plant transport Flashcards
Why do multicellular plants need transport systems?
+ Metabolic demands, for example they require glucose and oxygen for photosynthesis and transport of several materials such as mineral ions and hormones
+ Large plants need transport systems to move substances from the roots to the tips
+ Surface area to volume ratio is small means they cannot reply on diffusion
What is a vascular system?
A vascular system is a series of transport vessels running through the stem, roots and leaves.
Made of the xylem and phloem arranged in vascular bundles.
What is the structure and function of the xylem?
+ Xylem are non-living tissue that transports water and mineral ions and for support up from the roots to the shoots
+ Xylem are made from long hollow structures made by cells fusing together
+ Have thick walled parenchyma that store food and tannin deposits
+ Have lignified walls that provide mechanical strength which can be in spirals
+ Has bordered pits where water leaves the xylem
What is the structure and function of the phloem?
+ A living tissue which transport foods in the form of solutes around from the photosynthesis products for respiration
+ They are made from sieve tube elements and are NOT lignified
+ Walls are perforated to form sieve plates and let phloem contents form through
+ Connected are companion cells linked by plasmodesmata which maintain nucleus and organelles
Why is water key in plants?
+ Turgor pressure provides a hydrostatic skeleton to support stems and leaves
+ Drives cell expansion
+ Loss of water via evaporation to keep plants cool
+ Mineral ions and products are transported in aqueous solution
+ Used in photosynthesis
How are root hair cells adapted for the movement of water into the root?
+ Microscopic size means they can penetrate through soil particles
+Large SA:V ratio
+ Thin surface layer through diffusion and osmosis
+ Maintains a water potential gradient due to the solutes in the cytoplasm of root hair cells
