ZIMSEC O Level Combined Science Notes:Transpiration in plants
- Water enters plant roots at all hours of the day.
- Some trees absorb as much as 5 litres of water per minute.
- Over 95% of the water that enters a plant through the roots exits the plant via the leaves.
- Only a small amount of the water is used for processes inside the plant.
- The loss of water via the leaves is known as transpiration.
- Transpiration is the loss of water vapour from the leaves of a green plant.
- Water is lost from all plant surfaces but it is lost mainly through the leaves.
- As water is lost into the atmosphere it evaporates and helps to keep the plant cool.
- As water is lost through the plant stem and leaves more is brought in by the roots to replace the water that is lost.
- Water and ions from the soil enter the plant and move up through the plant.
- The water and ions are transported to all parts of the plant.
- It is used in processes like photosynthesis and growth.
- The rate of transpiration varies from plant to plant and from day to day.
- When a plant losses more water that it can absorb through the soil it wilts.
- This is because the plant cells lose water and become soft/limp.
- The cells lose their turgor (hardiness) and the leaves hang down.
- Sometimes the whole plant droops.
- If the loss continues to occur the plants will die.
To access more topics go to the Combined Science Notes page.