STPM Biology - chapter 8: Revision essay question 2

2. a. What are the benefits of transpiration to the plant                                                    [3]

    b. Describe the pathways and explain the mechanisms by which water is absorbed from the
        soil and transported across the root and up to the leaves .                                       [12]


Answer:



2. a. 
- giving cooling effect
- help uptake of water and mineral ions by roots
- transport and distribution water and mineral ions through xylem
- distribution of water and mineral ions

2. b. 







- water is absorbed by root hairs following it concentration gradient
- by osmosis
- water move via cortex ,endodermis and pericycle
- by symplast,from cytoplasm into the cytoplasm of the next cell
- by apoplast pathway-water move along the cellulose cell wall
- by vacuolar pathway-water move into the sap vacuole and out into the vacuole of the next cell 1
- during transpiration/evaporation water loss from the mesophyll
- transpiration lower the water potential of leaf cells/mesophyll cells
- water is absorb by osmosis from the neighboring mesophyll cell
- down water potential gradient via apoplast ,symplast and vacuolar pathways in the leaves
- Creates transpiration pull along the xylem vessel of the stem/ creates a negative pressure in the  
   xylem vessel      
- water in the xylem is supported by continues water column
- due to adhesion and cohesion forces/capillarity

- root pressure