Life Processes in Living Organisms
- Transportation is a life process where substances synthesized or absorbed in one part of the body are carried to other parts of the body.
- Transportation in plants
- The transportation system in plants moves the energy stored in leaves to different parts. It also helps in moving raw materials absorbed from the roots to various organs of the plant.
- Xylem conducts water and minerals obtained from soil (via roots) to the rest of the plant.
- Transport of water occurs due to transpiration pull, root pressure and difference in pressure gradient.
- Phloem transports food materials from the leaves to different parts of the plant body.
- Transport of food (translocation) through phloem requires energy.
- Water movement
- Root pressure
- It is the positive pressure that develops in the roots of plants by active absorption of nutrients from soil.
- It pushes the water up to small heights.
- Root pressure is linked to the phenomenon of guttation.
- Guttation: It involves the loss of water in the form of liquid droplets through the vein endings of the leaves.
- Guttation occurs early in the morning and late in the evening when evaporation is low and root pressure is high.
- Transpiration Pull
- Water transport in tall trees occurs by transpiration pull.
- Transpiration pull is generated by transpiration. It is also called cohesion - tension - transpiration pull model of water transport.
- The ascent of xylem sap is dependent on three physical properties of water:
- Surface tension
It is a life process where substances synthesised or…
To view the complete topic, please