1. The vascular tissues in dicotyledonous & monocotyledonous plant.
- You shld be able to draw & label the cross-section (XS) of stem & root for both dicot. & monocot. plant.
- Able to differentiate between XS of dicot. & monocot.
- Diagram below show the XS & longitudinal section of dicot stem
2. Xylem:
- fn? to transport water & dissolved mineral salts/ions from the roots upto the stem. And to provide mechanical support in woody plant.
- Consists of xylem vessels, tracheids, parenchyma, fibres.
- Question: How does the xylem vessels adapt to function efficiently in water transportation?
3. Phloem:
- fn? transport organic food substances (eg: glucose, sucrose, amino acids) both upwards & downwards to various parts of a plant.
- consists of sieve tube cells, companion cells, parenchyma cells, fibres.
4. Movements of water from roots up to the leaves are assisted by:
- (i) Root pressure:
- Created by osmotic pressure of xylem sap which is created by dissoved minerals & sugars.
- It is an upward force that push water (& mineral salts) up to a certain height in plants. - (ii) Capillary action:
- combine the forces of cohesion & adhesion of water molecule.
- hold water column together in the capillary-sized xylem vessel. - (iii) Transpirational pull
- a pulling force/suction force that move water from leaves & stems & eventually from the xylem in the roots.
- pulling force is created due to transpiration/evaporation of water vapour from the mesophyll cells & the cohesive property of water.
5. What is transpiration?
- It is the loss of water in the form of water vapour (evaporation) from a plant to the atmosphere.
- Through the stomata of leaves (main channel), the cuticles & lenticels (woody stem).
- Roles of transpiration? create tranpiration pull, produce cooling effect, supply water for photosynthesis, support through cell turgidity.
6. What is translocation?
- is the two-way transport (upwards & downwards) of dissolved organic solute in the phloem, from the leaves to other parts of the plant.
7. Opening & closing of stomata.
8. Factors affecting the RoT.
- Light intensity
- Temperature
- Air movement
- Relative humidity
9. Potometer experiment to study RoT.
- assumption made? rate of water uptake by the root = rate of transpiration.
- Precautionary steps? make sure all connections are airtight. the leafy shoot must be cut & connected in a basin of water.
