Plant Transport Flashcards
How does the structure of H20 help water movement in the xylem?
- The H2O molecule has a dipole over it (it is overall more negative)
- This causes cohesive forces of attraction between water molecules- allowing them to pull each other up
- Adhesive forces (between molecules and xylem wall) also help
What does the seed do with the water it has absorbed?
What are the metabolic events that take place?
1• Water activates the cotyledon cells so that gibberellin (a plant growth regulator) is synthesised
2• The gibberellin brings about the synthesis of the amylase
3• Starch is hydrolysed to maltose an is absorbed by the plant
4• The maltose can be further hydrolysed for glucose for respiration or polymerisation to cellulose for cell wall formation
5• ABA (absciscic acid) inhibits seed germination so that seeds enter dormancy period
How does water move from the roots to the leaves?
- Osmosis into root hair cell
- Apoplast pathway (through cells) and symplast pathways (through cytoplasm)
- Cohesion and adhesion move it up the xylem and to the leaf
What is the role of the xylem?
To keep the plant upright, held by hollow tubes of xylem tissues usually strengthened with lignin.
It also transports water and dissolved mineral salts.
How does water leave the leaf?
See diagram from 12th November 2014
