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Roots 3 modification
lecture 16
| Question | Answer |
|---|---|
| functions of water include | carries nutrients from roots to plant, it is a solvent for chemical reaction, |
| water potential is used to predict.. | which way water wil move |
| units of water potential are | megapascals |
| osmosis | diffusion of water across a semi permeable membrane |
| turgid means | the cell is full of water |
| plasmolysis means | water has moved out of the cell |
| stomata control | the loss of water from a plant |
| there are two methods by which water enters roots | 1. active transport and 2 passive transport |
| active transport requires | energy in the form of ATP( adenosine tri phosphate) |
| passive transport is by | osmosis |
| water absorbed by plants enters by | root hairs |
| surface area for water absorption is further increased by | mycorrhizal fungi. Phosphorous is absorbed in this way |
| how many pathways are there for water movement | 3 |
| apoplast route | movement of water through the cell walls and the space between the cells |
| symplast route | movement of water through cytoplasm connected by plasmodesmata |
| transmembrane route | movement of water between cells and across the membranes of vacuoles |
| aquaporins | water channels in vacuoles and membranes |
| the driving force for tanspiration is | the gradient in the vapour pressure from 100% inside in the leaf to lower than 100 ourside |
| there are 3 methods of water movement in the xylem | transpiraton pull, cohesion adhesion forces and root pressure |
| transpiraton pull | force responsible for lifting a column of water. water lost for mesophill cells pressure is put on lower cells to replace water |
| cohesion adhesion theory | water molecules are cohesive and are held together by hydrogen bonds. water molecules are also adhesive and stick to the xylem vessels |
| root pressure | caused by active transport of nutrients into the root |