates with sieve pores – function
allows for continuous movement of organic substances
Phloem Structure: cellulose cell wall – function
strengthens the wall to withstand the hydrostatic pressures that move assimilates
Phloem Structure: no nucleus, ribosomes or vacuole in mature cells – function
maximizes space for movement of assimilates
Phloem structure: thin cytoplasm – function
reduces friction to facilitate movement of assimilates
Companion cells Phloem companion cell structure (4)
- nucleus and other organelles present
- transport proteins in plasma membranes
- age numbers of mitochondria
- plasmodesmata (channels in cell wall)
Xylem and Phloem’s key differences:
1. Living cells
2. Substances transported
3. process of transportation
4. diction of flow
5. presence of end walls
6. cell wall material
- X: no P: yes (companion cells)
- X: water and mineral ions P: organic compounds / assimilates
- X: transpiration P: Active translocation
- X: One way / upwards (roots –> leaves) P: two ways — up or down
- X: no P: yes (sieve plates)
- X: Lignin and cellulose P: cellulose
