module 3 - 9.1 transport systems in plants Flashcards
why do plants need water?
- maintains turgidity of cells, stops wilting/ flaccidity
- used for photosynthesis
how do plants transport water up the stem?
transpiration - cohesion tension theory
what other substances do plants need?
- mineral ions (nitrates) to build amino acids
- glucose
- sulphur
- fertilisers (nitrate, phosphate, potassium)
why do metabolic demands require the need of a transport system?
plants are multicellular so require lots of energy for reactions
why does size require the need of a transport system?
plants need to move things over distances
why does SA:V require the need of a transport system?
- small SA as its multicellular
- root hair cells & leaves increase SA
why do plants need transport systems?
- larger plants don’t have a large enough SA:V to take in what they need
- they’ve developed specialised tissues for transporting water & nutrients to all cells
what are the plants called that have specialised transport systems?
vascular plants
what materials do plants exchange and transport?
- carbon dioxide
- oxygen
- water
- organic nutrients
- inorganic ions
what is photosynthesis?
plants producing glucose through sunlight
what is respiration?
plants supplying energy
what is active transport?
energy required to move/ transport substances
what are the two transport systems?
- transpiration systems
- translocation systems
what is the transpiration system?
- movement of water molecules & dissolved mineral ions
- passive process
- xylem vessels
- unidirectional
what is the translocation system?
- movement of sugars (sucrose) & amino acids
- active process
- phloem vessels
- bidirectional and seasonal
what is the vascular bundle?
- vascular tissue throughout the plant - made of xylem and phloem tissue
- vascular bundle can transport substances & has structural support
what is the vascular bundle like in the ROOTS?
- provides ‘drill’ like structure that enables plant to push down into roots
- xylem tissue is in the center - strongest (X structure)
- phloem in 4 sections
what type of cells are meristems and what do they form in the roots?
- undifferentiated cells
- form new xylem and phloem tissues
what is the vascular bundle like in the LEAF?
- xylem located on top of phloem
- only applies to dicotyledonous plants
what is the vascular bundle like in the STEM?
- xylem is located on the inside (in non-wooded plants)
- provides additional support to stem
- cambium layer contains meristems
what is the structure of a phloem vessel?
- thin layer of cytoplasm in sieve tube element
- dense cytoplasm of companion cell
- plasmodesmata links companion cell cytoplasm and sieve tube element
- large nucleus
- mitochondria
what is the structure of a xylem vessel?
- hollow tube (no cytoplasm)
- thick lignified walls
- non-lignified pit
- region where end cell wall has been lost
what do spirals of lignin running around the lumen of the xylem help with?
lignin reinforces xylem vessels so they don’t collapse under transpiration pull
